colon cancer

Contents

What is colon cancer

Colon cancer is cancer of the large intestine (colon), which is the final part of your digestive tract. The large intestine (colon) extends from the distal end of the ileum to the anus, a distance of approximately 1.5 m in adults (5 ft) long and 6.5 cm (2.5 in.) in diameter. Together, the rectum and anal canal make up the last part of the large intestine and are about 6-8 inches long. The anal canal ends at the anus (the opening of the large intestine to the outside of the body). Depending on where the cancer starts, colon cancer is sometimes called colon or rectal cancer or colorectal cancer. Most cases of colon cancer begin as small, noncancerous (benign) clumps of cells called adenomatous polyps. Over time some of these polyps can become colon cancers. Polyps may be small and produce few, if any, symptoms. For this reason, doctors recommend regular screening tests to help prevent colon cancer by identifying and removing polyps before they turn into cancer.

The chance of changing into a cancer depends on the kind of polyp. The 2 main types of polyps are:

  • Adenomatous polyps (adenomas): These polyps sometimes change into cancer. Because of this, adenomas are called a pre-cancerous condition.
  • Hyperplastic polyps and inflammatory polyps: These polyps are more common, but in general they are not pre-cancerous.

Other polyp characteristics that can increase the chances a polyp may contain cancer or increase someone’s risk of developing colorectal cancer besides the type include the size (larger than 1cm), the number found (more than two), and if dysplasia is seen in the polyp after it is removed.

Dysplasia, another pre-cancerous condition, is an area in a polyp or in the lining of the colon or rectum where the cells look abnormal (but not like true cancer cells).

If cancer forms in a polyp, it can eventually begin to grow into the wall of the colon or rectum.

The wall of the colon and rectum is made up of several layers. Colorectal cancer starts in the innermost layer (the mucosa) and can grow outward through some or all of the other layers. When cancer cells are in the wall, they can then grow into blood vessels or lymph vessels (tiny channels that carry away waste and fluid). From there, they can travel to nearby lymph nodes or to distant parts of the body.

The stage (extent of spread) of a colorectal cancer depends on how deeply it grows into the wall and if it has spread outside the colon or rectum.

It can take as many as 10 to 15 years for a polyp to develop into colorectal cancer. Regular screening can often prevent colorectal cancer by finding and removing polyps before they have the chance to turn into cancer. Screening can also often find colorectal cancer early, when it might be easier to treat.

Excluding skin cancers, colorectal cancer is the third most common cancer diagnosed in both men and women in the United States. The American Cancer Society’s estimates for the number of colorectal cancer cases in the United States for 2017 are:

  • 95,520 new cases of colon cancer
  • 39,910 new cases of rectal cancer

Overall, the lifetime risk of developing colorectal cancer is: about 1 in 21 (4.7%) for men and 1 in 23 (4.4%) for women. This risk is slightly lower in women than in men. A number of other factors (described in Colorectal Cancer Risk Factors) can also affect your risk for developing colorectal cancer.

Colorectal cancer is the second leading cause of cancer death when numbers for both men and women are combined. The death rate (the number of deaths per 100,000 people per year) of colorectal cancer has been dropping for several decades. It is expected to cause about 50,260 deaths during 2017. One reason for this is that colorectal polyps are now more often found by screening and removed before they can develop into cancers.

When colorectal cancer is found at an early stage before it has spread, the 5-year relative survival rate is about 90%. But only about 4 out of 10 colorectal cancers are found at this early stage. When cancer has spread outside the colon or rectum, survival rates are lower.

Unfortunately, only a little more than half of people who should get tested for colorectal cancer get the tests that they should. This may be due to things like lack of public and health care provider awareness of screening options, costs, and health insurance coverage issues.

Figure 1. Large intestine (colon)

large intestine

What is a polyp in the colon?

A polyp is a projection (growth) of tissue from the inner lining of the colon into the lumen (hollow center) of the colon. Different types of polyps look different under the microscope. Polyps are benign (non-cancerous) growths, but cancer can start in some types of polyps. These polyps can be thought of as pre-cancers, which is why it is important to have them removed.

Polyps that tend to grow as slightly flattened, broad-based polyps are referred to as sessile.

Serrated polyps (serrated adenomas) have a saw-tooth appearance under the microscope. There are 2 types, which look a little different under the microscope:

  • Sessile serrated adenomas (also called sessile serrated polyps)
  • Traditional serrated adenomas

Both types need to be removed from your colon.

What is an adenoma (adenomatous polyp)?

An adenoma is a polyp made up of tissue that looks much like the normal lining of your colon, although it is different in several important ways when it is looked at under the microscope. In some cases, a cancer can start in the adenoma.

What are tubular adenomas, tubulovillous adenomas, and villous adenomas?

Adenomas can have several different growth patterns that can be seen under the microscope by the pathologist. There are 2 major growth patterns: tubular and villous. Many adenomas have a mixture of both growth patterns, and are called tubulovillous adenomas. Most adenomas that are small (less than ½ inch) have a tubular growth pattern. Larger adenomas may have a villous growth pattern. Larger adenomas more often have cancers developing in them. Adenomas with a villous growth pattern are also more likely to have cancers develop in them.

The most important thing is that your polyp has been completely removed and does not show cancer. The growth pattern is only important because it helps determine when you will need your next colonoscopy to make sure you don’t develop colon cancer in the future.

What does it mean if I have an adenoma (adenomatous polyp), such as a sessile serrated adenoma or traditional serrated adenoma?

These types of polyps are not cancer, but they are pre-cancerous (meaning that they can turn into cancers). Someone who has had one of these types of polyps has an increased risk of later developing cancer of the colon. Most patients with these polyps, however, never develop colon cancer.

What if my report mentions dysplasia?

Dysplasia is a term that describes how much your polyp looks like cancer under the microscope:

  • Polyps that are only mildly abnormal (don’t look much like cancer) are said to have low-grade (mild or moderate) dysplasia.
  • Polyps that are more abnormal and look more like cancer are said to have high-grade (severe) dysplasia.

The most important thing is that your polyp has been completely removed and does not show cancer. If high-grade dysplasia is found in your polyp, it might mean you need to have a repeat (follow-up) colonoscopy sooner than if high-grade dysplasia wasn’t found, but otherwise you do not need to worry about dysplasia in your polyp.

How does having an adenoma affect my future follow-up care?

Since you had an adenoma, you will need to have another colonoscopy to make sure that you don’t develop any more adenomas. When your next colonoscopy should be scheduled depends on a number of things, like how many adenomas were found, if any were villous, and if any had high-grade dysplasia. The timing of your next colonoscopy should be discussed with your treating doctor, as he or she knows the details of your specific case.

What if my adenoma was not completely removed?

If your adenoma was biopsied but not completely removed, you will need to talk to your doctor about what other treatment you’ll need. Most of the time, adenomas are removed during a colonoscopy. Sometimes, though, the adenoma may be too large to remove during colonoscopy. In such cases you may need surgery to have the adenoma removed.

What if my report also mentions hyperplastic polyps?

Hyperplastic polyps are typically benign (they aren’t pre-cancers or cancers) and are not a cause for concern.

Colon cancer causes

In most cases, it’s not clear what causes colon cancer. Doctors know that colon cancer occurs when healthy cells in the colon develop errors in their genetic blueprint, the DNA.

Healthy cells grow and divide in an orderly way to keep your body functioning normally. But when a cell’s DNA is damaged and becomes cancerous, cells continue to divide — even when new cells aren’t needed. As the cells accumulate, they form a tumor.

With time, the cancer cells can grow to invade and destroy normal tissue nearby. And cancerous cells can travel to other parts of the body to form deposits there (metastasis).

Inherited gene mutations that increase the risk of colon cancer

Inherited gene mutations that increase the risk of colon cancer can be passed through families, but these inherited genes are linked to only a small percentage of colon cancers. Inherited gene mutations don’t make cancer inevitable, but they can increase an individual’s risk of cancer significantly.

The most common forms of inherited colon cancer syndromes are:

  • Hereditary nonpolyposis colorectal cancer (HNPCC). Hereditary nonpolyposis colorectal cancer, also called Lynch syndrome, increases the risk of colon cancer and other cancers. People with hereditary nonpolyposis colorectal cancer tend to develop colon cancer before age 50.
  • Familial adenomatous polyposis (FAP). Familial adenomatous polyposis is a rare disorder that causes you to develop thousands of polyps in the lining of your colon and rectum. People with untreated familial adenomatous polyposis have a greatly increased risk of developing colon cancer before age 40.

