Key takeaways

  • Anal cancer occurs in the anus, which is at the end of the gastrointestinal tract. Anal cancer symptoms can include rectal bleeding, itching, pain, changes in bowel movements, and more.
  • Anal cancer can occur without an apparent cause. Some factors, including HPV, HIV, smoking tobacco, and more, can increase a person’s risk of anal cancer.
  • Treatment for anal cancer will depend on individual factors, including a person’s age, health, and tumor characteristics. Early diagnosis of anal cancer leads to a more favorable outlook.

At first, anal cancer may resemble hemorrhoids. Anyone who notices changes in the anal area should see a doctor. Often, they do not have cancer. If they do, an early diagnosis is more likely to lead to a positive outcome.

This article explains everything about anal cancer, including its types, prevalence, symptoms, causes, treatment, and outlook.

The use of binary terms such as “male” and “female” or “men” and “women” in this article reflects the language of the sources we’ve used. Unless otherwise noted, it’s unclear whether the research we reference included participants with expansive gender identities.

Anal cancer is any cancer that affects the anal region, which is at the end of the digestive tract. According to the American Cancer Society (ACS), this can involve:

  • cancers of the anal canal
  • cancers of the perianal skin

Below are some types of cancers that can affect the anal region.

Squamous cell anal carcinoma

Squamous cell carcinomas make up 9 out of 10 cases of anal cancers in the United States.

This type of anal cancer begins in the squamous cells that line the anal canal and perianal skin. They grow beyond the surface and into the deeper lining of the anal region.

Adenocarcinoma

Adenocarcinomas can begin in the following parts of the anal region:

  • in the cells lining the upper part of the anal canal, near the rectum
  • in the glands that release secretions into the anal canal
  • in the sweat glands in the perianal skin

Basal cell carcinoma and melanoma

Basal cell carcinomas and melanomas are both types of skin cancer. In the anal region, these types of cancers may affect the perianal skin or anal lining.

Precancerous lesions

Precancers are changes in the anal regions that can develop into cancer over time.

Doctors may refer to precancers as dysplasia and categorize them into two different grades depending on the appearance of the cells.

Cells that appear to look as expected are grade one or low-grade. Atypical cells are grade two or high-grade. High-grade precancers are more likely to become cancerous over time.

Anal cancer is rare, but the number of new cases is rising. Every year, around 50,000 new cases occur globally, 10,000 of which occur in the United States.

According to the ACS, anal cancer is rare before 35 years of age. The average age of diagnosis is when a person is in their early 60s. For 2026, the ACS estimates there will be around 11,270 new cases of anal cancer in the United States.

Anal cancer is different from and less common than colorectal cancer, which is cancer of the colon or rectum.

Symptoms of anal cancer include:

Some of these symptoms can also be the result of more common health issues, such as hemorrhoids, anal warts, or anal tearing. However, a person should see a doctor if these changes occur to rule out cancer.

Anal cancer develops when cells grow uncontrollably and form a tumor. Experts do not know exactly what causes anal cancer, and in some cases, there is no apparent cause.

However, there are several risk factors that can increase the likelihood of developing anal cancer, including:

  • Human papillomavirus (HPV): HPV infection is associated with anal cancer, although it does not always lead to anal cancer. Subtypes HPV-16 and HPV-18 are more commonly linked with anal cancer.
  • HIV infection: People with HIV may have a higher risk of anal cancer compared to those in the general population.
  • Tobacco use: Research associates smoking tobacco with a higher risk of anal cancer, anal cancer recurrence, and higher mortality rates.
  • Immunosuppression: People with a suppressed immune system have a higher risk. This can be due to autoimmune conditions, medications, and organ transplants.
  • Age: As people get older, their chances of developing anal cancer increase. This could be due to the accumulation of cell damage.
  • Sex and race: Female anal cancer is more common than male anal cancer. Black men also have a higher risk of anal cancer.
  • Sexual activity: Having multiple sexual partners and engaging in receptive anal sex can increase a person’s risk of anal cancer.
  • Other cancers: People who have had another HPV-linked cancer seem to have a higher risk of anal cancer. This can include vaginal or cervical cancer or a history of precancerous cells in the cervix.

Is it possible to prevent anal cancer?

People cannot change or manage some of the risk factors for anal cancer. However, lifestyle changes such as quitting or avoiding smoking, having the HPV vaccination, and practicing safe sex may help reduce a person’s risk.

