Colorectal cancer: a primary care approach to screening

The adenomatous polyp is the precursor of most--if not all--colorectal cancers. The average 10 to 12 years that it takes for a polyp to undergo malignant degeneration provides a window of opportunity to identify and remove benign neoplasms, before they become invasive cancers. The incidence of colorectal cancer rises significantly after age 50 and doubles with each successive decade. For screening asymptomatic patients age 50 and older, the fecal occult blood test and flexible sigmoidoscopy are the methods of choice. Recommendations for screening higher-risk individuals are based upon the relative risk of colon cancer in various subgroups, based on family and individual history.