anal cancer

What causes anal cancer

Anal cancer is a disease in which cancer cells form in the tissues of the anus – the very end of the large bowel.

Anal cancer is rare – much less common than cancer of the colon or rectum. It is more common in smokers and people over 50. You are also at higher risk if you have HPV, have anal sex, or have many sexual partners.

The American Cancer Society estimates for anal cancer in the United States for 2018 are:

  • About 8,580 new cases (5,620 in women and 2,960 in men)
  • About 1,160 deaths (680 in women and 480 in men)

The number of new anal cancer cases has been rising for many years. Anal cancer is rare in people younger than 35 and is found mainly in older adults, with an average age being in the early 60s.

The risk of being diagnosed with anal cancer during one’s lifetime is about 1 in 500. The risk is slightly higher in women than in men. The risk is also higher in people with certain risk factors for anal cancer.

Symptoms include rectal bleeding, anal pain or lumps in the anal area. Anal itching and discharge can also be signs of anal cancer.

Doctors use tests that examine the anus to diagnose anal cancer. They include a physical exam, endoscopy, ultrasound, and biopsy.

Treatments include radiation therapy, chemotherapy, and surgery.

Most people with anal cancer are treated with a combination of chemotherapy and radiation (chemoradiation). Though combining anal cancer treatments increases the chance of a cure, the combined treatments also increase the risk of side effects.

The anus

The anus is is the continuation of the large intestine inferior to the rectum. It’s where the end of the intestines connect to the outside of the body.

The anal canal is about 1-1/2 inches long, it begins where the rectum passes through the levator ani, the muscle that forms the pelvic floor. At its distal end, the anal canal opens to the outside skin at the anus.

As food is digested, it passes from the stomach to the small intestine. It then moves from the small intestine into the main part of the large intestine (called the colon). The colon absorbs water and salt from the digested food. The waste matter that’s left after going through the colon is known as feces or stool. Stool is stored in the last part of the large intestine, called the rectum. From there, stool is passed out of the body through the anus as a bowel movement.

The inner lining of the anal canal is the mucosa. Most anal cancers start from cells in the mucosa.

Glands and ducts (tubes leading from the glands) are found under the mucosa. The glands make mucus, which acts as a lubricating fluid. Anal cancers that start from cells in the glands are called adenocarcinomas.

The anal canal changes as it goes from the rectum to the anal verge:

  • Cells above the anal canal (in the rectum) and in the part of the anal canal close to the rectum are shaped like tiny columns.
  • Most cells near the middle of the anal canal are shaped like cubes and are called transitional cells. This area is called the transitional zone.
  • About midway down the anal canal is the dentate line, which is where most of the anal glands empty into the anus.
  • Below the dentate line are flat (squamous) cells.
  • At the anal verge, the squamous cells of the lower anal canal merge with the skin just outside the anus. This skin around the anal verge (called the perianal skin or the anal margin) is also made up of squamous cells, but it also contains sweat glands and hair follicles, which are not found in the lining of the lower anal canal.

Figure 1. Rectum


Figure 2. Rectum anatomy and Anus (anal canal)

anal canal

Anal cancers are often divided into 2 groups, which are sometimes treated differently:

  1. Cancers of the anal canal (above the anal verge)
  2. Cancers of the anal margin (below the anal verge)

Sometimes anal cancers extend from one area into the other, so it’s hard to know exactly where they started.

The anal canal is surrounded by a sphincter, which is a circular muscle that keeps stool from coming out until it relaxes during a bowel movement.

Types of anal cancer

Carcinoma in situ

Sometimes abnormal cells on the inner surface layer of the anus look like cancer cells but have not grown into any of the deeper layers. This is known as carcinoma in situ or CIS. Another name for this is Bowen disease.

Some doctors see this as the earliest form of anal cancer. Others consider it the most advanced type of anal intraepithelial neoplasia (AIN), which is a pre-cancer, but not a true cancer.

Invasive anal cancers

These are the different types of cancer that can start in the anal region:

Squamous cell carcinomas

Most anal cancers in the United States are squamous cell carcinomas. (Nearly 9 out of 10 cases.) These tumors start in the squamous cells that line most of the anal canal and the anal margin.

