Anal cancer is a growth of cells that starts in the anal canal. The anal canal is a short tube at the end of the rectum. Anal cancer may appear like a firm lump or bump, an open sore or ulcer, or a thickened, wartlike area of skin.

For most people, anal cancer develops after a long-term infection with a high-risk type of human papillomavirus (HPV) in the anal area.

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 that constantly bleeds, itches, or hurts. These symptoms might be mistaken for hemorrhoids. It is important to have a healthcare professional check the area and take a tissue sample, called a biopsy, from any growth to make a diagnosis.

Anal cancer is fairly rare, with about 0.2% of people developing it during their lifetime. Anal cancer is usually treated by a team of cancer specialists. Treatment of anal cancer has evolved over time. Today, anal cancer treatment options include chemotherapy, radiation therapy and surgery in some cases.

Types of anal cancer

The most common type of anal cancer is squamous cell carcinoma (SCC). It begins in the thin, flat squamous cells that line the anal canal and the ring of skin around the outside of the anus. Most cases are linked to human papillomavirus (HPV) infection, especially high-risk HPV types 16 and 18. A common treatment for SCC that has not spread includes concurrent chemotherapy and radiation.

Other types of anal cancer include:

• Adenocarcinoma. This uncommon type starts in the anal glands that produce mucus. Adenocarcinoma behaves like rectal cancer and is usually treated with surgery plus radiation and chemotherapy.
• Neuroendocrine carcinoma. This rare and highly aggressive cancer develops from neuroendocrine cells found in the anal canal. It can appear as either a small cell or large cell type. Both types tend to grow and spread quickly. This rare cancer is often treated with chemotherapy, radiation and sometimes surgery, depending on the size of the tumor.
• Basal cell carcinoma. This very rare cancer arises from the basal cells of the skin around the anus, known as the perianal region. Most people can be successfully treated with local surgical removal.
• Melanoma. This rare form of anal cancer is aggressive and develops from the pigment-producing cells in the anal or perianal skin, called melanocytes. Treatment often includes surgery and immunotherapy.

Anal cancer may begin without any noticeable symptoms. If symptoms appear, they may include:

• Bleeding from the anus or rectum.
• Blood in the stool.
• Pain in the area of the anus.
• A growth in the anal canal.
• Anal itching.
• Changes in stool appearance and bowel habits, including thinner stools or constipation.
• Having a feeling of fullness or needing to go to the bathroom, even after going to the bathroom.

When to see a doctor

Make an appointment with a doctor or other healthcare professional if you have any symptoms that worry you or if they are not going away. Typically a healthcare professional looks for any hemorrhoids, lumps, tears called fissures, or lesions, that need to be tested.

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, 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 tell the cancer cells to make many more cells quickly. Cancer cells can keep living while healthy cells would die. This results in 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 caused by human papillomavirus (HPV). This 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.

Things that may increase the risk of anal cancer include:

• Being exposed to human papillomavirus (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, as this activity may be linked to a higher chance of getting high-risk HPV.
• Smoking cigarettes. People who smoke cigarettes have an increased risk of anal cancer.
• Having a history of certain cancers. Those who have had penile, 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 human immunodeficiency virus (HIV), also can weaken the immune system.
• Having a history of sexually transmitted disease (STD). Several types of STDs, including anal warts, may increase your risk of anal cancer.

It is not common for anal cancer to spread to distant parts of the body. When it does spread, it tends to travel to the liver and 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 STDs. This may include using a condom every time you have sex and limiting the number of sexual partners you have.
• Get the HPV vaccine. Getting 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.
• Have high-risk HPV.
• Are taking medicine to manage 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 finger, coated with a water-based jelly, 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.

Anal cancer often develops slowly over many years from HPV‑related precancerous changes. Tests and procedures used to diagnose anal cancer include:

Digital rectal exam. During a digital rectal exam, a healthcare professional inserts a gloved finger, coated with a water-based jelly, into the anus. The health professional feels the anal canal and rectum for growths or other signs of cancer.

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.

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.

Anal cancer treatment often starts with chemotherapy and radiation therapy. Sometimes surgery is used to remove 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 into 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

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

• Surgery for cancer that hasn't responded to other treatments. If the cancer remains after chemotherapy and radiation, your doctor may recommend abdominoperineal resection (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.

• Surgery for very small anal cancers. Though it's very uncommon, 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 type of anal cancer, chemotherapy and radiation after surgery also may be recommended.

Treatments for cancer that has spread

If anal cancer spreads to other parts of the body, other treatments might be used. Chemotherapy and immunotherapy medicines may be used at the same time or separately to treat advanced anal cancer.

• Chemotherapy. 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. There are several immunotherapy medicines used to treat anal cancer that spreads. Treatment usually starts with retifanlimab (Zynyz) combined with chemotherapy medicines.

Palliative care

Palliative care is a special type of care to help 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 perhaps live longer.

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

Speak with your healthcare team about:

Gentle exercise

If you get the OK from your healthcare team, start with gentle exercise. Add more exercise as you feel up to it. Consider walking, swimming, yoga and tai chi.

Managing stress

Try stress relief techniques such as muscle relaxation or visualization. Writing in a journal also may help.

Massage therapy

During a massage, a massage therapist applies pressure to your skin and muscles. Some massage therapists are specially trained to work with people who have cancer. Ask your healthcare team for names of massage therapists in your community.

Acupuncture

During an acupuncture session, a trained acupuncturist inserts thin needles into precise points on your body. Some acupuncturists are specially trained to work with people with cancer. Ask your healthcare team to recommend an acupuncturist at Mayo Clinic or within your community.

People facing a serious illness often say they feel worried about the future. With time, these strategies may help you find comfort:

• 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 it easier to make decisions about your care.

• Stay connected to friends and family. Keeping in touch with friends and family may give comfort during a time that is difficult for everyone.

  Your friends and family will likely ask if there's anything they can do to help you, so 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 must 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.

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 limit what you eat.
• 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 given during an appointment. Someone who comes with 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 there isn't enough time. 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?

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. Treatment options depend on the type of anal cancer. They also depend on whether the cancer remains local to the anal canal or has spread to other organs.

Stage 1 anal cancer

In stage 1, the cancer is small and still confined to the anal area. There are no lymph nodes involved.

Stage 2 anal cancer

In stage 2, the cancer is larger and still mainly in the anal area. There is no or limited lymph node involvement.

Stage 3 anal cancer

In stage 3, the cancer has advanced and may have spread to lymph nodes or traveled to local organs, including the vagina, urethra or bladder.

Stage 4 anal cancer

In stage 4, the cancer has traveled to distant organs.

If anal cancer is caught while it is still small and has not spread, most people can be successfully treated and live many years, often with their usual control of their bowel movements. As the cancer grows deeper into the anal wall or spreads to other parts of the body, the chance of a cure becomes lower.

Survival statistics

To understand survival rates, experts study many people being treated for anal cancer and then report how many are living five years after their diagnosis.

Many people expect the anal cancer survival rates to be reported by numbered stages, from 1 to 4. But the U.S. National Cancer Institute (NCI) reports survival rates by how far the cancer has spread. This is called summary staging, and the categories include localized, regional and distant anal cancer.

Stage	5-year survival rate
Localized: Cancer is only in the anal area.	85%
Regional: Cancer has spread to nearby tissues or lymph nodes.	70%
Distant: Cancer has spread to distant organs, such as the liver or lungs.	36%