Colorectal cancer screening through detection of fecal occult blood in a controlled health zone.

Aim: to determine the viability and utility of fecal occult blood (FOB) screening (Hemoccult II) as a method for the early diagnosis of colorectal cancer in a well-controlled health area.

Methods: between February 1994 and September 1996, personal letters were sent to all persons in the Casas Ibáñez health area (Albacete) aged between 50 and 75 years (4986 persons). All the tests were read by the same team member. A clinical history was taken of persons with positive test results, and they were offered colonoscopy. If a growth was found which was suitable for endoscopic resection, this was done. If the growth was totally resected an annual check-up was advised. Malignant and partially resected premalignant growths were referred for surgical treatment. We analyzed percent participation, attendance for testing, negative and positive tests, growths diagnosed, false-positive tests and positive predictive value.

Results: the a participation rate was 56.25%. In the 157 colonoscopies performed, 39 neoplasic polyps and 9 cancers were found (7 of which were Dukes stage A and 2 of which were Dukes stage C-D). Sensitivity was 97% and specificity was 96%. The positive predictive value was 30.37%. The positivity rate was 6.08%, while the predictive value for cancer was 5.38% and the predictive value for adenoma was 23.35%.

Conclusions: FOB screening, in our setting, proved to have a high recruitment capacity with a positive predictive value for colorectal carcinoma which was slightly higher than the value obtained in other countries of similar socioeconomic status. Furthermore, we found a significant improvement in the diagnostic stage of colorectal carcinoma at the time of resection.