Anal Cancer
Medically reviewed by: Rachel Klein, MSN, CRNP
Last Updated: 2026
Anal cancer starts in the tissues of the anus, the opening at the end of the large intestine where stool (poop) leaves the body. The most common type of anal cancer is squamous cell carcinoma. This type makes up 9 out of 10 cases. It starts in the thin, flat cells that line the anal canal. The anal canal connects the anus to the rectum. It is about 1 ½ to 2 inches long. Squamous cell carcinoma can also grow in the perianal skin, or the skin around the anus.
Infection with human papilloma virus (HPV) is the main cause of anal cancer. HPV is the name for a group of more than 200 related viruses. Those that cause cancer are called “high risk” HPVs. The HPV vaccine can help prevent infections from HPVs that cause cancer.
Less common types of anal cancer include:
- adenocarcinoma
- basal cell carcinoma
- melanoma
- gastrointestinal stromal tumor
- lymphoma
Anal cancer is not the same as colorectal cancer, even though they both happen in the digestive system. Colorectal cancer starts in the colon or rectum, which are parts of the large intestine. Anal cancer starts in the anus or the skin around it. Even though these areas are close together, the cancers develop from different types of cells and are treated in different ways. Understanding the difference can help you get the right information and support for your situation.
Anal cancer is rare, but cases have been rising over the past several decades. In the U.S., about 11,000 people are diagnosed with anal cancer each year.
The good news: when found early, anal cancer is often treatable, and many people do well after treatment.
Risk Factors
Certain medical conditions, genetic factors, or lifestyle may act together to increase the risk of anal cancer. Having these risk factors does not mean you will get cancer, but they may increase chances of cancer cells developing:
- HPV (human papilloma virus) infection – HPV is a very common virus spread mainly through intimate skin to skin contact, including vaginal, anal, and oral sex. The highest‑risk strains for cancer development are HPV‑16 and HPV‑18. Getting the HPV vaccine greatly decreases the risk of HPV-related cancers.
- Weakened immune system – Such as from HIV infection or medicines after an organ transplant
- History of HPV‑related cancers or conditions – Such as cervical, vaginal, or vulvar cancer, or anal warts
- High‑risk sexual behaviors – Including receiving anal sex and having many sexual partners
- Smoking cigarettes
- Age – Risk increases as people get older
- Sex and race/ethnicity – Anal cancer is more common in White women and Black men
Signs and Symptoms
Many anal cancers can be found early. Talk with your healthcare team if you notice:
- Bleeding from the anus or rectum – seeing blood on the toilet paper, in the toilet bowl, or mixed with your stool (poop)
- Pain, pressure, or a lump near the anus
- Itching or discharge
- Changes in bowel habits (constipation, cramping with bowel movements, narrowing stool, feeling of fullness, or feeling the urge to poop all the time)
- Blood in urine, painful intercourse, or difficulty urinating
- Severe fatigue, breathlessness, lightheadedness (signs of anemia or blood loss)
- Unexplained weight loss
Other non-cancer conditions — such as hemorrhoids, constipation, irritable bowel syndrome, or even pregnancy — can cause similar symptoms. Hemorrhoids are swollen or irritated blood vessels in the lining of the anus or rectum. It’s important to get checked if you notice any of these symptoms, even if they seem minor. You may feel embarrassed or nervous about bringing up these symptoms, but it’s important to speak up and to advocate for answers and exams. Your care team is used to having these conversations.
Screening
There is no routine screening recommended for the general public. But people at higher risk or those having symptoms may undergo screening tests. These may include:
- Anal Pap test (anal cytology) – The anal lining is swabbed with a soft brush and the cells are examined in a lab.
- Digital rectal exam (DRE) – The doctor inserts a gloved, lubricated finger into the anus to feel for lumps or other changes.
- Anoscopy – The doctor gently inserts a short, hollow, firm tube into the anus and uses a light to see the lining of the anus and rectum.
Note: A colonoscopy screens for colorectal cancer, not anal cancer. Anal cancer would not likely be detected during a colonoscopy.
Ask your doctor if screening makes sense for you. Share any symptoms you are having, and advocate for yourself to make sure your concerns are addressed.
Diagnosis & Staging
Diagnosis
If symptoms or a screening test suggests a problem, your doctor may use one or more of the following tests to make a diagnosis:
- Anoscopy – The doctor gently inserts a short, hollow, firm tube into the anus and uses a light to see the lining of the anus and rectum.
- Sigmoidoscopy or colonoscopy – These tests look at nearby parts of the colon and rectum to see if there are any other areas of concern.
- Biopsy – A tissue sample is removed and examined under a microscope for abnormal cells.