People should seek medical advice for any changes that affect the anus, even if these give no suggestion of cancer.

An individual can also ask a doctor about screening if they have a high risk, such as HPV infection.

To diagnose anal cancer, a doctor will ask the person about their symptoms and medical history and carry out a physical examination.

If the doctor believes anal cancer may be present, they will refer the person to a colorectal surgeon, a doctor who specializes in bowel conditions. The specialist may perform several tests, including the following:

  • Rectal examination: The doctor may insert a proctoscope, anoscope, or sigmoidoscope into the anus to examine the area in more detail. This will help determine if the person needs a biopsy.
  • Biopsy: The doctor will take a small tissue sample from the anal area and send it to the lab for examination under a microscope. If the biopsy reveals cancerous tissue, the person may need further tests.
  • Imaging scans: A CT, MRI, or ultrasound scan can help confirm biopsy results. This may include a rectal ultrasound, where the doctor inserts an instrument into the anus to be able to see the tissues more clearly.

Treatment for anal cancer will be different for each person. Factors that affect treatment options include:

  • the size of the tumor
  • the cancer grade, as high-grade cancers can be more aggressive
  • whether cancer has spread
  • the individual’s age and overall health

Surgery, chemotherapy, and radiation therapy are the main treatment options.

Surgery

The type of surgery depends on the size and position of the tumor.

  • Lower anterior resection: The surgeon removes a small tumor and some surrounding tissue. This is only possible if cancer does not affect the anal sphincter, or muscle. After this procedure, the person will still be able to have a bowel movement.
  • Abdominopelvic resection: The surgeon removes the anus, rectum, and a section of the bowel. Because this involves the removal of the anal sphincter, the person will not be able to have a bowel movement, and so the surgeon will construct a colostomy.

A person with a new colostomy may feel anxious, but they can lead a typical life, play sports, and be sexually active. However, a doctor will try to avoid surgery that changes physical structures, as far as possible.

Key terms: Colostomy

In a colostomy, a surgeon brings the end of the bowel to the outside of the abdomen. A bag then covers the stoma, or opening, and collects the stools outside the body.

Chemotherapy and radiotherapy

A doctor may recommend chemotherapy, radiation therapy, or both. People may have these treatments at the same time or one after the other. If these approaches work, the person may not need a colostomy.

  • Chemotherapy: This treatment uses drugs that kill cancer cells or prevent them from dividing. The doctor may give them orally or by injection.
  • Radiation therapy: This treatment uses high-energy rays that destroy cancer cells. In external radiation, a machine produces a beam that targets the malignant cells. Internal radiation involves inserting radioactive material into the body, from where it emits ongoing radiation.

Both radiation therapy and chemotherapy can have adverse effects. Radiation therapy can lead to soreness and damage around the anus.

A doctor may prescribe therapies to reduce the severity of side effects. They will work with the individual to choose the best option.

Immunotherapy

Specific drugs can boost the immune system’s defense from some types of cancer.

Some research suggests immunotherapy, checkpoint inhibitor medications, may improve outcomes for people in the second line of therapy with advanced anal cancer.

The outlook for anal cancer will depend to some extent on the stage of cancer at diagnosis. Experts use statistics to work out how many people can expect to live another five years or more after a cancer diagnosis.

According to the ACS, the chances of living at least 5 years with anal cancer are:

  • 85% for localized cancer, which has not spread beyond the original site.
  • 70% for regional cancer, which has only spread to nearby tissues.
  • 36% for distant cancer, which affects other areas or organs, for example, the liver.

These predictions use disease figures from 2015 to 2018. As medical knowledge and treatments improve, so should the outlook.

Other factors affecting the outlook include the individual’s overall health and age.

However, anyone who receives a cancer diagnosis at an early stage will have a better chance of effective treatment than those whose diagnosis is later. For this reason, it is essential to see a doctor soon if changes occur in or around the anus.

It is often possible to detect anal cancer in the early stages, especially if it occurs in the lower part of the anal canal.

Anal cancer is a relatively rare cancer, but its incidence is on the rise. Symptoms may include rectal bleeding and changes in stools, although these symptoms can also indicate more common health issues, such as hemorrhoids.

Having the HPV vaccination and seeing the doctor about any changes in the anal area can help reduce the risk of anal cancer and its complications. People with a higher risk may benefit from asking their doctor about screening.