Squamous cell carcinomas in the anal canal have grown beyond the surface and into the deeper layers of the lining (as opposed to carcinoma in situ which is only in the surface cells).

Cloacogenic carcinomas (also called basaloid or transitional cell carcinomas) are a type of squamous cell cancer. They develop in the transitional zone, also called the cloaca. These cancers look slightly different under a microscope, but they behave and are treated like other squamous cell carcinomas of the anal canal.

Squamous cell carcinomas of the anal margin (perianal skin) are treated much like squamous cell carcinomas of the skin elsewhere.


A small number of anal cancers are known as adenocarcinomas. These start in cells that line the upper part of the anus near the rectum. They can also start in the glands under the anal mucosa that release secretions into the anal canal. Most anal adenocarcinomas are treated the same as rectal carcinomas.

Adenocarcinomas can also start in apocrine glands (a type of sweat gland of the perianal skin). Paget’s disease is a type of apocrine gland carcinoma that spreads through the surface layer of the skin. Paget’s disease can affect skin anywhere in the body but most often affects skin of the perianal area, vulva, or breast. This should not be confused with Paget’s disease of the bone , which is not cancer and a different disease.

Basal cell carcinomas

Basal cell carcinomas are a type of skin cancer that can develop in the perianal skin. These tumors are much more common in areas of skin exposed to the sun, such as the face and hands, and account for very few anal cancers. They are often treated with surgery to remove the cancer.


These cancers start in cells in the skin or anal lining that make the brown pigment called melanin. Only a very small portion of anal cancers are melanomas. Melanomas are far more common on the skin in other parts of the body. If melanomas are found at an early stage (before they have grown deeply into the skin or spread to lymph nodes) they can be removed with surgery, and the outlook for long-term survival is very good. But because anal melanomas are hard to see, most are found at a later stage. If possible, the entire tumor is removed with surgery. If all of the tumor can be removed, a cure is possible. If the melanoma has spread too far to be removed completely, other treatments may be given.

Gastrointestinal stromal tumors (GISTs)

These cancers are much more common in the stomach or small intestine, but rarely they can start in the anal region. When these tumors are found at an early stage, they are removed with surgery. If they have spread beyond the anus, they can be treated with drug therapy.

Potentially pre-cancerous anal conditions

Some changes in the anal mucosa are harmless at first, but might later develop into a cancer. These are called pre-cancerous conditions. A common term for these potentially pre-cancerous conditions is dysplasia. Some warts, for example, contain areas of dysplasia that can develop into cancer.

Dysplasia in cells of the anus is also called anal intraepithelial neoplasia (AIN) or anal squamous intraepithelial lesions (SILs). Depending on how the cells look, AIN or anal SIL can be divided into 2 groups:

Low-grade AIN (sometimes called AIN1 or low-grade anal SIL)

  • The cells in low-grade AIN look like normal cells in many ways.
  • Low-grade AIN often goes away without treatment. It has a low chance of turning into cancer.

High-grade AIN (sometimes called AIN2 or AIN3, or high-grade anal SIL)

  • The cells in high-grade AIN look much more abnormal.
  • High-grade AIN is less likely to go away without treatment and, with time, could become cancer. It needs to be watched closely. Some cases of high-grade AIN need to be treated.

Anal cancer complications

Anal cancer rarely spreads (metastasizes) to distant parts of the body. Only a small percentage of tumors are found to have spread, but those that do are especially difficult to treat. Anal cancer that metastasizes most commonly spreads to the liver and the lungs.

Anal cancer causes

The exact cause of anal cancer is unknown, although a number of factors can increase your risk of developing the condition. These include:

  • Infection with human papilloma virus (HPV) – a common and usually harmless group of viruses spread through sexual contact, which can affect the moist membranes lining your body
  • Having anal sex or lots of sexual partners – possibly because this increases your risk of developing HPV
  • Having a history of cervical, vaginal or vulval cancer
  • Smoking
  • Having a weakened immune system – for example, if you have HIV. HIV — the virus that causes AIDS — suppresses the immune system and increases the risk of anal cancer.
  • Drugs or conditions that suppress your immune system. People who take drugs to suppress their immune systems (immunosuppressive drugs), including people who have received organ transplants, may have an increased risk of anal cancer.

