Anal melanoma is a very rare cancer that can be difficult to diagnose. Many symptoms such as fatigue, rectal bleeding and changes in bowel habits are symptoms of this condition as well as other bowel diseases. Treatment for this kind of cancer is based on the stage and extent of the cancer, the patient's general health and the location of the tumor.
Significance
According to the American Cancer Society, approximately 5,260 new cases of anal cancer will be diagnosed and nearly 720 individuals will die from the disease in the U.S. in 2010. The American Cancer Society estimates that only about 1 to 2 percent of these anal cancers are anal melanomas. According to MacMillan Cancer Support, anal melanoma comprises 1 percent of all melanomas. This kind of cancer is rare because melanoma typically develops on areas of the body that have had prolonged exposure to sunlight.
Surgery
According to MacMillan Cancer Support, there are two types of surgery typically used in the treatment of anal melanoma: wide local excision and abdominoperitoneal, or AP, resection. A wide local excision involves removing the tumor or cancerous area with a margin of healthy tissue surrounding it. This procedure is usually done when small tumors are on the outside of the anus, says MacMillan Cancer Support. No colostomy is needed with this surgery. The AP resection removes both the anus and rectum, as well as some lymph nodes in the area to check for cancer; this requires that a permanent colostomy be made. This surgery is typically used to treat larger tumors, cancer involving the anal sphincter and those melanomas that recur after local excision.
Radiation Therapy
Radiation, the use of high-energy rays, helps kill cancer cells that may be remaining after a wide local excision or a local resection, says MacMillan Cancer Support. Radiation also helps reduce the risk of the cancer recurring. If the anal melanoma is advanced, radiation may be used to help treat symptoms and reduce pain. Side effects of radiation therapy for anal cancer can include changes in bowel functioning, diarrhea, fatigue and blistering around the anal area.
Chemotherapy
Chemotherapy uses anti-cancer drugs to kill cancer cells and keep them from dividing. It can be given after surgery or if surgery is not possible. The most commonly used chemotherapy drug for anal melanoma is dacarbazine, also known as DTIC, according to MacMillan Cancer Support. It is typically administered intravenously; side effects can include increased risk of infection, anemia, nausea or vomiting and mouth sores.
Survival
Anal melanoma is known as a mucosal melanoma because of the tissues in which it is found, and according to the Merck Manuals Online Medical Library, carry a poor prognosis. If the melanoma has spread to the lymph nodes, five-year survival rates range from 25 to 70 percent, depending on how many nodes are cancerous. If the melanoma has spread to distant sites in the body, the five-year survival rate is approximately 10 percent.
