Surgery is the main treatment for colon cancer and removal of the involved colon is required. If the cancer is located near the rectum, a colostomy may be necessary. For stage I and II colon cancer, surgery is usually the only treatment. For stage III or IV colon cancer, chemotherapy is necessary after surgery. There is also some suggestion that chemotherapy may also be helpful in some selected stage II patients. Chemotherapy involves a course of drugs which are toxic to cancer cells.