Your risk of developing anal cancer increases as you get older, with half of all cases diagnosed in people aged 65 or over. The condition is also slightly more common in women than men.

  • HPV infection

Most anal cancers seem to be linked to infection with the human papillomavirus (HPV). While HPV infection seems to be important in the development of anal cancer, the vast majority of people with HPV infections do not get anal cancer.

Most squamous cell anal cancers are linked to infection with the human papillomavirus (HPV), the same virus that causes cervical cancer, as well as many other kinds of cancer. In fact, women with a history of cervical cancer (or pre-cancer) have an increased risk of anal cancer. They are called papillomaviruses because some of them cause papillomas, which are more commonly known as warts. The 2 types of HPV that cause most cases of anal and genital warts are HPV-6 and HPV-11.

HPV is a group of more than 150 related viruses. The subtype known as HPV-16 is often found in squamous cell carcinoma and is also found in some anal warts. Another subtype, HPV-18, is found less often. Most anal warts are caused by HPV-6 and HPV-11. Warts containing HPV-6 or HPV-11 are much less likely to become cancerous than those containing HPV-16. While anal warts themselves are unlikely to develop into anal cancer, people who have had anal warts are more likely to get anal cancer. This is because people who are infected with HPV subtypes that cause anal and genital warts are also more likely to be infected HPV subtypes that cause anal cancer.

HPV makes proteins (E6 and E7) that can shut down 2 important tumor suppressor proteins in normal cells. These proteins – p53 and Rb – normally work to keep cells from growing out of control. When these proteins are not active, cells are more likely to become cancerous.

HPV is passed from one person to another during skin-to-skin contact with an infected area of the body. HPV can be spread during sexual activity – including vaginal, anal, and oral sex – but sex doesn’t have to occur for the infection to spread. All that’s needed is for there to be skin-to-skin contact with an area of the body infected with HPV. The virus can be spread through genital-to-genital contact, or even hand-to-genital contact. An HPV infection can also spread from one part of the body to another. For example, an HPV infection might start in the genitals and then spread to the anus.

It can be very hard to avoid being exposed to HPV. It might be possible to prevent genital HPV infection by not allowing others to have contact with your anal or genital area, but even then there could be other ways to become infected that aren’t yet clear.

Infection with HPV is common, and in most cases the body can clear the infection on its own. But in some people the infection doesn’t go away and becomes chronic. Chronic infection, especially with high-risk HPV types, can cause certain cancers over time, including anal cancer.

A great deal of research is now being done to learn how HPV might cause anal cancer. There is good evidence that HPV causes many anal squamous cell carcinomas. But the role of this virus in causing anal adenocarcinomas is less certain.

  • Lowered immunity

When the body is less able to fight off infections, viruses like HPV can become more active, which might trigger the development of anal cancer. HIV, the virus that causes AIDS, weakens the body’s immune system, as can medicines used to prevent rejection in patients with organ transplants.

  • Smoking

Most people know that smoking is the main cause of lung cancer. But few realize that the cancer-causing chemicals in tobacco smoke can travel from the lungs to the rest of the body, causing other types of cancer. Smoking also seems to make the immune system less effective in fighting HPV infections. Many studies have noted an increased rate of anal cancer in smokers, and the effect of smoking is especially important in people with other risk factors for anal cancer.

It’s important to remember that some people with anal cancers do not have any known risk factors and the causes of their cancers are not known.

Risk Factors for Anal Cancer

Several factors can affect your risk of anal cancer. But having a risk factor, or even several risk factors, does not mean that you will get cancer. Many people with risk factors never develop anal cancer, while others with this disease may have few or no known risk factors.

  • Human papillomavirus (HPV) infection
  • Having certain other cancers

Women who have had cancer of the cervix, vagina, or vulva are at increased risk of anal cancer. This is probably because these cancers are also caused by infection with HPV.

