Intraoperative colonoscopy for the diagnosis of multiple cancers of the large intestine.

Seventeen patients with multiple simultaneous cancers of the large intestine were investigated. Three out of 4 patients with multiple advanced cancers were correctly diagnosed preoperatively. Multiple cancerous lesions of early and advanced stages coexisted in 13 patients, and it was possible to diagnose the existence of multiple cancers in only 5 preoperatively. A study on the preoperative detectability of coexisting early cancers showed that early lesions located distally to the advanced ones were frequently detected, however, subsidiary lesions located proximally tended to be overlooked. Hence, intraoperative colonoscopy was performed in patients with cancer of the large intestine whenever there was a portion that had not been adequately inspected prior to surgery. Of 31 patients subjected to this examination, 5 had a total of 7 polypoid lesions, in one case we found evidence of a small advanced cancer which was not detected preoperatively.