The short answer
Anal cancer is an uncommon cancer of the anus, often linked to the human papillomavirus (HPV). Symptoms can include bleeding, a lump, or discomfort, which are far more often caused by common conditions like hemorrhoids. Many anal cancers are treated successfully with combined chemotherapy and radiation.
Anal cancer is uncommon and often linked to HPV.
Symptoms like bleeding or a lump are usually caused by benign conditions.
Any lasting anal bleeding, lump, or change should be checked.
Treatment is often chemotherapy combined with radiation, avoiding surgery for many.
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The full explanation.
What anal cancer is
Anal cancer starts in the anus, the short opening at the end of the digestive tract. It is uncommon, far less common than cancer of the colon or rectum. Nearly 9 in 10 anal cancers are squamous cell carcinoma. This type starts in the flat cells lining the anal canal and the skin just outside it.
The HPV connection
Most anal cancer is linked to human papillomavirus, or HPV. This is the same virus responsible for most cervical cancer. HPV infection is common. Most infections clear on their own without ever causing a problem. Risk rises for people with a weakened immune system. This includes people with HIV and people who have had an organ transplant. Men who have sex with men, and anyone with a history of receptive anal intercourse, also face higher risk. Smoking also raises risk. HPV vaccination lowers the risk of developing HPV-related anal cancer in the first place. That is part of why the vaccine is recommended well before most people become sexually active.
Symptoms
The most common first sign is bleeding from the anus or rectum. Other symptoms include:
- Pain or a feeling of fullness in the anal area.
- Itching in or around the anus.
- A lump or mass at the anal opening.
- Unusual discharge from the anus.
- Stools that are thinner than usual, or a change in bowel movements.
- Loss of bowel control, in more advanced cases.
- Swollen lymph nodes in the groin.
Every one of these symptoms is far more often caused by hemorrhoids. Other common, non-cancerous conditions cause them too. That overlap is exactly why new or persistent symptoms need a doctor's evaluation, not a guess. Do not assume bleeding is hemorrhoids without being checked, especially if it is new or does not resolve.
How it is treated
For most people, anal cancer is treated without removing the anus. The standard treatment combines radiation therapy with chemotherapy at the same time. Doctors call this chemoradiation. This usually runs five to seven weeks. Chemotherapy drugs are given during specific weeks of the radiation course. The most common combination is 5-fluorouracil or capecitabine, plus mitomycin. This approach aims to cure the cancer while preserving the anal sphincter. That is the muscle that controls bowel movements, and it matters enormously for quality of life afterward.
Doctors wait roughly six months after chemoradiation finishes to judge the full result. The tumor can keep shrinking well after treatment ends. If cancer remains after that period, further treatment is needed. This can include a more localized surgery. In some cases, a larger operation called an abdominoperineal resection is needed. It removes the anus and rectum and requires a permanent colostomy.
Anal cancer can spread to distant organs like the liver or lungs. When that happens, cure becomes unlikely. Treatment shifts to chemotherapy, sometimes combined with immunotherapy. The goal becomes controlling the cancer and easing symptoms for as long as possible.
What to ask your team
- Is chemoradiation an option for me, and what does the schedule involve?
- How will you assess whether the cancer is gone after treatment?
- What can be done to manage side effects like skin irritation or bowel changes during treatment?
- If cancer remains after chemoradiation, what happens next?
Sources
Words to know
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Common questions
What causes anal cancer?
Many anal cancers are linked to long-term infection with certain types of HPV. Smoking and a weakened immune system also raise risk.
What are the symptoms?
Bleeding, a lump near the anus, itching, pain, or a change in bowel habits — though these are far more often caused by hemorrhoids or other benign conditions.
Is anal cancer treatable?
Yes. Many anal cancers respond well to combined chemotherapy and radiation, which can avoid major surgery for many people.
Can HPV vaccination help?
HPV vaccination lowers the risk of HPV-related cancers, including anal cancer, when given before exposure to the virus.
Questions to ask your doctor
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Sources last checked: 2026-07-21 what this meansLast updated: 2026-08-05Next planned review: 2027-07-21
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How this page was created
Cancer Explained does not originate medical claims. Every page restates guidance already published by the National Cancer Institute, the CDC, the USPSTF and the FDA, in plain language, with the source cited so you can check the original yourself. AI does the translating and organizing; automated checks test claims, citations, clarity and safety before anything publishes. We do not employ clinicians and do not intend to — our work is translation and navigation, not clinical judgment. Nothing here is personal medical advice, and no page can account for your particular situation.
Editorial status: Editorial review complete — This page completed Cancer Explained's editorial checks (sources, safety, plain language, duplication). It has not been reviewed by a physician or other healthcare professional.
Human medical review: not completed. Pages here are not signed off by a clinician before they publish. That is not an oversight we are quietly working around: we restate published guidance and cite it, so the authority belongs to the source rather than to us, and every page names where its claims come from — you can verify us instead of trusting us. Where a volunteer clinician has reviewed a page, their name and credentials appear on it; where no name appears, no clinician has checked it. We are glad to have reviewers and are recruiting them, and we do not hold pages back waiting for one. Use this site to understand your situation and to ask better questions of the people treating you.
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