['The validity of mass screening using fecal occult blood testing remains controversial. In addition, no controlled clinical study has yet been performed to show the usefulness of sigmoidoscopy. The purpose of the present study was to compare the surgical results achieved in asymptomatic patients with colorectal cancer detected by screening with those in symptomatic individuals.', 'A total of 285 patients underwent a surgical resection of colorectal cancer between 1991 and 1997 at our institution. Among them, 233 patients had complaints related to cancer at the time of diagnosis. In contrast, 52 were asymptomatic. In those 52 patients, colorectal cancer had been suspected based on routine screening including fecal occult blood testing, colonoscopy and/or elevated serum levels of carcinoembryonic antigen.', 'Early stage of colorectal cancer was more frequently seen in asymptomatic patients than in symptomatic patients P < 0.01. The survival rates for asymptomatic patients was also superior to those of symptomatic patients P < 0.05.'] Is the detection of colorectal cancer at an asymptomatic stage by screening useful?