Anal Cancer: Symptoms, Causes, Treatment & Complete Guide
Updated: 3 days ago
Medically reviewed by Dr. Baraa Alnahhal, MD · Last reviewed: October 17, 2026
Anal cancer is a growth of cells that starts in the anal canal, usually after a long-term infection with high-risk HPV. Its symptoms are often mistaken for hemorrhoids, which is why any persistent bleeding, pain, or lump deserves a professional check.
Quick Answer
Anal cancer is a growth of cells that starts in the anal canal at the end of the rectum, usually after a long-term infection with a high-risk type of human papillomavirus (HPV) [1]. Symptoms such as rectal bleeding, anal pain, a growth or itching are often mistaken for hemorrhoids. It is usually treated with combined chemotherapy and radiation [2].
What the research says
HPV is behind most cases. A 2026 imaging review notes HPV is implicated in nearly 90% of anal squamous cell carcinoma, a cancer that is vaccine-preventable (Young et al., Magnetic Resonance Imaging Clinics of North America, 2026) [3].
Stage matters when choosing treatment. In a Japanese multicenter retrospective study, overall survival after chemoradiotherapy and surgery was similar for stages I–II (adjusted HR 0.89; 95% CI, 0.48–1.63), but surgery was linked to lower survival in stage III (adjusted HR 1.82; 95% CI, 1.06–3.11) (Shimoike et al., International Journal of Clinical Oncology, 2026) [4].
Self-collected screening swabs look promising. In a pilot of 50 HIV-positive patients, self-collected anal samples detected high-risk HPV with 87.5% sensitivity and 81.8% specificity compared with physician-collected samples (Miyazaki et al., Diseases of the Colon & Rectum, 2026) [5].
Anal Cancer at a Glance
Aspect | Summary |
What it is | Cancer that starts in the anal canal (1½ inches long, at the end of the rectum) [1] |
How common | Fairly rare — about 0.2% of people develop it during their lifetime [1] |
Main cause | Long-term infection with high-risk HPV (especially types 16 and 18) [1] |
Most common type | Squamous cell carcinoma (SCC) |
Signature symptoms | Rectal bleeding, anal pain, lump/growth, itching — often mistaken for hemorrhoids [1] |
Main treatment | Combined chemotherapy + radiation (they enhance each other) [2] |
If it spreads | |
Care team | Team of cancer specialists; sometimes a gastroenterologist, surgeon, or oncologist |
What Is Anal Cancer?
Anal cancer is a growth of cells that starts in the anal canal, a short tube at the end of the rectum measuring about 1½ inches (4 centimeters) [1]. Muscles called sphincters surround the canal and relax to allow waste to leave the body [1]. Anal cancer may appear as:
A firm lump or bump
An open sore or ulcer
A thickened, wartlike area of skin [1]
For most people, it develops after a long-term infection with a high-risk type of HPV in the anal area [1]. It is usually treated by a team of cancer specialists, and it often develops slowly over many years from HPV-related precancerous changes [2].
What are the five types of anal cancer?
Type | Frequency | Where it starts | Key facts and typical treatment |
Squamous cell carcinoma (SCC) | Most common | Thin, flat squamous cells lining the anal canal and the ring of skin around the outside of the anus | Most cases linked to HPV, especially high-risk types 16 and 18; SCC that has not spread is commonly treated with concurrent chemotherapy and radiation [1] |
Adenocarcinoma | Uncommon | The anal glands that produce mucus | Behaves like rectal cancer; usually treated with surgery plus radiation and chemotherapy [1] |
Neuroendocrine carcinoma | Rare, highly aggressive | Neuroendocrine cells in the anal canal | Appears as small cell or large cell type; both tend to grow and spread quickly; often treated with chemotherapy, radiation, and sometimes surgery [1] |
Basal cell carcinoma | Very rare | Basal cells of the skin around the anus (perianal region) | Most people can be successfully treated with local surgical removal [1] |
Melanoma | Rare, aggressive | Pigment-producing cells (melanocytes) in the anal or perianal skin | Treatment often includes surgery and immunotherapy [1] |
What are the symptoms of anal cancer?