Familial adenomatous polyposis, hereditary nonpolyposis colorectal cancer and other, rarer inherited colon cancer syndromes can be detected through genetic testing. If you’re concerned about your family’s history of colon cancer, talk to your doctor about whether your family history suggests you have a risk of these conditions.

Association between diet and increased colon cancer risk

Studies of large groups of people have shown an association between a typical Western diet and an increased risk of colon cancer. A typical Western diet is high in fat and low in fiber.

When people move from areas where the typical diet is low in fat and high in fiber to areas where the typical Western diet is most common, the risk of colon cancer in these people increases significantly. It’s not clear why this occurs, but researchers are studying whether a high-fat, low-fiber diet affects the microbes that live in the colon or causes underlying inflammation that may contribute to cancer risk. This is an area of active investigation and research is ongoing.

Risk factors for colon cancer

Anything that increases your chance of getting a disease is called a risk factor. Having a risk factor does not mean that you will get cancer; not having risk factors doesn’t mean that you will not get cancer. Talk to your doctor if you think you may be at risk for colorectal cancer.

Factors that may increase your risk of colon cancer include:

  • Older age. The great majority of people diagnosed with colon cancer are older than 50. Colon cancer can occur in younger people, but it occurs much less frequently.
  • African-American race. African-Americans have a greater risk of colon cancer than do people of other races.
  • Having a personal history of cancer of the colon, rectum, or ovary.
  • Having a personal history of high-risk adenomas (colorectal polyps that are 1 centimeter or larger in size or that have cells that look abnormal under a microscope).
  • Inflammatory intestinal conditions. Chronic inflammatory diseases of the colon, such as ulcerative colitis and Crohn’s disease, can increase your risk of colon cancer.
  • Inherited syndromes that increase colon cancer risk. Genetic syndromes passed through generations of your family can increase your risk of colon cancer. These syndromes include familial adenomatous polyposis (FAP) and hereditary nonpolyposis colorectal cancer, which is also known as Lynch syndrome.
  • Family history of colon cancer. You’re more likely to develop colon cancer if you have a parent, sibling or child with the disease. If more than one family member has colon cancer or rectal cancer, your risk is even greater.
  • Low-fiber, high-fat diet. Colon cancer and rectal cancer may be associated with a diet low in fiber and high in fat and calories. Research in this area has had mixed results. Some studies have found an increased risk of colon cancer in people who eat diets high in red meat and processed meat.
  • A sedentary lifestyle. If you’re inactive, you’re more likely to develop colon cancer. Getting regular physical activity may reduce your risk of colon cancer.
  • Diabetes. People with diabetes and insulin resistance have an increased risk of colon cancer.
  • Obesity. People who are obese have an increased risk of colon cancer and an increased risk of dying of colon cancer when compared with people considered normal weight.
  • Smoking. People who smoke may have an increased risk of colon cancer.
  • Alcohol. Having three or more alcoholic drinks per day increases your risk of colon cancer.
  • Radiation therapy for cancer. Radiation therapy directed at the abdomen to treat previous cancers increases the risk of colon and rectal cancer.

Prevention of colon cancer

Get screened for colon cancer

People with an average risk of colon cancer can consider screening beginning at age 50. But people with an increased risk, such as those with a family history of colon cancer, should consider screening sooner.

Several screening options exist — each with its own benefits and drawbacks. Talk about your options with your doctor, and together you can decide which tests are appropriate for you.

Make lifestyle changes to reduce your risk

You can take steps to reduce your risk of colon cancer by making changes in your everyday life. Take steps to:

  • Eat a variety of fruits, vegetables and whole grains. Fruits, vegetables and whole grains contain vitamins, minerals, fiber and antioxidants, which may play a role in cancer prevention. Choose a variety of fruits and vegetables so that you get an array of vitamins and nutrients.
  • Drink alcohol in moderation, if at all. If you choose to drink alcohol, limit the amount of alcohol you drink to no more than one drink a day for women and two for men.
  • Stop smoking. Talk to your doctor about ways to quit that may work for you.
  • Exercise most days of the week. Try to get at least 30 minutes of exercise on most days. If you’ve been inactive, start slowly and build up gradually to 30 minutes. Also, talk to your doctor before starting any exercise program.
  • Maintain a healthy weight. If you are at a healthy weight, work to maintain your weight by combining a healthy diet with daily exercise. If you need to lose weight, ask your doctor about healthy ways to achieve your goal. Aim to lose weight slowly by increasing the amount of exercise you get and reducing the number of calories you eat.

Colon cancer prevention for people with a high risk

Some medications have been found to reduce the risk of precancerous polyps or colon cancer. However, not enough evidence exists to recommend these medications to people who have an average risk of colon cancer. These options are generally reserved for people with a high risk of colon cancer.

For instance, some evidence links a reduced risk of polyps and colon cancer to regular use of aspirin or aspirin-like drugs. But it’s not clear what dose and what length of time would be needed to reduce the risk of colon cancer. Taking aspirin daily has some risks, including gastrointestinal bleeding and ulcers, so doctors typically don’t recommend this as a prevention strategy unless you have an increased risk of colon cancer.

Screening Tests for Colorectal Cancer

Doctors recommend certain screening tests for healthy people with no signs or symptoms in order to look for early colon cancer. Finding colon cancer at its earliest stage provides the greatest chance for a cure. Screening has been shown to reduce your risk of dying of colon cancer.

People with an average risk of colon cancer can consider screening beginning at age 50. But people with an increased risk, such as those with a family history of colon cancer, should consider screening sooner. African-Americans and American Indians may consider beginning colon cancer screening at age 45.

Several screening options exist — each with its own benefits and drawbacks. Talk about your options with your doctor, and together you can decide which tests are appropriate for you. If a colonoscopy is used for screening, polyps can be removed during the procedure before they turn into cancer.

The American Cancer Society believes that preventing colorectal cancer (and not just finding it early) should be a major reason for getting tested. Having polyps found and removed keeps some people from getting colorectal cancer. You are encouraged to have tests that have the best chance of finding both polyps and cancer if these tests are available to you and you are willing to have them. But the most important thing is to get tested, no matter which test you choose.

Starting at age 50, men and women at average risk for developing colorectal cancer should use one of the screening tests below:

Screening is the process of looking for cancer in people who have no symptoms. Several tests can be used to screen for colorectal cancers. These tests can be divided into:

Tests that find polyps and cancer

  • Colonoscopy every 10 years
  • CT colonography (virtual colonoscopy) every 5 years*
  • Flexible sigmoidoscopy every 5 years*
  • Double-contrast barium enema every 5 years*

Tests that mainly find cancer

  • Fecal immunochemical test (FIT) every year*,**
  • Guaiac-based fecal occult blood test (gFOBT) every year*,**
  • Stool DNA test every 3 years*

*Colonoscopy should be done if test results are positive.
** Highly sensitive versions of these tests should be used with the take-home multiple sample method. A gFOBT or FIT done during a digital rectal exam in the doctor’s office is not enough for screening.

Tests that can find both colorectal polyps and cancer are encouraged if they are available and you are willing to have them. But the most important thing is to get tested, no matter which test you choose.

These tests, as well as others, can also be used when people have symptoms of colorectal cancer and other digestive diseases such as inflammatory bowel disease.

People at increased or high risk

If you are at an increased or high risk of colorectal cancer, you might need to start colorectal cancer screening before age 50 and/or be screened more often. The following conditions make your risk higher than average:

  • A personal history of colorectal cancer or adenomatous polyps
  • A personal history of inflammatory bowel disease (ulcerative colitis or Crohn’s disease)
  • A strong family history of colorectal cancer or polyps (see Colorectal Cancer Risk Factors)
  • A known family history of a hereditary colorectal cancer syndrome such as familial adenomatous polyposis (FAP) or Lynch syndrome (hereditary non-polyposis colon cancer or HNPCC)

The table below suggests screening guidelines for people with increased or high risk of colorectal cancer based on specific risk factors. Some people may have more than one risk factor. Refer to the table below and discuss these recommendations with your health care provider. Your provider can suggest the best screening option for you, as well as any changes in the schedule based on your individual risk.

