The lower end of the intestines is called the anus; there is a tube called the anal canal that connects the bottom part of the large intestine to the anus and the outside of the body, according to the American Cancer Society. When cancer forms in the anus or anal canal, it is called anal carcinoma. This is different than rectal carcinoma or colorectal cancer.
Significance
Anal carcinoma is rare; only about 5,290 new cases were diagnosed in the United States in 2009, according to the American Cancer Society. That same year, the disease killed approximately 710 individuals. Anal carcinoma is more commonly diagnosed in women than men, and tends to strike individuals over the age of 60.
Types
There are different kinds of anal carcinoma, with squamous cell carcinoma being the most common, according to the American Cancer Society. These cancers develop in the cells lining the anal canal and the cells lining the anal margin. Adenocarcinomas are cancers that start in the glands in the anal mucosa, but these are typically classified as rectal cancers. Paget's disease is cancer that spreads through the top layers of skin; these can start anywhere on the body and may be found on the perianal area. Malignant melanoma may also begin in the anus; these only account for 1 percent to 2 percent of anal cancers, says the American Cancer Society.
Features
Signs and symptoms of anal cancer can include rectal bleeding or itching, pain around the anus, any abnormal anal discharge, changes in the diameter of bowel movements, and swollen lymph nodes in the anus or groin. These symptoms may also occur with noncancerous conditions such as anal fissures or hemorrhoids, so an accurate diagnosis by a health care provider is important.
Identification
To accurately diagnose anal cancer, various tests and exams may be done. A physical exam and medical history are performed, along with a digital rectal exam, where the health care provider inserts a finger into the rectum to feel for anything abnormal. The National Cancer Institute also lists a proctoscopy, in which a small tube with a light on it is used to examine the inside of the rectum; a rectal ultrasound; and a biopsy as procedures that help diagnose the disease. Once it is diagnosed, the cancer will be staged, from Stage 0, carcinoma in situ, which is noninvasive cancer, to Stage IV, which is metastatic disease.
Treatment
The National Cancer Institute describes three standard methods to treat anal cancer: radiation therapy, chemotherapy and surgery. Radiation therapy uses high energy rays to kill cancer cells and slow down cancer growth, and can be administered externally by a machine, or given internally with radioactive pellets placed in the cancer. Chemotherapy is the use of drugs to kill cancer cells; these medications are able to travel through the bloodstream and kill cancer cells throughout the body. Surgery may be done to remove the tumor or part or all of the anus, rectum and colon, depending on the extent to which the cancer has spread. Treatment typically involves more than one mode of therapy.
Time Frame
The five-year survival rate is the percentage of individuals who live at least five years post-diagnosis. For anal cancer, the overall five-year survival rate, which includes those with local and widespread disease, is 58 percent for men and 69 percent for women, according to the American Cancer Society. For localized cancers, which encompasses Stages I and II anal cancers, the overall five-year survival rate is nearly 80 percent; for regional anal cancer, which is Stage IIIA, the rate is 57 percent, and for Stages IIIB and IV, the survival rate is approximately 17 percent.
