SCREENING FOR COLORECTAL NEOPLASIA WITH FECAL OCCULT BLOOD TESTING COMPARED WITH FLEXIBLE SIGMOIDOSCOPY DIRECTLY IN A 55-56 YEARS OLD POPULATION

Reduced mortality from colorectal cancer may be achieved by screening with faecal occult blood testing. Screening for neoplasia in the rectu m and sigmoid colon with flexible sigmoidoscopy is suggested to be mor e effective, particular among persons between 50 and 60 years of age. A cohort of 6367 persons 55-56 years of age were randomised to screeni ng with rehydrated Hemoccult II tests (HII group) or with flexible vid eosigmoidoscopy directly (FS group). In the HII group 59% (1893/3183) attended, compared to 49% (1353/3184) in the FS group. Of the 1893 per sons who attended in the HII group, 4% had a positive HII test and in 13% (10/78) of them a neoplasm greater than or equal to 1 cm in the re ctum or sigmoid colon was diagnosed by endoscopy. The corresponding ra te in the FS group was 2.3%. Overall the number of persons with a neop lasm greater than or equal to 1 cm diagnosed in the HII group was 10 a nd in the FS group 31. A subgroup in the flexible sigmoidoscopy group, who also performed rehydrated HII tests, showed a sensitivity of the HII test for neoplasia greater than or equal to 1 cm of 26% and a spec ificity of 95.6%. To find a neoplasm greater than or equal to 1 cm in the rectum or sigmoid colon, 44 examinations were needed when using fl exible sigmoidoscopy directly and 7 examinations when only those with positive HII tests were examined. In mass screening for neoplasia in t he rectum and sigmoid colon, the relatively low prevalence of colorect al neoplasia at 55-56 years of age makes primary selection with rehydr ated Hemoccult testing an alternative to the resource-consuming endosc opy of all invited persons.