High doses of aspirin ward off colon cancer. Longterm use may offer protection, but risk stomach bleeding.

CHICAGO - Long-term use of aspirin does help ward off colon cancer, but only at high doses that could cause gastrointestinal bleeding, researchers said on Tuesday.

Previous studies have shown that patients with a history of colon polyps or colon cancer who take aspirin regularly can prevent recurrence, and researchers at Massachusetts General Hospital and Brigham and Women's Hospital in Boston sought to determine at what levels the painkillers were effective.