Cancer of the Colon is more common than you would imagine. Your lifetime risk is about 1 out of 18, and it is the third most common cancer killer of men and women. About 75% of colon cancers occur in patients with no family history of the cancer, and so experts agree that routine screening after the age of 50 is worthwhile in most individuals. Flexible sigmoidoscopy screens the first 1/3 of the colon, while Colonoscopy (which is more expensive and requires a more thorough flushing) screens the entire colon. About 25-30% of colon cancers occur outside the reach of the shorter scope. The possibility of cure is related to how deeply the tumor invades into the colon and if it spreads to surrounding tissues. Treatment is usually surgical and may involve radiation and/or chemotherapy.