Anal cancer


Anal cancer is a growth of cells that starts in the anal canal. The anal canal is a short tube at the end of rectum. Stool passes through the anal canal as it leaves the body.

Anal cancer can cause symptoms such as rectal bleeding, blood in the stool and anal pain. As it grows, it might cause a growth or lump. Sometimes these symptoms might be mistaken for hemorrhoids.

In the past, most people with anal cancer had surgery to remove the cancer. Often this operation involved making a new way for waste to leave the body. Today, most anal cancer treatment involves chemotherapy and radiation therapy. With this approach, surgery might not be needed.

Anal canal


Anal cancer signs and symptoms include:

  • Bleeding from the anus or rectum.
  • Blood in the stool.
  • Pain in the area of the anus.
  • A mass or growth in the anal canal.
  • Anal itching.
  • Having to go to the bathroom more often.

When to see a doctor

Make an appointment with a doctor or other healthcare professional if you have any symptoms that worry you.


Anal cancer happens when cells in the anal canal develop changes in their DNA. A cell's DNA holds the instructions that tell a cell what to do. In healthy cells, the DNA gives instructions to grow and multiply at a set rate. The instructions tell the cells to die at a set time. In cancer cells, the changes give different instructions. The changes tell the cancer cells to make many more cells quickly. Cancer cells can keep living when healthy cells would die. This causes too many cells.

The cancer cells might form a mass called a tumor. The tumor can grow to invade and destroy healthy body tissue. In time, cancer cells can break away and spread to other parts of the body. When cancer spreads, it's called metastatic cancer.

Most anal cancers are thought to be caused by human papillomavirus, also called HPV. HPV is a common virus that's passed through sexual contact. For most people, the virus never causes problems. It usually goes away on its own. For some, though, the virus can cause changes in the cells that may lead to cancer.

Risk factors

Things that may increase the risk of anal cancer include:

  • Being exposed to human papillomavirus, also called HPV. HPV is a common virus that's passed through sexual contact. For most people, it causes no problems and goes away on its own. For others, it causes changes in the cells that can lead to many types of cancer, including anal cancer.
  • Increasing number of sexual partners. The greater your number of sexual partners, and the greater your partner's number of sexual partners, the greater your chance of acquiring HPV.
  • Having anal sex. People who have receptive anal sex have an increased risk of anal cancer.
  • Smoking cigarettes. People who smoke cigarettes have an increased risk of anal cancer.
  • Having a history of cancer. Those who have had cervical, vulvar or vaginal cancer have an increased risk of anal cancer.
  • Having a weak immune system. If the body's germ-fighting immune system is weakened by medicines or illness, there might be a higher risk of anal cancer. People with a weakened immune system include those taking medicines to control the immune system, such as after an organ transplant. Certain medical conditions, such as infection with HIV, also can weaken the immune system.


Anal cancer rarely spreads to other parts of the body. Only a small percentage of cancers are found to have spread. Those that do are especially difficult to treat. Anal cancer that spreads most commonly goes to the liver and the lungs.


Take steps to reduce your risk

There is no sure way to prevent anal cancer. To reduce your risk of anal cancer:

  • Practice safer sex. Reduce your risk of anal cancer by taking measures to prevent sexually transmitted infections. This may include using a condom every time you have sex and limiting the number of sexual partners you have.
  • Consider the HPV vaccine. Receiving a vaccination to prevent HPV infection may reduce your risk of anal cancer and other HPV-related cancers. Ask your healthcare team if an HPV vaccine is right for you.
  • Don't use tobacco. If you don't use tobacco, don't start. If you currently use tobacco of any kind, talk with a healthcare professional about strategies to help you quit.

Ask about anal cancer screening

Screening tests can help detect anal cancer and precancerous cells that may one day develop into anal cancer. Healthcare professionals sometimes recommend screening for people with a high risk of anal cancer.

You might have a high risk of anal cancer if you:

  • Have HIV.
  • Are taking medicine to control your immune system after an organ transplant.
  • Have been diagnosed with precancerous cells in the penis, scrotum, cervix, vagina or vulva.

Screening tests might include:

  • Anal Pap test. During an anal Pap test, a healthcare professional swabs cells from your anal canal. The cells are tested in a lab to check for cancer cells and cells that look like they could become cancerous.
  • Anal HPV test. The anal HPV test involves testing cells from the anal canal for infection with HPV.
  • Digital rectal exam. During a digital rectal exam, a healthcare professional inserts a gloved, lubricated finger into the anus. The health professional feels the anal canal and rectum for growths or other signs of cancer.