In men, it would seem likely that having had penile cancer, which is also linked to HPV infection, would increase the risk of anal cancer, but this link has not been shown in studies.

  • HIV infection

People infected with the human immunodeficiency virus (HIV), the virus that causes AIDS, are much more likely to get anal cancer than those not infected with this virus.

  • Sexual activity

Having multiple sex partners increases the risk of infection with HIV and HPV. It also increases the risk of anal cancer.

Receptive anal sex also increases the risk of anal cancer in both men and women. Because of this, men who have sex with men have a high risk of this cancer.

  • Smoking

Smoking increases the risk of anal cancer. Current smokers are several times more likely to have cancer of the anus compared with people who do not smoke. Quitting smoking seems to reduce the risk. People who used to smoke but have quit are only slightly more likely to develop this cancer compared with people who never smoked.

  • Lowered immunity

Higher rates of anal cancer occur among people with reduced immunity, such as people with AIDS or people who have had an organ transplant and must take medicines that suppress their immune system.

  • Gender and race/ethnicity

Anal cancer is more common in women than men overall, but this varies in racial/ethnic groups and can vary with age. For instance, in African Americans younger than age 60, it’s more common in men than in women, but after age 60 it’s more common in women.

Anal cancer prevention

Since the cause of many cases of anal cancer is unknown, it’s not possible to prevent this disease completely. But there are things you can do that might lower your risk of anal cancer.

Infection with HPV increases the risk of anal cancer. HPV infection can be present for years without causing any symptoms, so the absence of visible warts can’t be used to tell if someone has HPV. Even when someone doesn’t have warts (or any other symptom), he (or she) can still be infected with HPV and pass it on to somebody else.

In order to reduce your risk of anal cancer:

  • Practice safer sex. Abstaining from sex or practicing safe sex may help prevent HPV and HIV, two sexually transmitted viruses that may increase your risk of anal cancer. If you choose to have anal sex, use condoms.
  • Get vaccinated against HPV. Two vaccines — Gardasil and Cervarix — are given to protect against HPV infection. Both boys and girls can be vaccinated against HPV.
  • Stop smoking. Smoking increases your risk of anal cancer. Don’t start smoking. Stop if you currently smoke.

HPV vaccines

Vaccines are available that protect against certain HPV infections. They protect against infection with HPV subtypes 16 and 18. Some can also protect against infections with other HPV subtypes, including some types that cause anal and genital warts.

These vaccines can only be used to help prevent HPV infection – they do not help treat an existing infection. To work best, the vaccine should be given before a person becomes sexually active.

Condom use

Condoms may provide some protection against HPV (and HIV), but they don’t prevent infection completely.

One study found that when condoms are used correctly they can lower the genital HPV infection rate in women – but they must be used every time sex occurs. This study did not look at the effect of condom use on anal HPV infection.

Condoms can’t protect completely because they don’t cover every possible HPV-infected area of the body, such as skin of the genital or anal area. HPV can still be passed from one person to another by skin to skin contact with an HPV-infected area of the body that is not covered by a condom. Still, condoms may provide some protection against HPV. Male condom use also seems to help genital HPV infections clear (go away) faster in both women and men.

Condom use is also important because it can help protect against AIDS and other sexually transmitted illnesses that can be passed on through some body fluids.

Treating HIV

For people infected with HIV, it’s very important to take medicines (known as highly active antiretroviral therapy, or HAART) to help keep the infection under control and prevent it from progressing to AIDS. This also lowers the risk of long-term HPV infection and anal intraepithelial neoplasia (a kind of anal pre-cancer), which might help lower the risk of anal cancer.

Not smoking

Smoking is a known risk factor for anal cancer. Stopping smoking greatly reduces the risk of developing anal cancer and many other cancers.

Screening in people at high risk

Looking for a disease like cancer in someone with no symptoms is called screening. The goal of screening is to find cancer at an early stage, when treatment is likely to be most helpful. Anal cancer is not common in the United States, so screening the general public for anal cancer is not widely recommended at this time.