Anal cancer may begin without any noticeable symptoms, and later signs such as bleeding or anal pain can be mistaken for hemorrhoids [1]. If symptoms appear, they may include:
The Hemorrhoid Trap
As anal cancer grows, it might cause a growth or lump that constantly bleeds, itches, or hurts — symptoms that might be mistaken for hemorrhoids. This is why it is important to have a healthcare professional check the area and take a tissue sample (a biopsy) from any growth to make a diagnosis [1].
When to See a Doctor
Make an appointment with a doctor or other healthcare professional if you have any symptoms that worry you or that are not going away. Typically, a healthcare professional looks for any hemorrhoids, lumps, tears called fissures, or lesions that need to be tested [1].
What causes anal cancer?
Anal cancer happens when cells in the anal canal develop changes in their DNA [1]. In healthy cells, DNA gives instructions to grow and multiply at a set rate and to die at a set time. In cancer cells, the changes tell them to make many more cells quickly and to keep living while healthy cells would die. The cancer cells might form a mass called a tumor, which can grow to invade and destroy healthy tissue; in time, cells can break away and spread to other parts of the body — called metastatic cancer [1].
Most anal cancers are caused by human papillomavirus (HPV), a common virus passed through sexual contact. For most people, the virus never causes problems and usually goes away on its own [1]. For some, though, it can cause changes in the cells that may lead to cancer.
What are the risk factors for anal cancer?
Risk factor | Why it matters |
HPV exposure | A common virus passed through sexual contact; for some, it causes cell changes that can lead to anal cancer and other cancers |
Increasing number of sexual partners | The greater your number of partners — and your partners' number of partners — the greater the chance of acquiring HPV [1] |
Receptive anal sex | Linked to a higher chance of getting high-risk HPV, increasing anal cancer risk [1] |
Smoking cigarettes | Smokers have an increased risk of anal cancer [1] |
History of certain cancers | Prior penile, cervical, vulvar, or vaginal cancer increases risk [1] |
Weak immune system | Weakened by immunosuppressant medicines (such as after an organ transplant) or by conditions such as HIV infection [1] |
History of STDs | Several types of sexually transmitted diseases, including anal warts, may increase risk [1] |
What complications can anal cancer cause?
The main complication of anal cancer is spread to distant parts of the body, though this is not common [1]. When it does spread, it tends to travel to the liver and lungs [1].
How can anal cancer be prevented and screened for?
Anal cancer cannot be prevented for sure, but practicing safer sex, getting the HPV vaccine and avoiding tobacco can reduce your risk.
Practice safer sex. Reduce your risk by taking measures to prevent STDs — including using a condom every time you have sex and limiting the number of sexual partners [1].
Get the HPV vaccine. Vaccination against HPV infection may reduce your risk of anal cancer and other HPV-related cancers [1]. Ask your healthcare team if an HPV vaccine is right for you.
Don't use tobacco. If you currently use tobacco of any kind, talk with a healthcare professional about strategies to help you quit.
Anal Cancer Screening
Healthcare professionals sometimes recommend screening for people with a high risk of anal cancer — for example, people with HIV, high-risk HPV, those taking medicine to manage their immune system after an organ transplant, or those diagnosed with precancerous cells in the penis, scrotum, cervix, vagina, or vulva [1].
Screening test | What happens |
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 could become cancerous [1] |
Anal HPV test | Cells from the anal canal are tested for infection with HPV [1] |
Digital rectal exam | A gloved finger coated with water-based jelly is inserted into the anus; the professional feels the anal canal and rectum for growths or other signs of cancer [1] |
An honest note on screening: Medical groups don't agree on who should have anal cancer screening or which tests to use [1]. Screening can detect anal cancer when it's small and easier to treat, but studies haven't proved that screening saves lives [1]. Talk about the benefits and risks of screening with your healthcare team.
How is anal cancer diagnosed?
Test or procedure | What it does |
Digital rectal exam | A healthcare professional inserts a gloved finger coated with water-based jelly into the anus and feels the anal canal and rectum for growths or other signs of cancer [2] |
Anoscopy | A thin, flexible tube with a light (anoscope) is inserted through the anal canal and rectum; a lens allows the professional to examine the inside of the anal canal [2] |
Imaging tests | Make pictures of the body to show the location and size of the cancer — including ultrasound, X-ray, MRI, CT scan, and PET scan [2] |
Biopsy | A tissue sample is removed — often collected during an anoscopy using special tools through the anoscope — and tested in a lab to confirm whether it is cancer; other special tests give more details about the cancer cells, which the care team uses to make a treatment plan [2] |
How is anal cancer treated?