Medical groups don't agree on who should have anal cancer screening and what tests should be used. Screening can detect anal cancer when it's small and easier to treat. But studies haven't proved that anal cancer screening can save lives. Talk about the benefits and risks of screening with your healthcare team.


Tests and procedures used to diagnose anal cancer include:

Examining the anal canal and rectum

During a digital rectal exam, a healthcare professional inserts a gloved, lubricated finger into your anus. The health professional feels the anal canal and rectum for growths or other signs of cancer.

Using a scope to examine the anal canal, called an anoscopy

During an anoscopy, a healthcare professional inserts a thin, flexible tube with a light through the anal canal and rectum. This tube is called an anoscope. A lens on the anoscope allows a healthcare professional to examine the inside of the anal canal.

Imaging tests

Imaging tests make pictures of the body. They can show the location and size of the cancer. Tests might include ultrasound, X-ray, MRI, CT scan and positron emission tomography scan, which also is called a PET scan.

Removing a sample of tissue for testing, also called biopsy

A biopsy is a procedure to remove a sample of tissue for testing in a lab. The sample is often collected during an anoscopy. Special tools can go through the anoscope to collect the cells. The sample is tested in a lab to see if it is cancer. Other special tests give more details about the cancer cells. Your healthcare team uses this information to make a treatment plan.


If you're diagnosed with anal cancer, you may have other tests to see if the cancer has spread. These tests help your healthcare team find out the extent of your cancer, also called the stage. Cancer staging tests often involve imaging tests. The tests might look for signs of cancer in your lymph nodes or in other parts of your body. Your healthcare team uses the results of your cancer staging tests to help create your treatment plan.

The stages of anal cancer range from 1 to 4. The lowest number means that the cancer is small and only in the anal canal. A higher stage means the cancer is more advanced. A stage 4 anal cancer has spread to other areas of the body.


Anal cancer treatment often starts with chemotherapy and radiation therapy. Sometimes surgery is used to remove the cancer. When the cancer spreads to other parts of the body, different treatments might be used. These might include chemotherapy on its own and immunotherapy. The treatment that's best for you depends on several factors. These include the stage of your cancer, your overall health and your own preferences.

Combined chemotherapy and radiation

Anal cancer is usually treated with a combination of chemotherapy and radiation. Together, these two treatments enhance each other to kill cancer cells.

  • Chemotherapy. Chemotherapy treats cancer with strong medicines. Treatment often involves a combination of chemotherapy medicines. Some are injected in a vein and others come in pill form.
  • Radiation therapy. Radiation therapy treats cancer with powerful energy beams. The energy can come from X-rays, protons or other sources. During radiation therapy, a machine directs beams of energy to specific points on the body to kill the cancer cells there.

Radiation is typically given daily over several weeks. How often you receive chemotherapy treatments over those weeks will depend on what medicines your healthcare team chooses. Your care team tailors your treatment schedule based on characteristics of your cancer and your overall health.


Surgery might be used to treat anal cancer in certain situations. Operations might include:

  • Surgery for very small anal cancers. Though it's not common, some very small anal cancers are treated with surgery alone. The surgeon removes the cancer and some of the healthy tissue around it. This ensures that all the cancer cells are removed.

    This might be an option only if the cancer is very small and the surgery won't hurt the muscles that surround the anal canal. These muscles, called anal sphincter muscles, control bowel movements.

    Depending on your cancer, chemotherapy and radiation after surgery also may be recommended.

  • Surgery for cancer that hasn't responded to other treatments. If the cancer remains after chemotherapy and radiation, your doctor may recommend abdominoperineal resection, also called APR. During APR the surgeon removes the anal canal, rectum and part of the colon. The surgeon then attaches the remaining part of your colon to an opening in your abdomen called a stoma. Waste leaves the body through the stoma and collects in a colostomy bag.

Treatments for cancer that has spread

If anal cancer spreads to other parts of the body, other treatments might be used. These might include:

  • Chemotherapy alone. Chemotherapy medicines can control the growth of cancer cells throughout the body.
  • Immunotherapy. Immunotherapy is a treatment with medicine that helps the immune system kill cancer cells. The immune system fights off diseases by attacking germs and other cells that shouldn't be in the body, such as cancer cells. Cancer cells survive by hiding from the immune system. Immunotherapy helps the immune system cells find and kill the cancer cells. It might be used in certain situations.

