Anal cancer is an uncommon type of cancer that occurs in the anal canal. The anal canal is a short tube at the end of your rectum that measures 1 1/2 inches in length (about 4 centimeters). Muscles (anal sphincters) that surround the anal canal relax to allow waste to leave your body.

Anal cancer can cause signs and symptoms such as rectal bleeding and anal pain. Anal cancer symptoms may mimic those of more common conditions, such as hemorrhoids. For this reason, people with anal cancer may not see their doctors right away.

Most cases of anal cancer are diagnosed at an early stage — when treatment provides the best chance for a cure.

What are the symptoms?

Anal cancer signs and symptoms include:

  • Bleeding from the anus or rectum
  • Pain in the area of the anus
  • A mass or growth in the anal canal
  • Anal itching

The signs and symptoms of anal cancer aren’t specific to this disease. Some people mistake their signs and symptoms for more common conditions, such as hemorrhoids, and don’t see their doctors. Talk to your doctor about any signs and symptoms that bother you, especially if you have any factors that increase your risk of anal cancer. Treatment for anal cancer is more likely to succeed if cancer is found at an early stage.

What are the risk factors?

Several factors have been found to increase the risk of anal cancer, including:

  • Older age. Most cases of anal cancer occur in people age 50 and older.
  • Many sexual partners. Men who have many sexual partners over their lifetimes have a greater risk of anal cancer.
  • Anal sex. Men who engage in anal sex have an increased risk of anal cancer.
  • Smoking. Smoking cigarettes may increase your risk of anal cancer. Former smokers have only a slightly elevated risk of anal cancer.
  • Human Papilloma Virus (HPV). HPV infection increases your risk of several cancers, including anal cancer and cervical cancer. HPV infection is a sexually transmitted disease that can also cause genital warts. HPV may cause cells in the anal canal to appear abnormal — a condition called anal squamous intraepithelial lesions (ASIL). The abnormal cells associated with ASIL aren’t cancer, but they may develop into anal cancer. However, some people with ASIL never develop anal cancer.
  • Drugs or conditions that suppress your immune system. People who take drugs to suppress their immune systems (immunosuppressive drugs), including people who have received organ transplants, may have an increased risk of anal cancer. Long-term use of corticosteroids, such as those prescribed to control autoimmune disorders, also may increase the risk of anal cancer. HIV — the virus that causes AIDS — suppresses the immune system and increases the risk of anal cancer.

How is anal cancer tested for and diagnosed?

Tests and procedures used to diagnose anal cancer include:

  • Examining your anal canal and rectum for abnormalities. During a digital rectal exam (DRE), your doctor inserts a gloved, lubricated finger into your rectum. He or she feels for anything unusual, such as growths. DRE isn’t used to diagnose anal cancer, but it can give your doctor an indication of what further testing might be appropriate.
  • Visually inspecting your anal canal and rectum. Your doctor may use a short, lighted tube (anoscope) to inspect your anal canal and rectum for anything unusual.
  • Taking sound wave pictures of your anal canal. In order to create a picture of your anal canal, your doctor inserts a probe, similar to a thick thermometer, into your anal canal and rectum. The probe emits high-energy sound waves, called ultrasound waves, which bounce off tissues and organs in your body to create a picture. Your doctor evaluates the picture to look for anything abnormal.
  • Removing a sample of tissue for laboratory testing. If your doctor discovers any unusual areas, he or she may take small samples of affected tissue (biopsy) and send the samples to a laboratory for analysis. By looking at the cells under a microscope, doctors can determine if the cells are cancerous.

What’s the main point I should take away?

Be proactive about taking care of your anal health and talk with your healthcare provider about getting screened.

Adapted from Mayo Clinic’s anal cancer resource: