Abstract
A total of 1,834 cases of colorectal cancers were divided into two diagnostic groups and studied. The ratio of smaller, less advanced carcinomas to the total number of colorectal cancers diagnosed by electronic videoendoscopy has increased as compared to the ratio in cases diagnosed by fiberscopy. This seems to be largely influenced by concomittent developments such as the implementation of colorectal cancer screening assisted by the popularization of immunological fecal occult blood tests and the increase in number of examinees. On the other hand, the use of the electronic videoendoscopy has been accompanied by increases in the diagnosis of minute carcinomas measuring 5 mm or less and flat carcinomas which were previously difficult to diagnose. Under these circumstances, endoscopic mucosal resection has gained popularity, widening the spectrum of therapeutic options. Nonetheless, endoscopic treatment also has been associated with increases in cases requiring laparotomy when carcinoma was found in the resected margin or those demonstrating invasion in the submucosa. This may be one result of the more aggressive application of endoscopic treatment, but the histologically recognized inability to detect carcinoma in the resected intestinal tract leaves room for improvement.