Still, some people at increased risk for anal intraepithelial neoplasia (AIN, a potentially pre-cancerous condition) and anal cancer might benefit from screening. This includes men who have sex with men (regardless of HIV status), women who have had cervical cancer or vulvar cancer, anyone who is HIV-positive, and anyone who has received an organ transplant. Some experts also recommend screening for anyone with a history of anal warts.

For these people, some experts recommend screening with regular digital rectal examinations and anal cytology testing (also known as an anal Pap test or anal Pap smear because it is much like a Pap test for cervical cancer). For an anal Pap test, the anal lining is swabbed, and cells that come off on the swab are looked at under the microscope.

The anal Pap test has not been studied enough to know how often it should be done, or if it actually reduces the risk of anal cancer by catching intraepithelial neoplasia (AIN) early. Some experts recommend that the test be done every year in men who have sex with men who are HIV-positive, and every 2 to 3 years if the men are HIV-negative. But there is no widespread agreement on the best screening schedule, or even exactly which groups of people can benefit from screening.

Patients with positive results on an anal Pap test should be referred for a biopsy. If AIN is found on the biopsy, it might need to be treated (especially if it is high-grade).

Anal cancer signs and symptoms

The symptoms of anal cancer are often similar to more common and less serious conditions affecting the anus, such as piles (hemorrhoids) and anal fissures (small tears or sores).

Sometimes anal cancer causes no symptoms at all. But bleeding is often the first sign of the disease. The bleeding is usually minor. At first, most people assume the bleeding is caused by hemorrhoids (painful, swollen veins in the anus and rectum that may bleed). They are a benign and fairly common cause of rectal bleeding.

Symptoms of anal cancer can include:

  • bleeding from the bottom (rectal bleeding)
  • itching and pain around the anus
  • small lumps around the anus
  • a discharge of mucus from the anus
  • loss of bowel control (bowel incontinence)
  • swollen lymph nodes in the anal or groin areas

However, some people with anal cancer don’t have any symptoms.

See your doctor if you develop any of the above symptoms. While they’re unlikely to be caused by anal cancer, it’s best to get them checked out.

Anal cancer diagnosis

Tests and procedures used to diagnose anal cancer include:

  • Examining your anal canal and rectum for abnormalities. During a digital rectal exam, your doctor inserts a gloved, lubricated finger into your rectum. He or she feels for anything unusual, such as growths.
  • Visually inspecting your anal canal and rectum. Your doctor may use a short, lighted tube (anoscope) to inspect your anal canal and rectum for anything unusual.
  • Taking sound wave pictures (ultrasound) of your anal canal. To create a picture of your anal canal, your doctor inserts a probe, similar to a thick thermometer, into your anal canal and rectum. The probe emits high-energy sound waves, called ultrasound waves, which bounce off tissues and organs in your body to create a picture. Your doctor evaluates the picture to look for anything abnormal.
  • Removing a sample of tissue for laboratory testing. If your doctor discovers any unusual areas, he or she may take small samples of affected tissue (biopsy) and send the samples to a laboratory for analysis. By looking at the cells under a microscope, doctors can determine whether the cells are cancerous.


Endoscopy uses a thin tube with a lens or tiny video camera on the end to look inside part of the body. Many types of endoscopy can be used to look for the cause of anal symptoms. They can also be used to get tissue samples from inside the anal canal (described below under Biopsy). Drugs may be used to make you sleepy during these tests.


For anoscopy the doctor uses a short, hollow tube called an anoscope. It’s 3 to 4 inches long and about 1 inch in diameter and may have a light on the end of it. The doctor coats the anoscope with a lubricant and then gently pushes it into the anus and rectum. By shining a light into this tube, the doctor has a clear view of the lining of the lower rectum and anus. This exam usually doesn’t hurt.

Rigid proctosigmoidoscopy

The rigid proctosigmoidoscope is a lot like an anoscope, except that it’s longer (about 10 inches long). It lets the doctor see the rectum and the lower part of the sigmoid colon. You might need to take laxatives or have an enema before this test to make sure your bowels are empty.


Ultrasound uses sound waves to make pictures of internal organs or masses. This test can be used to see how deep the cancer has grown into the tissues near the anus.