Palliative care

Palliative care is a special type of healthcare that helps you feel better when you have a serious illness. If you have cancer, palliative care can help relieve pain and other symptoms. A team that may include doctors, nurses and other specially trained health professionals provides palliative care. The team's goal is to improve quality of life for you and your family.

Palliative care specialists work with you, your family and your care team. They provide an extra layer of support while you have cancer treatment. You can have palliative care at the same time you're getting strong cancer treatments, such as surgery, chemotherapy or radiation therapy.

The use of palliative care with all the other appropriate treatments can help people with cancer feel better and live longer.

Alternative medicine

Alternative medicine treatments won't kill cancer cells. But some alternative medicine treatments may help you cope with the side effects of cancer treatment. Your healthcare team can treat many side effects, but sometimes medicines aren't enough. Alternative treatments may offer additional comfort.

Options for common side effects include the following:

  • Anxiety — massage, meditation, hypnosis, music therapy, exercise or relaxation techniques.
  • Fatigue — gentle exercise or tai chi.
  • Nausea — acupuncture, hypnosis or music therapy.
  • Pain — acupuncture, massage, music therapy or hypnosis.
  • Sleep problems — yoga or relaxation techniques.

While these options are generally safe, talk with your healthcare team first to be sure that alternative medicine options won't affect your cancer treatment.

Coping and support

People facing a serious illness often say they feel worried about the future. With time, you'll find ways to cope with your feelings, but you may find comfort in these strategies:

  • Ask questions about anal cancer. Write down questions you have about your cancer. Ask these questions at your next appointment. Also ask your healthcare team for reliable sources where you can get more information.

    Knowing more about your cancer and your treatment options may make you more comfortable when you make decisions about your care.

  • Stay connected to friends and family. Your cancer diagnosis can be stressful for friends and family too. Try to keep them involved in your life.

    Your friends and family will likely ask if there's anything they can do to help you. Think of tasks you might like help with. For example, you may ask a friend to be there for you when you want to talk. You may ask for help caring for your home if you have to stay in the hospital.

    You may find comfort in the support of a caring group of your friends and family.

  • Find someone to talk with. Find someone you can talk to who has experience helping people facing a life-threatening illness. Ask your healthcare team to suggest a counselor, clergy member or medical social worker you can talk with. For support groups, contact the American Cancer Society or ask your healthcare team about local or online groups.

Preparing for an appointment

Make an appointment with a doctor or other healthcare professional if you have any symptoms that worry you.

If your health professional thinks you have anal cancer, you may be referred to a specialist. Often this is a surgeon or doctor who treats digestive diseases, called a gastroenterologist. You also may be referred to a doctor who specializes in treating cancer, called an oncologist.

Because appointments can be brief, it's a good idea to be prepared. Here's some information to help you get ready.

What you can do

  • Be aware of any pre-appointment restrictions. At the time you make the appointment, be sure to ask if there's anything you need to do in advance. For example, you might need to restrict your diet.
  • Write down symptoms you're experiencing, including any that may not seem related to the reason for which you scheduled the appointment.
  • Write down key personal information, including major stresses or recent life changes.
  • Make a list of all medicines, vitamins or supplements you're taking and the doses.
  • Take a family member or friend along. Sometimes it can be difficult to remember all the information provided during an appointment. Someone who accompanies you may remember something that you missed or forgot.
  • Write down questions to ask your healthcare team.

Your time with your healthcare team is limited. Prepare by making a list of questions. List your questions from most important to least important in case time runs out. For anal cancer, some basic questions to ask include:

  • What is the stage of my cancer?
  • What other tests do I need?
  • What are my treatment options?
  • Is there one treatment that's best for my type and stage of cancer?
  • What are the potential side effects for each treatment?
  • Should I seek a second opinion? Can you give me names of specialists you recommend?
  • Am I eligible for clinical trials?
  • Are there brochures or other printed material that I can take with me? What websites do you recommend?
  • What will determine whether I should plan for a follow-up visit?

What to expect from your doctor

Be prepared to answer questions about your symptoms and your health, such as:

  • When did you begin experiencing symptoms?
  • Have your symptoms been continuous or occasional?
  • How severe are your symptoms?
  • What, if anything, seems to improve your symptoms?
  • What, if anything, appears to worsen your symptoms?

Content From Mayo Clinic Updated: 11/28/2023
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