Abstract
The efficacy of fecal occult blood testing (FOBT) and flexible sigmoidoscopy (FS) for colorectal cancer (CRC) screening has been well documented but the efficacy of FOBT in combination with FS has not yet been established. Since 1983, we have been conducting community-based mass screening for CRC using FOBT in combination with FS in Kyushu, Japan. In 1988, we designed special buses with the necessary equipment to perform FS screening to test as many people as possible. The 2-day fecal immunochemical test (FIT) for FOBT has been in use since 1992. During the 32-year period from 1983 to 2014, 1,952,565 subjects underwent FOBT, and among these FOBT subjects, 319,418 underwent FS. We investigated the utility and efficacy of combining FOBT with FS, based on the results of the present mass screening for CRC. First, 2-day FIT combined with FS can detect CRC nearly twice as effectively as 2-day FIT alone. In particular, this method is effective and recommended in first-time examinees. Second, the sensitivity and specificity of the combination of 2-day FIT and FS followed-up at 2 years for invasive cancer were 91% and 83%, respectively. In contrast, those of the 2-day FIT alone were 79% and 93%, respectively. Third, we conducted a population-based case-control study to evaluate the efficacy of the combination of FOBT with FS. In subjects with a history of FOBT in combination with FS, even when corrected for screening using FOBT alone, compared with those without a history of screening, the risk of CRC mortality was reduced by approximately 50% for colon cancer in general and by approximately 70% for rectal cancer and sigmoid colon cancer. These findings suggest that the combination of FOBT and FS screening may reduce the mortality rate of CRC. Although there are some problems with introducing FS for mass screening for CRC, (i.e. cost-effectiveness, speed of examinations, and lack of manpower), a combination with FS is expected to prevail because of ease of preparation and a shorter and safer procedure than colonoscopy.