For most ultrasound exams a wand-like transducer is moved around on the skin. But for anal cancer, the transducer is put right into the rectum. This is called a transrectal or endorectal ultrasound. The test can be uncomfortable, but it usually doesn’t hurt.


If a change or growth is seen during an endoscopic exam, your doctor will need to take out a piece of it to see if it’s cancer. This is called a biopsy. If the growth is in the anal canal, this can often be done through the scope itself. Drugs may be used to numb the area before the biopsy is taken. Then, a small piece of the tissue is cut out and sent to a lab. If the tumor is very small, your doctor might try to remove the entire tumor during the biopsy.

A doctor called a pathologist will look at the tissue sample under a microscope. If cancer is present, the pathologist will send back a report describing the cell type and extent of the cancer.

Anal cancer sometimes spreads to nearby lymph nodes (bean-sized collections of immune system cells). Swollen lymph nodes in the groin can be a sign that cancer has spread. Lymph nodes may also become swollen from an infection. Biopsies may be needed to check for cancer spread to nearby lymph nodes.

There are many different ways to do a biopsy. A type called fine-needle aspiration (FNA) is often used to check lymph nodes that might have cancer in them. To do this, a small sample of fluid and tissue is taken out of the lymph node using a thin, hollow needle. A pathologist checks this fluid for cancer cells. If cancer is found in a lymph node, surgery may be done to remove the lymph nodes in that area.

Determining the extent of the cancer

Once it’s confirmed that you have anal cancer, your doctor may recommend additional tests to determine whether your cancer has spread to your lymph nodes or to other areas of your body.

Tests may include:

  • Computerized tomography (CT)
  • Magnetic resonance imaging (MRI)
  • Positron emission tomography (PET)

Computed tomography (CT) scan

CT scans use x-rays to make detailed cross-sectional images of your body. This is a common test for people with anal cancer. It can be used to help tell if the cancer has spread into the lymph nodes or to other parts of the body, such as the liver, lungs, or other organs.

Instead of taking one picture, like a standard x-ray, a CT scanner takes many pictures as it rotates around you. A computer then combines these into an image of a slice of your body.

CT-guided needle biopsy: CT scans can also be used to guide a biopsy needle right into a change that could be cancer. To do this, you stay on the CT scanning table while the doctor moves a biopsy needle through your skin and toward the tumor. CT scans are repeated until the needle is in the tumor. A biopsy sample is then taken out and sent to a lab to be looked at under a microscope.

Magnetic resonance imaging (MRI)

MRI scans use radio waves and strong magnets instead of x-rays. The energy from the radio waves is absorbed by the body and then released in a specific pattern formed by the type of tissue and by certain diseases. A computer translates the pattern into detailed images of parts of the body.

This test is sometimes used to see if nearby lymph nodes are enlarged, which might be a sign the cancer has spread there.

Chest x-ray

A regular x-ray might be done to find out if the cancer has spread to the lungs. It isn’t needed if a CT scan of the chest is done.

Positron emission tomography (PET) scan

For a PET scan, a form of radioactive sugar (known as fluorodeoxyglucose or FDG) is injected into your blood. Cancer cells are very active, so they absorb large amounts of the radioactive sugar. After about an hour, you’ll be moved onto a table in the PET scanner. A special camera creates pictures of areas where the radioactivity has collected. The picture is not finely detailed like a CT or MRI scan, but it provides helpful information about your whole body.

Often a PET scan is done in a machine that can do a CT scan at the same time (a PET/CT scan). It lets the doctor compare areas of higher radioactivity on the PET scan with the more detailed image of that area on the CT scan.

Your doctor uses the information from the procedures to assign your cancer a stage. The stages of anal cancer are indicated using Roman numerals ranging from 0 to IV, with the lowest stages indicating that the cancer is small and confined to the anus. By stage IV, the cancer has spread to distant areas of the body.

The cancer staging system continues to evolve and is becoming more complex as doctors improve cancer diagnosis and treatment. Your doctor uses your cancer stage to select the treatments that are right for you.

Anal Cancer Stages

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

  • The extent (size) of the tumor (T): What is the size of the cancer? Has the cancer reached nearby structures or organs?
  • 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?

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.

