Mass Screening for Colorectal Cancer by Testing for Occult Blood under a Restricted Diet and using a Questionnaire

Because of the recent increase in the incidence of colorectal cancer in Japan, attempts were made to find an effective method for screening asymptomatic patients with this cancer. A total of 12, 520 participants in Osaka were screened in a 2-year program from April 1982 by testing for fecal occult blood under a restricted diet, and using a medical questionnaire. Occult blood in feces was examined for 3 consecutive days using one guaiac-impregnated slide (Shionogi B) each day. This slide was about twice as sensitive as the Hemoccult slide. Further diagnostic work-ups were required in 3, 434 individuals, of which 2, 602 (75.7 %) were due to positive occult blood. Proctosigmoidoscopy was performed in 2, 214 (64.4 %) of these persons, barium enema in 1, 397 persons, and flexible colonoscopy in 187 persons. Colorectal cancers were detected in 18 patients (0.14 % of the total screened), ten of these cancers being in an early stage. Thus this screening method is reliable for detecting asymptomatic cancer of the colon and rectum.