- Imaging – Imaging tests can help see if the cancer has spread. These may include:
- Ultrasound – uses sound waves to create images of the inside of your body
- CT (computed tomography) scan – uses x-rays to make detailed cross-sectional images of your body
- MRI (magnetic resonance imaging) – uses radio waves and strong magnets to show details inside your body
- PET (positron emission tomography) – uses a sugar substance and special camera to see if and where cancer has spread
Staging
If anal cancer is diagnosed, the doctor needs to know the stage, or extent, of the disease to plan the best treatment. Staging is used to find out whether the cancer has spread, and if so, to which parts of the body. The following stages are used for anal cancer:
- Stage I – The cancer is found in the anal canal beneath the top layer of cells. Cancer cells are found only in the anus.
- Stage II – The tumor is between 2–5 cm and may have spread to nearby lymph nodes, but not distant parts of the body.
- Stage III – The tumor is larger than 5cm and may be growing into nearby organs (vagina, urethra, bladder).
- Stage IV – The cancer has spread to distant organs, like the liver or lungs.
Treatments & Side Effect Management
Treatment Options
Treatment options for anal cancer will depend on:
- The stage of your cancer
- Tumor type
- Your overall health (including HIV status or immunosuppression)
- Your treatment goals
As you are making treatment decisions, think about what is important to you and any personal goals you may have. Talk with your care team about your needs and preferences. Make sure you understand why one treatment might work better for you than another.
Consider getting a second opinion, when possible. Getting a second opinion will allow you to talk through options with your doctors. This can help to develop a treatment plan that best fits your needs.
The following are treatments for anal cancer:
- Chemoradiation
- Immunotherapy
- Radiation Therapy
- Targeted Therapy
- Surgery
- Clinical Trials
- Supportive Care
The standard treatment for local or regional anal cancer includes chemoradiation. This is called the Nigro protocol. It is a combination of:
- External beam radiation therapy (EBRT) – The use of high-energy rays to kill or damage cancer cells. External radiation is delivered from a large machine aimed at the anal area.
- Chemotherapy – The use of drugs to destroy or damage cancer cells. It is used to shrink tumors, slow cancer’s growth, relieve symptoms, or help people live longer.
This treatment may help avoid (or limit) surgery and helps you keep control of your bowel movements. Many people with localized anal cancer are cured with chemoradiation.
Ask your doctor about using a vaginal or rectal dilator during and after chemoradiation to help reduce side effects.
Immunotherapy uses the body’s natural defenses (the immune system) to find, attack, and kill cancer cells. It may be combined with chemotherapy to treat anal cancer.
Radiation therapy is the use of high-energy rays to kill or damage cancer cells. Radiation may be used for advanced anal cancer — to treat cancer that has spread to the bones, distant lymph nodes, brain, or spinal cord. Radiation can help control symptoms, like pain or bleeding.
Targeted therapy uses drugs to target specific changes in cancer cells that help them grow, divide, and spread. Targeted therapy drugs are designed to be more precise. They fight cancer cells while causing less harm to other cells in the body. There are different types of targeted therapies to treat anal cancer.
Most anal cancers are in the anal canal and are treated with chemotherapy and radiation. Surgery may be used with very early tumors or if the cancer comes back or doesn’t go away.
Perianal cancer (in the skin around the anus) is more likely to be treated with surgery.
Many people with anal cancer will also require a colostomy. A colostomy is a surgery to re-route the bowel away from the tumor (to an opening in the belly) so stool can pass easily. This can be temporary or permanent, depending on the extent of disease.
Be sure to ask about clinical trials. These are research studies to test new treatments or learn how to use current treatments better. In some cases, the treatments with the best chance of success may be available only through clinical trials. Trials are offered for many cancers, at many different stages. Everyone is not eligible for every trial. If you have cancer that has come back or spread, it is especially important to ask about clinical trials.
Maintaining your best possible quality of life is an important goal. Some care you receive may not treat your cancer. Instead, it will address possible symptoms caused by your cancer or side effects from treatment, such as nutrition needs or pain. It may help you with social, emotional, or spiritual concerns. This kind of care is called palliative care or supportive care.
Many hospitals offer palliative care at the same time as cancer treatment. Palliative care is not hospice. It is often provided by a palliative care specialist. This person is a doctor or nurse who focuses on symptoms, side effects, and emotional needs of patients. If you are not referred to a palliative care specialist soon after you learn you have anal cancer, ask to see one.
Follow-up care after treatment for anal cancer is important. You will need regular check-ups to monitor changes in your health. Check-ups may include physical exams and anoscopy. Talk to a doctor right away if you have any symptoms or concerns.
Side Effects
It helps to learn more about the side effects from your treatment(s) before you begin, so you will know what to expect. When you know more, you can work with your care team to manage your quality of life during and after treatment.