Table 1. American Cancer Society Guidelines on Screening and Surveillance for the Early Detection of Colorectal Adenomas and Cancer in People at Increased Risk or High Risk

INCREASED RISK – People who have a history of polyps on prior colonoscopy
Risk categoryWhen to testRecommended test(s)Comment
People with small rectal hyperplastic polypsSame age as those at average riskColonoscopy, or other screening options at same intervals as for those at average riskThose with hyperplastic polyposis syndrome are at increased risk for adenomatous polyps and cancer and should have more intensive follow-up.
People with 1 or 2 small (no more than 1 cm) tubular adenomas with low-grade dysplasia5 to 10 years after the polyps are removedColonoscopyTime between tests should be based on other factors such as prior colonoscopy findings, family history, and patient and doctor preferences.
People with 3 to 10 adenomas, or a large (at least 1 cm) adenoma, or any adenomas with high-grade dysplasia or villous features3 years after the polyps are removedColonoscopyAdenomas must have been completely removed. If colonoscopy is normal or shows only 1 or 2 small tubular adenomas with low-grade dysplasia, future colonoscopies can be done every 5 years.
People with more than 10 adenomas on a single examWithin 3 years after the polyps are removedColonoscopyDoctor should consider possible genetic syndrome (such as FAP or Lynch syndrome).
People with sessile adenomas that are removed in pieces2 to 6 months after adenoma removalColonoscopyIf entire adenoma has been removed, further testing should be based on doctor’s judgment.
INCREASED RISK – People who have had colorectal cancer
Risk categoryWhen to testRecommended test(s)Comment
People diagnosed with colon or rectal cancerAt time of colorectal surgery, or can be 3 to 6 months later if person doesn’t have cancer spread that can’t be removedColonoscopy to look at the entire colon and remove all polypsIf the tumor presses on the colon/rectum and prevents colonoscopy, CT colonoscopy (with IV contrast) or DCBE may be done to look at the rest of the colon.
People who have had colon or rectal cancer removed by surgeryWithin 1 year after cancer resection (or 1 year after colonoscopy to make sure the rest of the colon/rectum was clear)ColonoscopyIf normal, repeat in 3 years. If normal then, repeat test every 5 years. Time between tests may be shorter if polyps are found or there’s reason to suspect Lynch syndrome. After low anterior resection for rectal cancer, exams of the rectum may be done every 3 to 6 months for the first 2 to 3 years to look for signs of recurrence.
INCREASED RISK – People with a family history
Risk categoryAge to start testingRecommended test(s)Comment
Colorectal cancer or adenomatous polyps in any first-degree relative before age 60, or in 2 or more first-degree relatives at any age (if not a hereditary syndrome).Age 40, or 10 years before the youngest case in the immediate family, whichever is earlierColonoscopyEvery 5 years.
Colorectal cancer or adenomatous polyps in any first-degree relative aged 60 or older, or in at least 2 second-degree relatives at any ageAge 40Same test options as for those at average risk.Same test intervals as for those at average risk.
HIGH RISK
Risk categoryAge to start testingRecommended test(s)Comment
Familial adenomatous polyposis (FAP) diagnosed by genetic testing, or suspected FAP without genetic testingAge 10 to 12Yearly flexible sigmoidoscopy to look for signs of FAP; counseling to consider genetic testing if it hasn’t been doneIf genetic test is positive, removal of colon (colectomy) should be considered.
Lynch syndrome (hereditary non-polyposis colon
cancer or HNPCC), or at increased risk of Lynch syndrome based on family history without genetic testing
Age 20 to 25 years, or 10 years before the youngest case in the immediate familyColonoscopy every 1 to 2 years; counseling to consider genetic testing if it hasn’t been doneGenetic testing should be offered to first-degree relatives of people found to have Lynch syndrome mutations by genetic tests. It should also be offered if 1 of the first 3 of the modified Bethesda criteria is met.*
Inflammatory bowel disease:

-Chronic ulcerative colitis

-Crohn’s disease

Cancer risk begins to be significant 8 years after the onset of pancolitis (involvement of entire large intestine), or 12-15 years after the onset of left-sided colitisColonoscopy every 1 to 2 years with biopsies for dysplasiaThese people are best referred to a center with experience in the surveillance and management of inflammatory bowel disease.

Tests that can find both colorectal polyps and cancer

Flexible sigmoidoscopy

During this test, the doctor looks at part of the colon and rectum with a sigmoidoscope (a flexible, lighted tube about the thickness of a finger with a small video camera on the end). It’s put in through the anus and into the rectum and moved into the lower part of the colon. Images from the scope are seen on a video screen.

Using the sigmoidoscope, your doctor can look at the inside of the rectum and part of the colon to detect (and possibly remove) any abnormality. The sigmoidoscope is only 60 centimeters (about 2 feet) long, so the doctor is able to see the entire rectum but less than half of the colon with this procedure.

This test is not widely used as a screening test for colorectal cancer in the United States.

Before the test: Be sure your doctor knows about any medicines you take. You might need to change how you take them before the test. Your insides must be empty and clean so your doctor can see the lining of the sigmoid colon and rectum. You will get specific instructions to follow to clean them out. You may be asked to follow a special diet (such as drinking only clear liquids) or to use enemas or strong laxatives the day before the test to clean out your colon.

During the test: A sigmoidoscopy usually takes about 10 to 20 minutes. Most people don’t need to be sedated for this test, but this might be an option you can discuss with your doctor. Sedation may make the test less uncomfortable, but you’ll need some time to recover from it and you’ll need someone with you to take you home after the test.

You’ll probably be asked to lie on a table on your left side with your knees pulled up near your chest. Before the test, your doctor may put a gloved, lubricated finger into your rectum to examine it. For the test itself, the sigmoidoscope is first lubricated to make it easier to insert into the rectum. The scope may feel cold as it’s put in. Air will be pumped into the colon through the sigmoidoscope so the doctor can see the walls of the colon better.

If you are not sedated during the procedure, you might feel pressure and slight cramping in your lower belly. To ease discomfort and the urge to have a bowel movement, it helps to breathe deeply and slowly through your mouth. You’ll feel better after the test once the air leaves your colon.

If a polyp is found during the test, the doctor may remove it with a small instrument passed through the scope. The polyp will be looked at in the lab. If a pre-cancerous polyp (an adenoma) or colorectal cancer is found, you’ll need to have a colonoscopy (see below) later to look for polyps or cancer in the rest of the colon.

Possible complications and side effects: This test may be uncomfortable because of the air put into the colon, but it should not be painful. Be sure to let your doctor know if you feel pain during the procedure. You might see a small amount of blood in your first bowel movement after the test. More serious bleeding and puncture of the colon are possible complications, but they are very uncommon.

Figure 2. Sigmoidoscopy. A thin, lighted tube is inserted through the anus and rectum and into the lower part of the colon to look for abnormal areas

Sigmoidoscopy

Colonoscopy

For this test, the doctor looks at the entire length of the colon and rectum with a colonoscope, a thin, flexible, lighted tube with a small video camera on the end. It’s basically a longer version of a sigmoidoscope. It’s put in through the anus and into the rectum and colon. Special instruments can be passed through the colonoscope to biopsy (sample) or remove any suspicious-looking areas such as polyps, if needed.

Before the test: Be sure your doctor knows about any medicines you are taking. You might need to change how you take them before the test. The colon and rectum must be empty and clean so your doctor can see the lining of the entire colon and rectum during the test. This process of cleaning out the colon and rectum is sometimes unpleasant and can keep people from getting this important screening test done. However, newer kits are available to clean out the bowel and may be better tolerated than previous ones. Your doctor can discuss the options with you.

Your doctor will give you specific instructions. It’s important to read them carefully a few days ahead of time, since you may need to follow a special diet for at least a day before the test and to shop for supplies and laxatives. If you’re not sure about any of the instructions, call the doctor’s office and go over them with the nurse.

You will probably also be told not to eat or drink anything after midnight the night before your test. If you normally take prescription medicines in the mornings, talk with your doctor or nurse about how to manage them for that day.

Because a sedative is used during the test, you will need to arrange for someone you know to take you home after the test. You might need someone to help you get into your home if you are sleepy or dizzy, so many centers that do colonoscopies will not discharge people to go home in a cab or a ridesharing service. If transportation might be a problem, talk with your health care provider about the policy at your hospital or surgery center for using one of these services. There may be other resources available for getting home, depending on the situation.

