Screening for colorectal cancer. Use of a new protocol may reduce death rates.

The goal of screening for colorectal cancer is to find early, asymptomatic cancers and adenomatous polyps that are 1 cm or more in diameter or that are villous or tubulovillous histologically. A study using fecal occult blood testing with rehydration and no sigmoidoscopy found that deaths from colorectal cancer can be reduced by screening. Although this protocol is effective in screening, whether it is the optimal approach remains to be determined. Flexible sigmoidoscopy as a screening method has not been studied, except in nonrandomized tests. However, since endoscopic diagnosis and treatment is ultimately the means by which benefits from fecal occult blood testing are realized and since flexible sigmoidoscopy visualizes more than half of colon cancers and colon polyps, it seems logical that this method would be an effective screening test. Whether doing both rehydrated fecal occult blood testing and flexible sigmoidoscopy enhances results is unknown. It seems appropriate to use the rehydration method when fecal occult blood testing is done and flexible sigmoidoscopy when endoscopy is done. Fecal occult blood testing should precede sigmoidoscopy so that patients with a positive result can go directly to colonoscopy and avoid two procedures.