What Is Anal Cancer?

Approximately 8,600 people will be diagnosed with anal cancer in the US and about 1,400 in the UK annually.

If you are reading this, the chances are you or a loved one has experienced an anal cancer diagnosis. This diagnosis can bring with it more questions than answers. This fact page is intended to provide you with some of the key facts and figures about anal cancer. We encourage you to contact us with any questions or concerns. We are here for you.

What is Anal Cancer?

Cancer that develops in the cells and tissue of the skin lining on either the inside or outside of the anus is called anal cancer.

The anus is an opening to the outside of the body from which stool exits the body. It is below the rectum and is the last part of the gastrointestinal tract.

Some confuse anal cancer with rectal cancer due to the proximity, but the two diseases and treatments of the diseases are different. Colorectal cancer, for example, is primarily adenocarcinoma, and anal cancer is usually squamous cell carcinoma (SCC).

More women than men are diagnosed with anal cancer each year. In the US, about 5,530 women and 2,770 men are newly diagnosed with anal cancer annually. In the UK, annual anal cancer diagnoses are comprised of roughly 1,000 women and 480 men.

In the US, the risk of being diagnosed with anal cancer in one’s lifetime is about 1 in 500. This risk is slightly higher in women than in men. In the UK, one’s lifetime risk of bowel cancer is 6% for women and 7% for men. Anal cancer makes up about 2% of bowel cancers in the UK.

The average age at diagnosis in the US is 60. In the UK the peak is 65.

It is estimated that over 91% of anal cancer cases are caused by human papillomavirus (HPV).

Worldwide, HPV causes 5% of all cancer. In addition to anal cancer, HPV also causes cervical, vaginal, vulvar, penile and head and neck cancers.

Anal Cancer Types

There are three types of anal cancer. Treatment options vary depending on the type of anal cancer.

  • Squamous cell carcinoma (SCC) starts in the outer lining of the anus. Approximately 90% of anal cancers are squamous cell carcinoma and result from HPV most of the time
  • Basal cell carcinoma is a skin cancer that occurs in the area around the anus. They account for only a very small number of anal cancers and are considered a type of squamous cell carcinoma.
  • Adenocarcinoma is either in the lining of the anus near the rectum or in the anal glands that produce mucous.
  • Malignant melanoma occurs in the cells of the skin of the anal lining responsible for pigment and makes up ≤2% of anal cancers. Malignant melanoma may also be called skin cancer.

Anal Cancer Staging

Staging is used by doctors to describe how far a cancer has spread. Treatment options and outlook depend on a cancer’s stage.

There are four stages of anal cancer according to the National Cancer Institute:

  • Stage I: Cancer exists and the tumour is 2 centimetres (cm) or smaller.
  • Stage II: The tumour is larger than 2cm.
  • Stage IIIA: The tumour is of any size and has spread to the lymph nodes near the rectum or to nearby organs such as the vagina, bladder or urethra.
  • Stage IIIB: The tumour is of any size and may have spread to the lymph nodes in the rectum, pelvis, and/or groin, and possibly to nearby organs.
  • Stage IV: The tumour is of any size and may have spread to the lymph nodes or nearby organs and has also spread to distant parts of the body.

Please find more information on anal cancer at the following links:

Newly Diagnosed

Treatment for Anal Cancer

Living with the Side Effects

Recurrent and Advanced Cancer

Questions to ask your Doctor

Facing an Anal Cancer Diagnosis


Causes & Risk Factors

Anal Precancer


The information is presented as downloadable documents that you may add to your library of resources.

Anal Cancer

Anal Cancer: The Facts
Information on anal cancer, testing, and treatment.

Anal Cancer: Questions to Ask Your Doctor
Knowing the right questions to ask your doctor after a diagnosis can be tricky. The questions outlined in this document will help you develop a list of your own questions to better inform your anal cancer experience.