Anal cancer is usually staged based on the results of a physical exam, biopsy, and imaging tests. This is called a clinical stage. If surgery is done, the pathologic stage (also called the surgical stage) is determined by examining tissue removed during an operation. This is also known as surgical staging.

The system described below is the most recent AJCC system effective January 2018. It is used for tumors in the anal canal and perianal (formally anal margin) area.

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

AJCC StageStage groupingStage description*




The cancer is only in the mucosa (the top layer of cells lining the inside of the anus). It has not started growing into the deeper layers. (Tis). It has not spread to nearby lymph nodes (N0) or distant sites (M0).
I          T1



The cancer is 2 cm (about 4/5 inch) across or smaller (T1). It has not spread to nearby lymph nodes (N0) or to distant sites (M0).
IIA          T2



The cancer is more than 2 cm (4/5 inch) but not more than 5 cm (about 2 inches) across (T2). The cancer has not spread to nearby lymph nodes (N0) or to distant sites (M0).



The cancer is larger than 5 cm (about 2 inches) across (T3). It has not spread to nearby lymph nodes (N0) or to distant sites (M0).







The cancer is 2 cm (about 4/5 inch) across or smaller (T1) AND it has spread to lymph nodes near the rectum (N1) but not to distant sites (M0).



The cancer is more than 2 cm (4/5 inch) but not more than 5 cm (about 2 inches) across (T2) AND it has spread to lymph nodes near the rectum.

(N1) but not to distant sites (M0).




The cancer is any size and is growing into nearby organ(s), such as the vagina, urethra (the tube that carries urine out of the bladder), prostate gland, or bladder (T4). It has not spread to nearby lymph nodes (N0) or to distant sites (M0).



The cancer is larger than 5 cm (about 2 inches) across (T3) AND it has spread to lymph nodes near the rectum (N1) but not to distant sites (M0).



The cancer is any size and is growing into nearby organ(s), such as the vagina, urethra (the tube that carries urine out of the bladder), prostate gland, or bladder (T4) AND it has spread to lymph nodes near the rectum (N1) but not to distant sites (M0).

Any N


The cancer can be any size and may or may not have grown into nearby organs (any T). It may or may not have spread to nearby lymph nodes (any N). It has spread to distant organs such as the liver or lungs (M1).

*The following additional categories are not listed on 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.

Anal Cancer Survival Rates

Survival rates tell you what percentage of people with the same type and stage of cancer are still alive a certain length of time (usually 5 years) after they were diagnosed.

Remember, 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.

The following statistics come from the National Cancer Data Base and are based on cancers diagnosed between 2003 and 2006. In addition to dividing the cancers by stage, the National Cancer Database divides anal cancers based on histology (how the cells look under the microscope) into squamous cell cancers and non-squamous cell cancers.

These numbers are observed survival rates. They include people diagnosed with anal cancer who might have died later from other causes, such as heart disease. Some people with anal cancer may have other serious health conditions. Therefore, the percentage of people surviving the cancer itself is likely to be higher.

5-year observed survival for anal cancer
StageSquamous cancersNon-squamous cancers

Anal cancer treatment

If you’re diagnosed with anal cancer, you’ll be cared for by a multidisciplinary team. This is a team of different specialists who work together to provide the best treatment and care.

Often the best approach combines 2 or more of these strategies. In the past, surgery was the only way to cure anal cancer, but now most anal cancers are treated with radiation and chemotherapy combined (called chemoradiation or chemoradiotherapy). When this is done, surgery is often not needed.

Your treatment options depend on many factors. The location, type, and the stage (extent of spread) of the tumor are important. In choosing your treatment plan, you and your cancer care team will also take into account your age, your overall health, and your personal preferences.

The main treatments used for anal cancer are:

  • chemoradiation – a combination of chemotherapy and radiotherapy
  • surgery – to remove a tumour or a larger section of bowel

In cases where the cancer has spread and can’t be cured, chemotherapy alone may be considered to help relieve symptoms. This is known as palliative care.

The main treatments are described in more detail below.


Chemoradiation is a treatment that combines chemotherapy (cancer-killing medication) and radiotherapy (where radiation is used to kill cancer cells).

