When your body makes stool (bowel movement), it sits in your rectum. The anus helps you control the movement of stool from the rectum to the outside of your body. Anal cancer is caused by anal cells growing out of control. As the number of cells grows, they form a tumor.

Anal cancer that has spread from the anus to another part of the body is called metastatic cancer.

Risk Factors

Some risk factors of anal cancer are:

Infection with the human papillomavirus (HPV) or HIV.
Smoking.

Signs and Symptoms of Anal Cancer

Signs and symptoms of anal cancer can be:

Bleeding when passing stool.
Pain or feeling of fullness in the anus.
Itchiness.
Discharge.
A change in normal bathroom habits.
Pain when touched.

Screening Tests

If your healthcare providers think you may have anal cancer, they will do a full exam of your body and ask you questions about your health history. Your provider may do a digital rectal exam, an anal pap smear, and look at your anus with a scope. They may also do some imaging tests like ultrasound, CT scan, MRI, and PET scan.

Diagnosis of Anal Cancer

After doing a screening test, if your healthcare provider thinks you have anal cancer, they will do a biopsy. A biopsy:

Looks at a piece of the anus for cancer cells.
Is used to find out the cancer type, how normal it is (grade), and if it has spread (metastasized).
The biopsy may be done using a needle, small pair of scissors, or clamps to remove a small piece of tissue.

A pathology report summarizes these results and is sent to your healthcare provider, often 5 to 10 days after the biopsy. This report is an important part of planning your treatment. You can ask for a copy of your report for your records.

Staging Anal Cancer

To guide treatment, anal cancer is "staged." This stage is based on:

Size of the tumor and where the tumor is.
Whether cancer cells are in the lymph nodes.
Whether cancer cells are in other parts of the body.

Stages range from stage I (one) to stage IV (four). Stage I means the smallest, most confined tumors and stage IV means tumors that have spread to other parts of the body, also called metastatic cancer. The stage and type of anal cancer will guide your treatment plan.

Treatment

Treatments often used for anal cancer are:

Radiation therapy is the use of high-energy x-rays to kill cancer cells.
Chemotherapy is the use of medication to kill cancer cells.
Chemoradiation is the use of radiation and chemotherapy at the same time.
Surgery can be used in some cases to remove the tumor.

This article is a basic guide to anal cancer. You can learn more about your type of anal cancer and treatment by using the links below.

Anal Cancer: Staging and Treatment