The role of colonoscopy in the assessment of patients with colorectal cancer.

A retrospective review of 176 patients with adenocarcinoma of the colon who underwent total colonoscopy preoperatively demonstrated synchronous carcinomas in 3.4 percent and synchronous polyps in 55.1 percent. Full-column barium enemas (68 patients) failed to identify cancer in 22 percent of patients and synchronous polyps in 58 percent of patients, a statistically significant (P less than 0.001) number of false-negative examinations. Double-contrast barium enemas (30 patients) failed to identify cancer in 27 percent of patients and synchronous polyps in 42 percent of patients, also a statistically significant (P less than 0.007) number of false-negative examinations. Full column and air contrast barium enemas identified all index cancers with distant metastases. Air-contrast barium enemas failed to identify 40 percent of "early" index cancers (confined to the bowel wall, negative nodes), and full-column barium enemas failed to identify 32 percent. The incidence of synchronous carcinoma and polyps underscores the need for total colon evaluation when a primary carcinoma is detected. Because of the poor accuracy of barium studies, total colonoscopy is the method of choice for this evaluation.