During the test: The test itself usually takes about 30 minutes, but it may take longer if a polyp is found and removed. Before it starts, you’ll be given a sedating medicine (into a vein) to make you feel relaxed and sleepy during the procedure. For most people, this medicine makes them unaware of what’s going on and unable to remember the procedure afterward. You’ll wake up after the test is over, but might not be fully awake until later in the day.

During the test, you’ll be asked to lie on your side with your knees pulled up. A drape will cover you. Your blood pressure, heart rate, and breathing rate will be monitored during and after the test.

Your doctor might insert a gloved finger into the rectum to examine it before putting in the colonoscope. The colonoscope is lubricated so it can be inserted easily into the rectum. Once in the rectum, the colonoscope is passed all the way to the beginning of the colon, called the cecum.

If you’re awake, you may feel an urge to have a bowel movement when the colonoscope is inserted or pushed further up the colon. The doctor also puts air into the colon through the colonoscope to make it easier to see the lining of the colon and use the instruments to perform the test. To ease any discomfort, it may help to breathe deeply and slowly through your mouth.

The doctor will look at the inner walls of the colon as he or she slowly removes the colonoscope. If a small polyp is found, it may be removed and then sent to a lab to be checked if it has any areas that have changed into cancer. This is because some small polyps may become cancer over time.

If your doctor sees a larger polyp or tumor or anything else abnormal, a biopsy may be done. A small piece of tissue is taken out through the colonoscope. The tissue is checked in the lab to see if it’s cancer, a benign (non-cancerous) growth, or inflammation.

Possible side effects and complications: The bowel preparation before the test is unpleasant. The test itself might be uncomfortable, but the sedative usually helps with this, and most people feel normal once the effects of the sedative wear off. Because air is pumped into the colon during the test, people sometimes feel bloated, have gas pains, or have cramping for a while after the test until the air passes out.

Some people may have low blood pressure or changes in heart rhythm from the sedation during the test, but these are rarely serious.

If a polyp is removed or a biopsy is done during the colonoscopy, you might notice some blood in your stool for a day or 2 after the test. Serious bleeding is uncommon, but in rare cases, bleeding might need to be treated or can even be life-threatening.

Colonoscopy is a safe procedure, but in rare cases the colonoscope can puncture the wall of the colon or rectum. This is called a perforation. Symptoms can include severe abdominal (belly) pain, nausea, and vomiting. This can be a major (or even life-threatening) complication, because it can lead to a serious abdominal (belly) infection. The hole may need to be repaired with surgery. Ask your doctor about the risk of this complication.

Figure 3. Colonoscopy

colonoscopy

Double-contrast barium enema (DCBE)

This test is also called an air-contrast barium enema or a barium enema with air contrast. It may also be called a lower GI series. It’s basically a type of x-ray test. Barium sulfate, which is a chalky liquid, and air are put into the colon and rectum through the anus to outline the inner lining. This can show abnormal areas on x-rays. If suspicious areas are seen on this test, a colonoscopy will need to be done to explore them further.

This test is not widely used as a screening test for colorectal cancer in the United States.

Before the test: It’s very important that the colon and rectum are empty and clean so they can be seen during the test. You’ll be given specific instructions on how to prepare for the test. For example, you may be asked to clean your bowel the night before with laxatives and/or take enemas the morning of the exam. You’ll probably be asked to follow a clear liquid diet for at least a day before the test. You may also be told to avoid eating or drinking dairy products the day before the test, and to not eat or drink anything after midnight the night before the test.

During the test: The test takes about 30 to 45 minutes, and sedation isn’t needed. You lie on a table on your side in an x-ray room. A small, flexible tube is put into your rectum, and barium sulfate is pumped in to partially fill and open up the colon and rectum. You are then turned on the x-ray table so the barium moves throughout the colon and rectum. Then air is pumped into the colon and rectum through the same tube to expand them. This might cause some cramping and discomfort, and you may feel the urge to have a bowel movement.

X-ray pictures of the lining of your colon and rectum are then taken to look for polyps or cancers. You may be asked to change positions to help move the barium and so that different views of the colon and rectum can be seen on the x-rays.

If polyps or other suspicious areas are seen on this test, you’ll probably need a colonoscopy to remove them or to study them fully.

Possible side effects and complications: You may have bloating or cramping after the test, and will probably feel the need to empty your bowels soon after the test is done. The barium can cause constipation for a few days, and your stool may look grey or white until all the barium is out. There’s a very small risk that inflating the colon with air could injure or puncture it, but this risk is thought to be much less than with colonoscopy. Like other x-ray tests, this test also exposes you to a small amount of radiation.

Figure 4. Barium enema

barium enema
CT colonography (virtual colonoscopy)

This test is an advanced type of computed tomography (CT or CAT) scan of the colon and rectum. A CT scan uses x-rays, but instead of taking one picture, like a regular x-ray, a CT scanner takes many pictures as it rotates around you while you lie on a table. A computer then combines these pictures into detailed images of the part of your body being studied.

For CT colonography, special computer programs create both 2-dimensional x-ray pictures and a 3-dimensional view of the inside of the colon and rectum, which lets the doctor look for polyps or cancer.

This test may be especially useful for some people who can’t have or don’t want to have more invasive tests such as colonoscopy. It can be done fairly quickly, and sedation isn’t needed. But even though this test is not invasive like a colonoscopy, the same type of bowel prep is needed. Also, a small, flexible tube is put in the rectum to fill the colon with air. Another possible drawback is that if polyps or other suspicious areas are seen on this test, a colonoscopy will still probably be needed to remove them or to explore them fully.

Before the test: It’s important that the colon and rectum are emptied before this test to get the best images. You’ll probably be told to follow a clear liquid diet for at least a day before the test. There are a number of ways to clean out the colon before the test. Often, the evening before the procedure, you drink large amounts of a liquid laxative solution. This often results in spending a lot of time in the bathroom. The morning of the test, sometimes more laxatives or enemas may be needed to make sure the bowels are empty. Newer kits are available to clean out the bowel and may be better tolerated than previous ones. Your doctor can discuss the options with you.

During the test: This test is done in a special room with a CT scanner. It takes about 10 minutes. You may be asked to drink a contrast solution before the test to help “tag” any stool left in the colon or rectum, which helps the doctor when looking at the test images. You’ll be asked to lie on a narrow table that’s part of the CT scanner, and will have a small, flexible tube put into your rectum. Air is pumped through the tube into the colon and rectum to expand them to provide better images. The table then slides into the CT scanner, and you’ll be asked to hold your breath for about 15 seconds while the scan is done. You’ll likely have 2 scans: one while you’re lying on your back and one while you’re on your stomach or side.

Possible side effects and complications: There are usually few side effects after this test. You may feel bloated or have cramps because of the air in the colon and rectum, but this should go away once the air passes from the body. There’s a very small risk that inflating the colon with air could injure or puncture it, but this risk is thought to be much less than with colonoscopy. Like other types of CT scans, this test also exposes you to a small amount of radiation

Tests that mainly find colorectal cancer

These tests look at the stool (feces) for signs of cancer. Most people find these tests easier to have than tests like colonoscopy, and they can often be done at home. But these tests aren’t as good at finding polyps such as tests like colonoscopy. And if the result from one of these stool tests is positive (abnormal), you’ll probably still need a colonoscopy to see if you have cancer.

Guaiac-based fecal occult blood test (gFOBT)

One way to test for colorectal cancer is to look for occult (hidden) blood in stool. The idea behind this test is that blood vessels in larger colorectal polyps or cancers are often fragile and easily damaged by the passage of stool. The damaged vessels usually bleed into the colon, but only rarely is there enough bleeding for blood to be seen in the stool.

The guaiac-based fecal occult blood test (gFOBT) detects blood in the stool through a chemical reaction. This test can’t tell if the blood is from the colon or from other parts of the digestive tract (such as the stomach). If this test is positive, a colonoscopy will be needed to find the reason for the bleeding. Although blood in the stool can be from cancers or polyps, it can also have other causes, such as ulcers, hemorrhoids, diverticulosis (tiny pouches that form at weak spots in the colon wall), or inflammatory bowel disease (colitis).

Over time, this test has improved so that it’s now more likely to find colorectal cancer. The American Cancer Society recommends the more modern, highly sensitive versions of this test for screening.

This test must be done every year, unlike some other tests (like colonoscopy).