It’s currently the most effective treatment for anal cancer. You don’t usually need to stay in hospital when you’re having chemoradiation.

Chemotherapy for anal cancer is usually given in two cycles, each lasting four to five days, with a four-week gap between the cycles.

You typically undergo radiation therapy for anal cancer for five or six weeks. Chemotherapy is typically administered during the first week and the fifth week. Your doctor tailors your treatment schedule based on characteristics of your cancer and your overall health.

In many cases, part of the chemotherapy is delivered through a small tube called a peripherally inserted central catheter in your arm, which can stay in place until your treatment has finished.

The tube means you don’t need to stay in hospital during each of the cycles of chemotherapy. However, you’ll be attached to a small plastic pump, which you take home with you.

A few hospitals now offer tablet chemotherapy for anal cancer, which avoids the need for the pump and peripherally inserted central catheter.

Though combining chemotherapy and radiation increases the effectiveness of the two treatments, it also makes side effects more likely. Discuss with your doctor what side effects to expect.

Both chemotherapy and radiotherapy often cause significant side effects, including:

  • tiredness
  • sore skin around the anus
  • sore skin around the penis and scrotum in men or vulva in women
  • hair loss – limited hair loss from the head, but total loss from the pubic area
  • feeling sick
  • diarrhea

These side effects are usually temporary, but there’s also a risk of longer-term problems, such as infertility.

If you’re concerned about the potential side effects of treatment, you should discuss this with your care team before treatment begins.

Other possible long-term side effects can include:

  • bowel control problems
  • long-term (chronic) diarrhea
  • erectile dysfunction
  • vaginal pain when having sex
  • dry and itchy skin around the groin and anus
  • bleeding from the anus, rectum, vagina or bladder

Tell your doctor if you develop any of these symptoms so they can be investigated and treated.


Surgery is a less common treatment option for anal cancer. It’s usually only considered if the tumor is small and can be easily removed, or if chemoradiation hasn’t worked.

If the tumor is very small and clearly defined, it may be cut out during a procedure called a local excision. This is a relatively simple procedure, carried out under general anesthetic, that usually only requires a stay in hospital of a few days.

  • Surgery to remove early-stage anal cancers. Very small anal cancers may be removed through surgery. During this procedure, the surgeon removes the tumor and a small amount of healthy tissue that surrounds it. Because the tumors are small, early-stage cancers can sometimes be removed without damaging the anal sphincter muscles that surround the anal canal. Anal sphincter muscles control bowel movements, so doctors work to keep the muscles intact. Depending on your cancer, your doctor may also recommend chemotherapy and radiation after surgery.
  • Surgery for late-stage anal cancers or anal cancers that haven’t responded to other treatments. If your cancer hasn’t responded to chemotherapy and radiation (chemoradiation) or if your cancer is advanced, your doctor may recommend a more complex operation called abdominoperineal resection, which is sometimes referred to as an AP resection. An abdominoperineal resection involves removing your anus, rectum, part of the colon, some surrounding muscle tissue, and sometimes some of the surrounding lymph nodes (small glands that form part of the immune system) to reduce the risk of the cancer returning. The surgeon then attaches the remaining portion of your colon to an opening (stoma) in your abdomen through which your stools will leave your body and collect in a colostomy bag.  You’ll usually need to stay in hospital for up to 10 days after this type of surgery. Before and after the operation, you’ll see a specialist nurse who can offer support and advice to help you adapt to life with a colostomy.Adjusting to life with a colostomy can be challenging, but most people become accustomed to it over time.

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. Palliative care can be used while undergoing other aggressive treatments, such as surgery, chemotherapy or radiation therapy.

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 overwhelming and frightening. You can help yourself to feel more in control by taking an active role in your health care. To help you cope, try to:

  • Learn enough about anal cancer to make decisions about your care. Ask your doctor about your anal cancer, including the stage of your cancer, your treatment options and, if you like, your prognosis. As you learn more about anal cancer, you may become more confident in making treatment decisions.
  • Keep friends and family close. Keeping your close relationships strong will help you deal with your anal 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 with whom you can 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.