Anal Cancer Library
Learn about Anal Cancer
Anal cancer is a disease in which malignant (cancer) cells form in the tissues of the anus.
The anus is the end of the large intestine, below the rectum, through which stool (solid waste) leaves the body. The anus is formed partly from the outer skin layers of the body and partly from the intestine. Two ring-like muscles, called sphincter muscles, open and close the anal opening and let stool pass out of the body. The anal canal, the part of the anus between the rectum and the anal opening, is about 1-1½ inches long.
The skin around the outside of the anus is called the perianal area. Tumors of the perianal skin that do not involve the anal sphincter are usually treated the same as anal cancers, although local therapy (treatment directed to a limited area of skin) may be used for some.
Most anal cancers are related to human papillomavirus (HPV) infection.
Risk factors for anal cancer include the following:
- Being infected with human papillomavirus (HPV).
- Having a condition or disease that causes a weakened immune system, such as human immunodeficiency virus (HIV) or an organ transplant.
- Having a personal history of vulvar, vaginal, or cervical cancers.
- Having many sexual partners.
- Having receptive anal intercourse (anal sex).
- Smoking cigarettes.
Signs of anal cancer include bleeding from the anus or rectum or a lump near the anus.
These and other signs and symptoms may be caused by anal cancer or by other conditions. Check with your doctor if you have any of the following:
- Bleeding from the anus or rectum.
- A lump near the anus.
- Pain or pressure in the area around the anus.
- Itching or discharge from the anus.
- A change in bowel habits.
Tests that examine the rectum and anus are used to diagnose anal cancer.
The following tests and procedures may be used:
- Physical exam and health history: An exam of the body to check general signs of health, including checking for signs of disease, such as lumps or anything else that seems unusual. A history of the patient’s health habits and past illnesses and treatments will also be taken.
- Digital rectal examination (DRE): An exam of the anus and rectum. The doctor or nurse inserts a lubricated, gloved finger into the lower part of the rectum to feel for lumps or anything else that seems unusual.
- Anoscopy: An exam of the anus and lower rectum using a short, lighted tube called an anoscope.
- Proctoscopy: A procedure to look inside the rectum and anus to check for abnormal areas, using a proctoscope. A proctoscope is a thin, tube-like instrument with a light and a lens for viewing the inside of the rectum and anus. It may also have a tool to remove tissue samples, which are checked under a microscope for signs of cancer.
- Endo-anal or endorectal ultrasound: A procedure in which an ultrasound transducer (probe) is inserted into the anus or rectum and used to bounce high-energy sound waves (ultrasound) off internal tissues or organs and make echoes. The echoes form a picture of body tissues called a sonogram.
- Biopsy: The removal of cells or tissues so they can be viewed under a microscope by a pathologist to check for signs of cancer. If an abnormal area is seen during the anoscopy, a biopsy may be done at that time.
Certain factors affect the prognosis (chance of recovery) and treatment options.
The prognosis depends on the following:
- The size of the tumor.
- Whether the cancer has spread to the lymph nodes.
The treatment options depend on the following:
- The stage of the cancer.
- Where the tumor is in the anus.
- Whether the patient has human immunodeficiency virus (HIV).
- Whether cancer remains after initial treatment or has recurred.