This test is done with a kit that you can use in the privacy of your own home that allows you to check more than one stool sample. A FOBT done during a digital rectal exam in the doctor’s office (which only checks one stool sample) is not enough for proper screening.

People having this test will get a kit with instructions from their doctor’s office or clinic. The kit will explain how to take stool samples at home (usually samples from 3 straight bowel movements are smeared onto small squares of paper). The kit is then returned to the doctor’s office or medical lab (usually within 2 weeks) for testing.

Before the test: Some foods or drugs can affect the results, so you may be instructed to avoid the following before this test:

  • Non-steroidal anti-inflammatory drugs (NSAIDs), such as ibuprofen (Advil), naproxen (Aleve), or aspirin (more than 1 adult aspirin per day), for 7 days before testing. (They can cause bleeding, which can lead to a false-positive result.) Note: People should try to avoid taking NSAIDs for minor aches. But if you take these medicines daily for heart problems or other conditions, don’t stop them for this test without talking to your doctor first.
  • Vitamin C in excess of 250 mg daily from either supplements or citrus fruits and juices for 3 days before testing. (This can affect the chemicals in the test and make the result negative, even if blood is present.)
  • Red meats (beef, lamb, or liver) for 3 days before testing. (Components of blood in the meat may cause a positive test result.)

Some people who are given the test never do it or don’t return it because they worry that something they ate may affect the test. Even if you are concerned that something you ate may alter the test, the most important thing is to get the test done.

Collecting the samples: Have all of your supplies ready and in one place. Supplies typically include a test kit, test cards, either a brush or wooden applicator, and a mailing envelope. The kit will give you detailed instructions on how to collect the stool samples. Be sure to follow the instructions that come with your kit, as different kits might have different instructions. If you have any questions about how to use your kit, contact your doctor’s office or clinic. Once you have collected the samples, return them as instructed in the kit.

If this test finds blood, you will need a colonoscopy to look for the source. It’s not enough to simply repeat the gFOBT or follow up with other types of tests.

Fecal immunochemical test (FIT)

The fecal immunochemical test (FIT) is also called an immunochemical fecal occult blood test (iFOBT). It tests for occult (hidden) blood in the stool in a different way than a guaiac-based FOBT. This test reacts to part of the human hemoglobin protein, which is found in red blood cells.

The FIT is done much like the gFOBT, in that small amounts of stool are collected on cards (or in tubes). Some people may find this test easier because there are no drug or dietary restrictions (vitamins and foods do not affect the FIT), and collecting the samples may be easier. This test is also less likely to react to bleeding from other parts of digestive tract, such as the stomach.

Like the gFOBT, the FIT may not detect a tumor that’s not bleeding, so multiple stool samples should be tested. This test must also be done every year. And if the results are positive for hidden blood, a colonoscopy will be needed to investigate further.

Collecting the samples: Have all of your supplies ready and in one place. Supplies typically include a test kit, test cards or tubes, long brushes or other collecting devices, waste bags, and a mailing envelope. The kit will give you detailed instructions on how to collect the samples. Be sure to follow the instructions that come with your kit, as different kits might have different instructions. If you have any questions about how to use your kit, contact your doctor’s office or clinic. Once you have collected the samples, return them as instructed in the kit.

Stool DNA test

A stool DNA test looks for certain abnormal sections of DNA from cancer or polyp cells. Colorectal cancer cells often have DNA mutations (changes) in certain genes. Cells from colorectal cancers or polyps with these mutations often get into the stool, where tests may be able to detect them. Cologuard®, the test currently available, also tests for blood in the stool.

Collecting the samples: You’ll get a kit in the mail to use to collect your entire stool sample. The kit will have a sample container, a bracket for holding the container in the toilet, a bottle of liquid preservative, a tube, labels, and a shipping box. The kit has detailed instructions on how to collect the sample. Be sure to follow the instructions that come with your kit. If you have any questions about how to use your kit, contact your doctor’s office or clinic. Once you have collected the sample, return it as instructed in the kit.

This test should be done every 3 years. If the test is positive (if it finds DNA changes or blood), a colonoscopy will be needed.

Table 2. The pros and cons of colorectal cancer screening tests

TestProsCons
Flexible sigmoidoscopyFairly quick and safe

Usually doesn’t require full bowel prep

Sedation usually not used

Does not require a specialist

Done every 5 years

Looks at only about a third of the colon

Can miss small polyps

Can’t remove all polyps

May be some discomfort

Very small risk of bleeding, infection, or bowel tear

Colonoscopy will be needed if abnormal

ColonoscopyCan usually look at the entire colon

Can biopsy and remove polyps

Done every 10 years

Can help find some other diseases

Can miss small polyps

Full bowel prep needed

Costs more on a one-time basis than other forms of testing

Sedation is usually needed

You will need someone to drive you home

You may miss a day of work

Small risk of bleeding, bowel tears, or infection

Double-contrast barium enema (DCBE)Can usually see the entire colon

Relatively safe

Done every 5 years

No sedation needed

Can miss small polyps

Full bowel prep needed

Some false positive test results

Can’t remove polyps during testing

Colonoscopy will be needed if abnormal

CT colonography (virtual colonoscopy)Fairly quick and safe

Can usually see the entire colon

Done every 5 years

No sedation needed

Can miss small polyps

Full bowel prep needed

Some false positive test results

Can’t remove polyps during testing

Colonoscopy will be needed if abnormal

Still fairly new – may be insurance issues

Guaiac-based fecal occult blood test (gFOBT)No direct risk to the colon

No bowel prep

Sampling done at home

Inexpensive

Can miss many polyps and some cancers

Can produce false-positive test results

Pre-test diet changes are needed

Needs to be done every year

Colonoscopy will be needed if abnormal

Fecal immunochemical test (FIT)No direct risk to the colon

No bowel prep

No pre-test diet changes

Sampling done at home

Fairly inexpensive

Can miss many polyps and some cancers

Can produce false-positive test results

Needs to be done every year

Colonoscopy will be needed if abnormal

Stool DNA testNo direct risk to the colon

No bowel prep

No pre-test diet changes

Sampling done at home

Can miss many polyps and some cancers

Can produce false-positive test results

Should be done every 3 years

Colonoscopy will be needed if abnormal

Still fairly new – may be insurance issues

[Source 1)]

Colon cancer signs and symptoms

Many of the symptoms of colon cancer can also be caused by something that isn’t cancer, such as infection, hemorrhoids, irritable bowel syndrome, or inflammatory bowel disease.

Signs and symptoms of colon cancer include:

  • A change in your bowel habits, including diarrhea or constipation or a change in the consistency of your stool, that lasts longer than four weeks
  • Rectal bleeding or blood in your stool
  • Persistent abdominal discomfort, such as cramps, gas or pain
  • A feeling that your bowel doesn’t empty completely
  • Weakness or fatigue
  • Unexplained weight loss

Many people with colon cancer experience no symptoms in the early stages of the disease. When symptoms appear, they’ll likely vary, depending on the cancer’s size and location in your large intestine.

Signs of colon cancer include blood in the stool or a change in bowel habits.

These and other signs and symptoms may be caused by colon cancer or by other conditions. Check with your doctor if you have any of the following:

  • A change in bowel habits.
  • Blood (either bright red or very dark) in the stool.
  • Diarrhea, constipation, or feeling that the bowel does not empty all the way.
  • Stools that are narrower than usual.
  • Frequent gas pains, bloating, fullness, or cramps.
  • Weight loss for no known reason.
  • Feeling very tired.
  • Vomiting.

Colon cancer Diagnosis

Diagnosing colon cancer

If your signs and symptoms indicate that you could have colon cancer, your doctor may recommend one or more tests and procedures, including:

Using a scope to examine the inside of your colon. Colonoscopy uses a long, flexible and slender tube attached to a video camera and monitor to view your entire colon and rectum. If any suspicious areas are found, your doctor can pass surgical tools through the tube to take tissue samples (biopsies) for analysis and remove polyps.

Virtual colonoscopy: A procedure that uses a series of x-rays called computed tomography to make a series of pictures of the colon. A computer puts the pictures together to create detailed images that may show polyps and anything else that seems unusual on the inside surface of the colon. This test is also called colonography or CT colonography.

