SCREENING FOR COLORECTAL-CANCER WITH FECAL OCCULT BLOOD TESTING AND SIGMOIDOSCOPY

Background: The high incidence of and mortality from colorectal cancer (160000 new cases and 60000 deaths in the United States each year) ar e compelling public health concerns. Following the evolution of effect ive surgery for this disease since the 1960s, the focus has been on im proving methods of detection and integrating them into effective scree ning programs. Purpose: This was the first study to evaluate the effec tiveness, in a setting of comprehensive medical examinations, of using the fecal occult blood test in conjunction with sigmoidoscopy, rather than sigmoidoscopy alone, to screen for colorectal cancer. Our end po ints were extent of compliance with fecal occult blood test and sigmoi doscopy, numbers of cancers detected, and mortality rate. Methods: Fro m 1975 through 1979, a total of 21756 patients (aged 40 and older) who presented at the Preventive Medicine Institute-Strang Clinic for rout ine medical examinations were enrolled by calendar period into study a nd control groups. Study patients were offered annually both rigid sig moidoscopy examinations and fecal occult blood tests requiring two sto ol specimens per day for 3 days, while control patients were offered o nly annual sigmoidoscopy. The majority of fecal occult blood test card s were not rehydrated before assay. Patients with positive tests were referred for double-contrast barium enema and colonoscopy. Two distinc t trials were carried out. Trial I was primarily a demonstration of fe asibility of using the fecal occult blood test as a supplemental scree ning method. Of the 9277 participants, 7168 (77%) were assigned to the study group and offered the fecal occult blood test. In trial II, app roximately half of the 12479 patients were assigned to each group. Pat ients in both trials had follow-up through 1984. Results: Compliance w ith the fecal occult blood test was initially high in both trials, but diminished such that only 56% of study patients in trial I and 20% of those in trial II returned for second tests. On the initial (prevalen ce) screen, a substantial number of early-stage cancers were detected by the fecal occult blood test, primarily in trial II. In trial II, su rvival probability was significantly greater (P<.001) in the study gro up than in the controls (70% versus 48%), and colorectal cancer mortal ity was lower (0.36 versus 0.63) with borderline significance (P = .05 3, one-sided). Conclusions and Implications: The screening of average- risk individuals (aged 50 and older) for colorectal cancer through use of the fecal occult blood test in conjunction with sigmoidoscopy can increase the likelihood of early detection of this disease. This pract ice, coupled with prompt diagnostic work-up following positive tests, will result in treatment of earlier stage cancers and increased surviv al after treatment.