Radiologic approach to the detection of colorectal neoplasia.

Patients with early colorectal carcinoma detected by screening have a high survival rate. Most colorectal carcinomas evolve in preexisting adenomatous polyps, and the incidence of this malignant disease can be reduced by endoscopic polypectomy. Radiologic examination usually cannot differentiate between a benign polyp and a small carcinoma, which heightens the importance of their colonoscopic removal and subsequent histologic examination. The double-contrast enema has a higher degree of sensitivity for the detection of polyps, and probably also for early carcinoma, than the single-contrast enema. Because many of these lesions are asymptomatic, the double-contrast enema should be the standard radiologic examination of the colon in adults. This view has been championed by others and the technique has become more widely adopted. Its use contributes to the effort to reduce mortality from colorectal carcinoma.