Sigmoidoscopy: A procedure to look inside the rectum and sigmoid (lower) colon for polyps (small areas of bulging tissue), other abnormal areas, or cancer. A sigmoidoscope is inserted through the rectum into the sigmoid colon. A sigmoidoscope is a thin, tube-like instrument with a light and a lens for viewing. It may also have a tool to remove polyps or tissue samples, which are checked under a microscope for signs of cancer.

Biopsy: The removal of cells or tissues so they can be viewed under a microscope by a pathologist to check for signs of cancer.

Biopsy samples (from colonoscopy or surgery) are sent to the lab where they are looked at closely. Other tests may suggest that colorectal cancer is present, but the only way to be sure is to look at the biopsy samples under a microscope.

If cancer is found, other lab tests may also be done on the biopsy specimens to help better classify the cancer.

  • Gene tests: Doctors may look for specific gene changes in the cancer cells that might affect how the cancer is best treated especially if the cancer has spread (metastasized). For example, doctors now typically test the cells for changes in the KRAS and NRAS and BRAF genes. Some doctors may also test for changes in the BRAF gene. Patients whose cancers have mutations in these genes typically do not benefit from treatment with certain targeted anti-cancer drugs.
  • MSI and MMR testing: Colorectal cancer cells are typically tested to see if they show high levels of gene changes called microsatellite instability (MSI). Testing might also be done to see if the cancer cells have changes in any of the mismatch repair (MMR) genes (MLH1, MSH2, MSH6, and PMS2).

Changes in MSI or in MMR genes (or both) are often seen in people with Lynch syndrome (HNPCC). Most colorectal cancers do not have high levels of MSI or changes in MMR genes. But most colorectal cancers that are linked to Lynch syndrome do.

There are 2 possible reasons to test colorectal cancers for MSI or for MMR gene changes:

  • To identify patients who should be tested for Lynch syndrome. A diagnosis of Lynch syndrome can help plan other cancer screenings for the patient (for example, women with Lynch syndrome may need to be screened for uterine cancer). Also, if a patient has Lynch syndrome, their relatives could also have it, and may want to be tested for it.
  • To determine treatment options for colorectal cancer, where MSI or MMR results could change the way it is treated.

Blood tests. No blood test can tell you if you have colon cancer. But your doctor may test your blood for clues about your overall health, such as kidney and liver function tests.

Your doctor may also test your blood for a chemical sometimes produced by colon cancers called tumor markers that can be found in the blood. The most common tumor markers for colorectal cancer are carcinoembryonic antigen (CEA) and CA 19-9. Tracked over time, the level of CEA in your blood may help your doctor understand your prognosis and whether your cancer is responding to treatment.

Blood tests for these tumor markers can sometimes suggest someone might have colorectal cancer, but they can’t be used alone to screen for or diagnose cancer. This is because tumor marker levels can sometimes be normal in someone who has cancer and can be abnormal for reasons other than cancer.

Tumor markers are used most often along with other tests to monitor patients who already have been diagnosed with colorectal cancer. They may help show how well treatment is working or provide an early warning that a cancer has returned.

If symptoms or the results of the physical exam or blood tests suggest that you might have colorectal cancer, your doctor could recommend more tests. This most often is colonoscopy, but sometimes other tests may be done first.

Barium enema: A series of x-rays of the lower gastrointestinal tract. A liquid that contains barium (a silver-white metallic compound) is put into the rectum. The barium coats the colon and x-rays are taken. This procedure is also called a lower GI series.

Colon cancer stages

Once you’ve been diagnosed with colon cancer, your doctor will order tests to determine the extent and how far the colon cancer has spread. This process is called staging. The stage of a cancer describes how much cancer is in the body. It helps determine how serious the cancer is and how best to treat it. Staging helps determine what treatments are most appropriate for you. Doctors also use a cancer’s stage when talking about survival statistics.

Staging tests may include imaging procedures such as abdominal, pelvic and chest CT scans. In many cases, the stage of your cancer may not be determined until after colon cancer surgery.

The stages of colon cancer are:

  • Stage O (a very early cancer). In stage O, abnormal cells are found in the mucosa (innermost layer) of the colon wall. These abnormal cells may become cancer and spread. Stage 0 is also called carcinoma in situ.
  • Stage I. In stage I, cancer has formed in the mucosa (innermost layer) of the colon wall and has spread to the submucosa (layer of tissue under the mucosa). Cancer may have spread to the muscle layer of the colon wall.
  • Stage II. Stage II colon cancer is divided into stage IIA, stage IIB, and stage IIC.
    • Stage IIA: Cancer has spread through the muscle layer of the colon wall to the serosa (outermost layer) of the colon wall.
    • Stage IIB: Cancer has spread through the serosa (outermost layer) of the colon wall but has not spread to nearby organs.
    • Stage IIC: Cancer has spread through the serosa (outermost layer) of the colon wall to nearby organs.
  • Stage III. Stage III colon cancer is divided into stage IIIA, stage IIIB, and stage IIIC.
    • In stage IIIA:
      • Cancer has spread through the mucosa (innermost layer) of the colon wall to the submucosa (layer of tissue under the mucosa) and may have spread to the muscle layer of the colon wall. Cancer has spread to at least one but not more than 3 nearby lymph nodes or cancer cells have formed in tissues near the lymph nodes; or
      • Cancer has spread through the mucosa (innermost layer) of the colon wall to the submucosa (layer of tissue under the mucosa). Cancer has spread to at least 4 but not more than 6 nearby lymph nodes.
    • In stage IIIB:
      • Cancer has spread through the muscle layer of the colon wall to the serosa (outermost layer) of the colon wall or has spread through the serosa but not to nearby organs. Cancer has spread to at least one but not more than 3 nearby lymph nodes or cancer cells have formed in tissues near the lymph nodes; or
      • Cancer has spread to the muscle layer of the colon wall or to the serosa (outermost layer) of the colon wall. Cancer has spread to at least 4 but not more than 6 nearby lymph nodes; or
      • Cancer has spread through the mucosa (innermost layer) of the colon wall to the submucosa (layer of tissue under the mucosa) and may have spread to the muscle layer of the colon wall. Cancer has spread to 7 or more nearby lymph nodes.
    • In stage IIIC:
      • Cancer has spread through the serosa (outermost layer) of the colon wall but has not spread to nearby organs. Cancer has spread to at least 4 but not more than 6 nearby lymph nodes; or
      • Cancer has spread through the muscle layer of the colon wall to the serosa (outermost layer) of the colon wall or has spread through the serosa but has not spread to nearby organs. Cancer has spread to 7 or more nearby lymph nodes; or
      • Cancer has spread through the serosa (outermost layer) of the colon wall and has spread to nearby organs. Cancer has spread to one or more nearby lymph nodes or cancer cells have formed in tissues near the lymph nodes.
  • Stage IV. The cancer has spread through the blood and lymph nodes to other parts of the body, such as the lung, liver, abdominal wall, or ovary.
  • Stage IV colon cancer is divided into stage IVA and stage IVB.
    • Stage IVA: Cancer may have spread through the colon wall and may have spread to nearby organs or lymph nodes. Cancer has spread to one organ that is not near the colon, such as the liver, lung, or ovary, or to a distant lymph node.
    • Stage IVB: Cancer may have spread through the colon wall and may have spread to nearby organs or lymph nodes. Cancer has spread to more than one organ that is not near the colon or into the lining of the abdominal wall.

As a rule, the lower the number, the less the cancer has spread. A higher number, such as stage IV, means cancer has spread more. And within a stage, an earlier letter means a lower stage. Although each person’s cancer experience is unique, cancers with similar stages tend to have a similar outlook and are often treated in much the same way.

How is the stage determined?

The staging system most often used for colorectal cancer is the American Joint Committee on Cancer TNM system, which is based on 3 key pieces of information:

The extent (size) of the tumor (T): How far has the cancer grown into the wall of the colon or rectum? These layers, from the inner to the outer, include:

  • The inner lining (mucosa), which is the layer in which nearly all colorectal cancers start. This includes a thin muscle layer (muscularis mucosa).
  • The fibrous tissue beneath this muscle layer (submucosa)
  • A thick muscle layer (muscularis propria)
  • The thin, outermost layers of connective tissue (subserosa and serosa) that cover most of the colon but not the rectum

The spread to nearby lymph nodes (N): Has the cancer spread to nearby lymph nodes?

The spread (metastasis) to distant sites (M): Has the cancer spread to distant lymph nodes or distant organs such as the liver or lungs?