Treatment often starts with chemotherapy and radiation therapy [2]. Sometimes surgery is used. When the cancer spreads to other parts of the body, different treatments — chemotherapy on its own and immunotherapy — might be used [2]. The best treatment for you depends on the stage of your cancer, your overall health, and your own preferences [2].
Combined Chemotherapy and Radiation (the Main Approach)
Anal cancer is usually treated with a combination of chemotherapy and radiation. Together, these two treatments enhance each other to kill cancer cells [2].
Chemotherapy treats cancer with strong medicines, often in combination. Some are injected into a vein; others come in pill form.
Radiation therapy treats cancer with powerful energy beams from X-rays, protons, or other sources. A machine directs beams to specific points on the body to kill the cancer cells there.
Radiation is typically given daily over several weeks [2], and the chemotherapy schedule depends on the medicines your team chooses — tailored to your cancer's characteristics and overall health.
Surgery
Situation | The operation |
Cancer that hasn't responded to other treatments | Abdominoperineal resection (APR): the surgeon removes the anal canal, rectum, and part of the colon. The remaining colon is attached to an opening in the abdomen called a stoma; waste leaves the body through the stoma and collects in a colostomy bag [2]. |
Very small anal cancers | The surgeon removes the cancer plus some healthy tissue around it to ensure all cancer cells are removed. This is an option only if the cancer is very small and the surgery won't hurt the anal sphincter muscles that control bowel movements. Chemotherapy and radiation after surgery may also be recommended [2]. |
When Cancer Has Spread
Treatment | How it works |
Chemotherapy | Medicines control the growth of cancer cells throughout the body |
Immunotherapy | A medicine that helps the immune system find and kill cancer cells, which survive by hiding from it. Treatment usually starts with retifanlimab (Zynyz) combined with chemotherapy medicines [2]. |
Palliative Care
Palliative care is a special type of care to help you feel better when you have a serious illness. It can relieve pain and other symptoms, with a team of doctors, nurses, and specially trained professionals working with you, your family, and your care team to improve quality of life. It can be provided at the same time as strong cancer treatments such as surgery, chemotherapy, or radiation, and using it alongside all other appropriate treatments can help people with cancer feel better and perhaps live longer.
Can complementary approaches help people with anal cancer?
Complementary approaches won't kill anal cancer cells, but some may help you cope with side effects such as fatigue [2]. Speak with your healthcare team about:
Gentle exercise — with their OK, start gentle (walking, swimming, yoga, tai chi) and add more as you feel up to it
Managing stress — muscle relaxation, visualization, and journaling
Massage therapy — some massage therapists are specially trained to work with people who have cancer
Acupuncture — some acupuncturists are specially trained to work with people who have cancer
How can people cope with anal cancer?
Coping with anal cancer is helped by asking questions about the disease, staying connected to friends and family, and finding someone to talk with. Three strategies may help you find comfort:
Ask questions about anal cancer. Write down your questions, ask them at your next appointment, and ask your team for reliable sources of information. Knowing more about your cancer and options makes care decisions easier.
Stay connected to friends and family. When loved ones ask how they can help, think of specific tasks — a friend to talk with when you need one, or help caring for your home if you must stay in the hospital.
Find someone to talk with. Ask your team to suggest a counselor, clergy member, or medical social worker with experience helping people facing a life-threatening illness. For support groups, contact the American Cancer Society [2] or ask about local or online groups.
How should you prepare for an anal cancer appointment?
Preparing for an anal cancer appointment means expecting a possible referral to a surgeon, gastroenterologist or oncologist and writing down your symptoms, medicines and questions. Because appointments can be brief, prepare in advance:
Ask about pre-appointment restrictions — for example, you might need to limit what you eat.
Write down your symptoms, including any that may not seem related.
Write down key personal information, including major stresses or recent life changes.
List all medicines, vitamins, and supplements, with doses.
Take a family member or friend along — someone else may remember details you missed or forgot.
Write down questions to ask your healthcare team, ordered from most to least important.
Questions to ask your healthcare professional:
What is the stage of my cancer, and what other tests do I need?
