Colon (colorectal) cancer affects the inner wall of the large intestine and intestinal cancer affects the wall of the small intestine. It is the 3rd leading cause of cancer in males and the 4th in females. Most colorectal cancers develop from polyps and risk factors include heredity, colon cysts and long-standing ulcerative colitis. Generally cancerous cells in the colon are preceded by the presence of benign cells called polyps. Polyps are rarely accompanied by symptoms, but they can be detected through screening tests (colonoscopies) and removed before they become cancerous. Screening and early diagnosis are critical to colon cancers and both surgery and chemotherapy are used to treat the condition.