There are effective and readily available medications to help with traditional side effects from cancer treatment. Possible side effects for anal cancer include:
- Skin changes in the treated area (redness, soreness, peeling, irritation)
- Fatigue (feeling very tired) or weakness
- Bowel changes (diarrhea, constipation, urgency)
- Bladder irritation
- Nausea
- Lower blood counts (from chemotherapy), which can raise infection risk
- For people living with HIV or other immunosuppression, your treatment choices may differ. Ask your care team about benefits and risks of different options.
- Mouth sores
- Pain
- Sexual health changes (vaginal dryness or stenosis – narrowing or shortening of the vaginal canal; difficulty with erections; penis shrinkage)
- Fertility (the ability to have children)
- Talk to your care team about options for sperm banking or freezing your eggs.
Keep in mind that everyone reacts differently to treatment and experiences different side effects. There are support resources and coping strategies that can help.
Coping With Anal Cancer
An important step in managing your cancer and its treatment is to be informed.
Anal cancer may affect different areas of your life. If you are experiencing any challenges in these areas, there are resources to help:
- Navigating Mental Health and Cancer
- Coping With Stigma
- Intimacy, Sex, and Fertility
- Addressing Cancer Treatment Side Effects
- Managing the Cost of Cancer Treatment
- Support for Caregivers
- Long-Term Survivorship
A cancer diagnosis can bring many feelings — fear, anger, sadness, or worry. These are normal. Support can help you feel more in control. Consider:
- Support groups (in person or online)
- Counseling with an oncology social worker
- Peer mentors (one‑on‑one connections with someone who has been through anal cancer)
- Stress‑reduction (mindfulness, gentle exercise, breathing techniques)
Stigma is the negative feeling people have towards a situation or condition. People can feel stigmatized when they feel judged related to a behavior or trait.
Anyone can get anal cancer. Anal cancer happens when cells in the anus mutate or change. Due to the link between HPV infections and anal cancer, some people with anal cancer may experience stigma in the form of judgement, guilt, or shame.
Sometimes, side effects from cancer treatments and the stress of having cancer can lead to sexuality, intimacy, and fertility issues. There are steps you can take to address both intimacy and fertility concerns.
Receiving a cancer diagnosis and undergoing cancer treatment can be challenging for both you and your loved ones. Unwanted side effects can intensify the disruption in your life even further.
Worries about costs of care are common when you are facing a cancer diagnosis. Learn how to talk about the financial side of cancer and where to go for help.
The ripples of a cancer diagnosis extend to spouses, partners, siblings, children, and friends. Many of these family members will find they now need to take on the role of caregiver — something they may never have done before.
The period after treatment may involve physical, emotional, and lifestyle adjustments. You may be adapting to a “new normal.” Survivorship requires many things — physical activity, nutrition, a healthy emotional life, and management of any health concerns that may arise.
Tips for Talking With Your Care Team
Bring these questions to your appointments:
- What type and stage of anal cancer do I have? Ask your doctor to explain the size, lymph nodes, and whether it has spread.
- What are my treatment options? Ask about the pros and cons of each option.
- What side effects should I expect, and how can I manage them?
- How will treatment affect my bowel control or bathroom habits?
- Will I need a colostomy? A colostomy is a small opening in the belly connected to a small bag worn outside the body to collect poop. Most people do not need one, but it may be needed in some situations.
- How long will treatment last, and how often are visits? Ask about the schedule and timing.
- Can I join a clinical trial?
- What support services are available for me and my caregivers? Consider support for nutrition, social work, mental health, sexual health, and financial counseling.
Keep Loved Ones Informed & Involved
Create your own private website to receive social, emotional, and practical support from friends and family during your treatment and beyond.
Getting the Support You Want and Need
Cancer brings up many feelings. It affects you, your family, and your loved ones. It is normal to feel sad, anxious, worried, shocked, stressed, or panicked. Remember that cancer can impact anyone, and every person deserves good care and support.
Keep in mind the following:
- Be open to asking your care team questions. Keep asking questions if there is something you do not understand. If you are a visual learner, ask if they can provide an image or drawing to help explain.
- Know what signs or symptoms you should tell your care team about right away.
- Focus on what you can control. Take things one small step at a time. Do not try to make changes right away.
- Be gentle with yourself when you are feeling stressed. You may feel more anxious when it gets close to a doctor’s appointment. It may help to take someone with you to be an extra set of eyes or ears during the visit.
- Share your feelings with trusted friends, family members, a case manager or counselor, or a clergyperson or spiritual advisor.
- Ask for help from friends and your community through CSC’s MyLifeLine — a free service offered by the Cancer Support Community.