Implementation of colon cancer screening: techniques, costs, and barriers.

Colorectal cancer and breast cancer are the only cancer sites for which evidence on the efficacy of screening is available from randomized trials. The trials on colon cancer screening in the United States and Europe used the fecal occult blood test as the primary screen, but randomized trial data are not yet available on endoscopy (flexible sigmoidoscopy to 60 cm), and no randomized, controlled trials of colonoscopy as a screening test are in progress. This article reviews colorectal cancer screening from an epidemiologist's perspective to provide the theoretic evidence-based underpinning for the role of the gastroenterologist in colorectal screening.