[A study on the complementary scheme of mass screening for colorectal cancer in an asymptomatic population]

Both SPA immunological fecal occult blood test (SPA FOBT test) and detection of T-antigen in rectal mucus (Shams' test) were used as screening tests in asymptomatic mass screening to evaluate the complementary effect of both tests for detection of colorectal cancers. SPA FOBT test showed a positive rate of 11.1% and shams' test 8.9% among 7,740 subjects. In 498 cases with positive screening test, 11 cases of carcinomas and 88 adenomas were found with colonoscopy. Only 9 cancers and 55 adenomas showed positive result in SPA FOBT test and 8 cancers and 51 adenomas in Shams' test. Both tests combined could enhance the detective rate of cancer in asymptomatic mass screening from 81.8% with SPA FOBT test or 72.7% with Shams' test to 90.9%. This complementary effect was more obvious in adenoma detection. It is suggested that there were some shortcomings in sequential FOBT test for cancer detection, the combined use of the two different screening tests for detection of colorectal cancer could decrease the rate of missed detection.