Anal cancer is a disease in which malignant (cancer) cells form in the tissues of the anus. The anus is located at the end of the large intestine, below the rectum, through which solid waste leaves the body. The anus is formed partly from the outer skin layers and partly from the intestine. The anal canal, the part of the anus between the rectum and the anal opening, is about 1½ inches long. Anal carcinoma (cancer) is unique and can be distinguished from all other gastrointestinal tumors. It is mainly a local-regional cancer, with a metastatic potential (possibility of spreading to other body tissues) in only 15% of patients. The April 23/30, 2008, issue of JAMA includes an article evaluating current therapies for the treatment of anal carcinoma.
Gender—Women have a higher risk than men.
Age—Most cases occur in individuals aged 50 years and older.
Multiple sexual partners
Human papillomavirus (HPV)—a sexually transmitted virus that can cause genital warts and increases the risk of anal and cervical (bottom of the womb) cancers
Drugs or conditions that suppress the immune system—Long-term use of corticosteroid drugs and the presence of HIV (the virus that causes AIDS) have both been linked to an increased risk of anal cancer.
Anal fistulas—presence of abnormal openings along the anal canal
Individuals may have bleeding from the anus, pain or pressure in the area, itching or discharge from the anus, or a lump near the anus. Since successful treatment depends on early recognition, see your doctor for evaluation if you experience any of these problems.
Physical examination and medical history
Digital rectal examination (DRE)—The doctor inserts a lubricated, gloved finger into the anus to feel for lumps or masses that may indicate an abnormality.
Anoscopy—visual examination of the anus and lower rectum using a short lighted tube
Endo-anal ultrasound—An ultrasound probe is inserted into the anus and used to bounce high-energy sound waves off internal tissues or organs. The acquired echoes form a sonogram (picture) of the body tissues.
Biopsy—removal of tissue samples that can be viewed under a microscope to check for signs of cancer
The prognosis (chance of recovery) depends on the size, location, and spread of the tumor. Treatment options depend on the location of the tumor, the stage of the cancer, whether the patient has HIV, and whether cancer remains after the initial treatment or has recurred. Prior to the 1970s, treatment focused on surgical removal of the tumor, but the main treatments now are chemoradiation therapies (anti-cancer drugs combined with radiation), with surgery reserved for patients who have residual disease after such treatment.
American Cancer Society
National Cancer Institute
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Sources: American Cancer Society, National Cancer Institute
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Zeller JL, Lynm C, Glass RM. Anal Cancer. JAMA. 2008;299(16):1980. doi:10.1001/jama.299.16.1980