The system described below is the most recent American Joint Committee on Cancer system effective January 2018. It uses the pathologic stage (also called the surgical stage) which is determined by examining tissue removed during an operation. This is also known as surgical staging. This is likely to be more accurate than clinical staging, which takes into account the results of a physical exam, biopsies, and imaging tests, done before surgery.

Numbers or letters after T, N, and M provide more details about each of these factors. Higher numbers mean the cancer is more advanced. Once a person’s T, N, and M categories have been determined, this information is combined in a process called stage grouping to assign an overall stage.

Cancer staging can be complex, so ask your doctor to explain it to you in a way you understand.

Table 3. Colon cancer stages

AJCC StageStage groupingStage description*
0Tis

N0

M0

The cancer is in its earliest stage. This stage is also known as carcinoma in situ or intramucosal carcinoma (Tis). It has not grown beyond the inner layer (mucosa) of the colon or rectum.
IT1 or T2

N0

M0

The cancer has grown through the muscularis mucosa into the submucosa (T1), and it may also have grown into the muscularis propria (T2). It has not spread to nearby lymph nodes (N0) or to distant sites (M0).
IIAT3

N0

M0

The cancer has grown into the outermost layers of the colon or rectum but has not gone through them (T3). It has not reached nearby organs. It has not spread to nearby lymph nodes (N0) or to distant sites (M0).
IIBT4a

N0

M0

The cancer has grown through the wall of the colon or rectum but has not grown into other nearby tissues or organs (T4a). It has not yet spread to nearby lymph nodes (N0) or to distant sites (M0).
IICT4b

N0

M0

The cancer has grown through the wall of the colon or rectum and is attached to or has grown into other nearby tissues or organs (T4b). It has not yet spread to nearby lymph nodes (N0) or to distant sites (M0).
 

 

 

 

IIIA

 

T1 or T2

N1/N1c

M0

The cancer has grown through the mucosa into the submucosa (T1), and it may also have grown into the muscularis propria (T2). It has spread to 1 to 3 nearby lymph nodes (N1) or into areas of fat near the lymph nodes but not the nodes themselves (N1c). It has not spread to distant sites (M0).
OR
T1

N2a

M0

The cancer has grown through the mucosa into the submucosa (T1). It has spread to 4 to 6 nearby lymph nodes (N2a). It has not spread to distant sites (M0).
 

 

 

 

 

 

 

IIIB

 

T3 or T4a, N1/N1c

M0

The cancer has grown into the outermost layers of the colon or rectum (T3) or through the visceral peritoneum (T4a) but has not reached nearby organs. It has spread to 1 to 3 nearby lymph nodes (N1a or N1b) or into areas of fat near the lymph nodes but not the nodes themselves (N1c). It has not spread to distant sites (M0).
OR
T2 or T3

N2a

M0

The cancer has grown into the muscularis propria (T2) or into the outermost layers of the colon or rectum (T3). It has spread to 4 to 6 nearby lymph nodes (N2a). It has not spread to distant sites (M0).
OR
T1 or T2 N2b

M0

The cancer has grown through the mucosa into the submucosa (T1), and it may also have grown into the muscularis propria (T2). It has spread to 7 or more nearby lymph nodes (N2b). It has not spread to distant sites (M0).
 

 

 

 

 

 

IIIC

 

T4a

N2a

M0

The cancer has grown through the wall of the colon or rectum (including the visceral peritoneum) but has not reached nearby organs (T4a). It has spread to 4 to 6 nearby lymph nodes (N2a). It has not spread to distant sites (M0).
OR
T3 or T4a

N2b

M0

The cancer has grown into the outermost layers of the colon or rectum (T3) or through the visceral peritoneum (T4a) but has not reached nearby organs. It has spread to 7 or more nearby lymph nodes (N2b). It has not spread to distant sites (M0).
OR
T4b

N1 or N2

M0

The cancer has grown through the wall of the colon or rectum and is attached to or has grown into other nearby tissues or organs (T4b). It has spread to at least one nearby lymph node or into areas of fat near the lymph nodes (N1 or N2). It has not spread to distant sites (M0).
IVAAny T

Any N

M1a

The cancer may or may not have grown through the wall of the colon or rectum (Any T). It might or might not have spread to nearby lymph nodes. (Any N). It has spread to 1 distant organ (such as the liver or lung) or distant set of lymph nodes, but not to distant parts of the peritoneum (the lining of the abdominal cavity) (M1a).
IVBAny T

Any N

M1b

The cancer might or might not have grown through the wall of the colon or rectum (Any T). It might or might not have spread to nearby lymph nodes (Any N). It has spread to more than 1 distant organ (such as the liver or lung) or distant set of lymph nodes, but not to distant parts of the peritoneum (the lining of the abdominal cavity) (M1b).
IVCAny T

Any N

M1c

The cancer might or might not have grown through the wall of the colon or rectum (Any T). It might or might not have spread to nearby lymph nodes (Any N). It has spread to distant parts of the peritoneum (the lining of the abdominal cavity), and may or may not have spread to distant organs or lymph nodes (M1c).

* The following additional categories are not listed in the table above:

  • TX: Main tumor cannot be assessed due to lack of information.
  • T0: No evidence of a primary tumor.
  • NX: Regional lymph nodes cannot be assessed due to lack of information.
[Source 2)]

Recurrent Colon Cancer

Recurrent colon cancer is cancer that has recurred (come back) after it has been treated. The cancer may come back in the colon or in other parts of the body, such as the liver, lungs, or both.

Figure 5. Large intestine anatomy (normal)

layers of large intestine

Figure 6. Colon cancer stages

Colon cancer stages

Note: At its earliest stage (stage 0), colon cancer is limited to the inner lining of your colon. As colon cancer progresses, it can grow through your colon and extend to nearby structures. The most advanced stage of colon cancer (stage IV) indicates cancer has spread to other areas of the body, such as the liver or lungs.

Figure 7. Stage 0 (Carcinoma in Situ)

colon cancer -stage 0 Carcinoma in SituFigure 8. Stage 1

colon cancer - stage 1Figure 9. Stage 2

colon cancer - stage 2

Figure 10. Stage 3

colon cancer - stage 3colon cancer - stage 3Bcolon cancer - stage 3C

Figure 11. Stage 4

colon cancer - stage 4Colon cancer survival rate

Survival rates tell you what portion of people with the same type and stage of cancer are still alive a certain amount of time (usually 5 years) after they were diagnosed. They can’t tell you how long you will live, but they may help give you a better understanding about how likely it is that your treatment will be successful. Some people will want to know the survival rates for their cancer type and stage, and some people won’t. If you don’t want to know, you don’t have to.

What is a 5-year survival rate?

Statistics on the outlook for a certain type and stage of cancer are often given as 5-year survival rates, but many people live longer – often much longer – than 5 years. The 5-year survival rate is the percentage of people who live at least 5 years after being diagnosed with cancer. For example, a 5-year survival rate of 90% means that an estimated 90 out of 100 people who have that cancer are still alive 5 years after being diagnosed. Keep in mind, however, that many of these people live much longer than 5 years after diagnosis.

Relative survival rates are a more accurate way to estimate the effect of cancer on survival. These rates compare people with colorectal cancer to people in the overall population. For example, if the 5-year relative survival rate for a specific type and stage of cancer is 90%, it means that people who have that cancer are, on average, about 90% as likely as people who don’t have that cancer to live for at least 5 years after being diagnosed.

But remember, the 5-year relative survival rates are estimates – your outlook can vary based on a number of factors specific to you.

Cancer survival rates don’t tell the whole story

Survival rates are often based on previous outcomes of large numbers of people who had the disease, but they can’t predict what will happen in any particular person’s case. There are a number of limitations to remember:

  • The numbers below are among the most current available. But to get 5-year survival rates, doctors have to look at people who were treated at least 5 years ago. As treatments are improving over time, people who are now being diagnosed with colorectal cancer may have a better outlook than these statistics show.
  • These statistics are based on the stage of the cancer when it was first diagnosed. They do not apply to cancers that later come back or spread, for example.
  • The outlook for people with colorectal cancer varies by the stage (extent) of the cancer – in general, the survival rates are better for people with earlier stage cancers. But many other factors can affect a person’s outlook, such as age and overall health, and how well the cancer responds to treatment. The outlook for each person is specific to his or her circumstances.