What are my treatment options, and is one best for my type and stage?
What are the potential side effects for each treatment?
Should I seek a second opinion, and am I eligible for clinical trials?
What will determine whether I should plan for a follow-up visit?
Conclusion
Get persistent symptoms checked. Bleeding, pain, itching, or a lump are so often mistaken for hemorrhoids that the most important action is having a healthcare professional examine the area and biopsy any growth.
HPV is the common thread. Most cases follow long-term infection with high-risk HPV (types 16 and 18), which makes the HPV vaccine and safer sex practices your strongest prevention tools.
Treatment often doesn't need major surgery. Combined chemotherapy and radiation is the standard approach; surgery is reserved for specific situations, and immunotherapy has opened new options when the cancer spreads.
Frequently Asked Questions
What is anal cancer and where does it start?
Anal cancer is a growth of cells that starts in the anal canal — the short 1½-inch tube at the end of the rectum, surrounded by sphincter muscles that relax to allow waste to leave the body. For most people it develops after a long-term infection with a high-risk type of HPV in the anal area.
What are the first signs of anal cancer?
Anal cancer may begin without any symptoms. When they appear, signs include bleeding from the anus or rectum, blood in the stool, anal pain, a growth in the anal canal, anal itching, thinner stools or constipation, and a feeling of fullness even after going to the bathroom. These are often mistaken for hemorrhoids.
What causes anal cancer?
Most anal cancers are caused by human papillomavirus (HPV), a common virus passed through sexual contact. HPV causes DNA changes in anal canal cells, making them multiply quickly and survive when healthy cells would die — forming a tumor that can invade tissue and eventually spread [1].
What is the most common type of anal cancer?
Squamous cell carcinoma (SCC). It begins in the flat squamous cells lining the anal canal and the skin ring around the outside of the anus, and most cases are linked to high-risk HPV types 16 and 18 [1]. When it hasn't spread, it is commonly treated with concurrent chemotherapy and radiation.
How is anal cancer treated?
Treatment usually starts with combined chemotherapy and radiation. Surgery is used in certain situations — abdominoperineal resection (APR) with a colostomy for cancers that don't respond, or local removal for very small cancers. If the cancer spreads, chemotherapy and immunotherapy (usually retifanlimab with chemotherapy) are used [2].
Does anal cancer spread?
It is not common for anal cancer to spread to distant parts of the body. When it does, it tends to travel to the liver and lungs, and it is treated with chemotherapy and immunotherapy rather than the standard combined chemo-radiation approach.
Can anal cancer be prevented?
There is no sure way, but you can reduce your risk by practicing safer sex, getting the HPV vaccine, and not using tobacco [1]. People at higher risk — such as those with HIV, high-risk HPV, or immunosuppressant medicines after a transplant — may discuss screening with their healthcare team.
References
Mayo Clinic Staff. Anal cancer - Symptoms and causes. Mayo Clinic. Feb. 04, 2026. https://www.mayoclinic.org/diseases-conditions/anal-cancer/symptoms-causes/syc-20354140
Mayo Clinic Staff. Anal cancer - Diagnosis and treatment. Mayo Clinic. Feb. 04, 2026. https://www.mayoclinic.org/diseases-conditions/anal-cancer/diagnosis-treatment/drc-20354146
Young PM, Golia Pernicka JS, Jing AB, et al. MR imaging of anal cancer. Magn Reson Imaging Clin N Am. 2026;34(4):649-662. PMID: 42855208. https://doi.org/10.1016/j.mric.2026.06.007
Shimoike N, Hida K, Sakamoto T, et al. Stage-dependent differences of long-term outcomes between chemoradiotherapy and surgery for squamous cell carcinoma of the anal canal: a multicenter retrospective cohort study. Int J Clin Oncol. 2026;31(10):2234-2242. PMID: 42629537. https://doi.org/10.1007/s10147-026-03128-6
Miyazaki NL, Matecki MA, Lee S, et al. The THOMAS study: a pilot study for patient-administered anal cancer screening. Dis Colon Rectum. 2026. PMID: 42775545. https://doi.org/10.1097/DCR.0000000000004452
Medical disclaimer
This article is for general informational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment. Always seek the advice of a qualified healthcare provider with any questions about a medical condition.
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