Your doctor can tell you how these numbers may apply to you, as he or she is familiar with your particular situation.

Colon cancer survival rates, by stage

The numbers below come from the National Cancer Institute’s SEER database, looking at people diagnosed with colon cancer between 2004 and 2010 3).

  • The 5-year relative survival rate for people with stage I colon cancer is about 92%.
  • For people with stage IIA colon cancer, the 5-year relative survival rate is about 87%. For stage IIB cancer, the survival rate is about 63%.
  • The 5-year relative survival rate for stage IIIA colon cancers is about 89%. For stage IIIB cancers the survival rate is about 69%, and for stage IIIC cancers the survival rate is about 53%.
  • Colon cancers that have spread to other parts of the body are often harder to treat and tend to have a poorer outlook. Metastatic, or stage IV colon cancers, have a 5-year relative survival rate of about 11%. Still, there are often many treatment options available for people with this stage of cancer.

These statistics are based on a previous version of the TNM staging system. In that version, there was no stage IIC (those cancers were considered stage IIB). Also, some cancers that are now considered stage IIIC were classified as stage IIIB, while some other cancers that are now considered stage IIIB were classified as stage IIIC.

Remember, these survival rates are only estimates – they can’t predict what will happen to any individual person. We understand that these statistics can be confusing and may lead you to have more questions. Talk to your doctor to better understand your specific situation.

Rectal cancer survival rates, by stage

The numbers below come from the National Cancer Institute’s SEER database, looking at people diagnosed with rectal cancer between 2004 and 2010.

  • The 5-year relative survival rate for people with stage I rectal cancer is about 87%.
  • For people with stage IIA rectal cancer, the 5-year relative survival rate is about 80%. For stage IIB cancer, the survival rate is about 49%.
  • The 5-year relative survival rate for stage IIIA rectal cancers is about 84%. For stage IIIB cancers the survival rate is about 71%, and for stage IIIC cancers the survival rate is about 58%.
  • Rectal cancers that have spread to other parts of the body are often harder to treat and tend to have a poorer outlook. Metastatic, or stage IV rectal cancers, have a 5-year relative survival rate of about 12%. Still, there are often many treatment options available for people with this stage of cancer.

These statistics are based on a previous version of the TNM staging system. In that version, there was no stage IIC (those cancers were considered stage IIB). Also, some cancers that are now considered stage IIIC were classified as stage IIIB, while some other cancers that are now considered stage IIIB were classified as stage IIIC.

Remember, these survival rates are only estimates – they can’t predict what will happen to any individual person. We understand that these statistics can be confusing and may lead you to have more questions. Talk to your doctor to better understand your specific situation.

Colon cancer treatment

The type of treatment your doctor recommends will depend largely on the stage of your cancer. The three primary treatment options are surgery, chemotherapy and radiation.

Surgery for early-stage colon cancer

If your colon cancer is very small, your doctor may recommend a minimally invasive approach to surgery, such as:

  • Removing polyps during a colonoscopy. If your cancer is small, localized and completely contained within a polyp and in a very early stage, your doctor may be able to remove it completely during a colonoscopy.
  • Endoscopic mucosal resection. Removing larger polyps may require also taking a small amount of the lining of the colon or rectum in a procedure called an endoscopic mucosal resection.
  • Minimally invasive surgery. Polyps that can’t be removed during a colonoscopy may be removed using laparoscopic surgery. In this procedure, your surgeon performs the operation through several small incisions in your abdominal wall, inserting instruments with attached cameras that display your colon on a video monitor. The surgeon may also take samples from lymph nodes in the area where the cancer is located.

Surgery for invasive colon cancer

If the cancer has grown into or through your colon, your surgeon may recommend:

  • Partial colectomy. During this procedure, the surgeon removes the part of your colon that contains the cancer, along with a margin of normal tissue on either side of the cancer. Your surgeon is often able to reconnect the healthy portions of your colon or rectum. This procedure can commonly be done by a minimally invasive approach (laparoscopy).
  • Surgery to create a way for waste to leave your body. When it’s not possible to reconnect the healthy portions of your colon or rectum, you may need an ostomy. This involves creating an opening in the wall of your abdomen from a portion of the remaining bowel for the elimination of stool into a bag that fits securely over the opening. Sometimes the ostomy is only temporary, allowing your colon or rectum time to heal after surgery. In some cases, however, the colostomy may be permanent.
  • Lymph node removal. Nearby lymph nodes are usually also removed during colon cancer surgery and tested for cancer.

Surgery for advanced cancer

If your cancer is very advanced or your overall health very poor, your surgeon may recommend an operation to relieve a blockage of your colon or other conditions in order to improve your symptoms. This surgery isn’t done to cure cancer, but instead to relieve signs and symptoms, such as bleeding and pain.

In specific cases where the cancer has spread only to the liver but your overall health is otherwise good, your doctor may recommend surgery to remove the cancerous lesion from your liver. Chemotherapy may be used before or after this type of surgery. This approach provides a chance to be free of cancer over the long term.

Chemotherapy

Chemotherapy uses drugs to destroy cancer cells. Chemotherapy for colon cancer is usually given after surgery if the cancer has spread to lymph nodes. In this way, chemotherapy may help reduce the risk of cancer recurrence and death from cancer. Sometimes chemotherapy may be used before surgery as well, with the goal of shrinking the cancer before an operation. Chemotherapy before surgery is more common in rectal cancer than in colon cancer.

Chemotherapy can also be given to relieve symptoms of colon cancer that has spread to other areas of the body.

Radiation therapy

Radiation therapy uses powerful energy sources, such as X-rays, to kill cancer cells, to shrink large tumors before an operation so that they can be removed more easily, or to relieve symptoms of colon cancer and rectal cancer. Radiation therapy either alone or combined with chemotherapy is one of the standard treatment options for the initial management of rectal cancer followed by surgery.

Targeted drug therapy

Drugs that target specific malfunctions that allow cancer cells to grow are available to people with advanced colon cancer, including:

  • Bevacizumab (Avastin)
  • Cetuximab (Erbitux)
  • Panitumumab (Vectibix)
  • Ramucirumab (Cyramza)
  • Regorafenib (Stivarga)
  • Ziv-aflibercept (Zaltrap)

Targeted drugs can be given along with chemotherapy or alone. Targeted drugs are typically reserved for people with advanced colon cancer.

Some people are helped by targeted drugs, while others are not. Researchers have recently made progress in determining who is most likely to benefit from specific targeted drugs. Until more is known, doctors carefully weigh the possible benefit of targeted drugs against the risk of side effects and the cost when deciding whether to use these treatments.

Immunotherapy

Some patients with advanced colon cancer have a chance to benefit from immunotherapy with antibodies such as pembrolizumab (Keytruda) and nivolumab (Opdivo). Whether a colon cancer has the chance to respond to these immunotherapies can be determined by a specific test of the tumor tissue.

Supportive (palliative) care

Palliative care is specialized medical care that focuses on providing relief from pain and other symptoms of a serious illness. Palliative care specialists work with you, your family and your other doctors to provide an extra layer of support that complements your ongoing care.

When palliative care is used along with all of the other appropriate treatments, people with cancer may feel better and live longer.

Palliative care is provided by a team of doctors, nurses and other specially trained professionals. Palliative care teams aim to improve the quality of life for people with cancer and their families. This form of care is offered alongside curative or other treatments you may be receiving.

Coping and support

A cancer diagnosis can be emotionally challenging. In time, people learn to cope in their own unique ways. Until you find what works for you, you might try to:

Know what to expect. Learn enough about your cancer to feel comfortable making treatment decisions.

Ask your doctor to tell you the type and stage of your cancer, as well as your treatment options and their side effects. The more you know, the more confident you’ll be when it comes to making decisions about your own care. Look for information in your local library and on reliable websites.
Keep friends and family close. Keeping your close relationships strong will help you deal with cancer. Friends and family can provide the practical support you’ll need, such as helping take care of your house if you’re in the hospital. And they can serve as emotional support when you feel overwhelmed by cancer.

Find someone to talk with. Find a good listener who is willing to listen to you talk about your hopes and fears. This may be a friend or family member. The concern and understanding of a counselor, medical social worker, clergy member or cancer support group also may be helpful.

Ask your doctor about support groups in your area. Or check your phone book, library or a cancer organization, such as the National Cancer Institute or the American Cancer Society.

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