Biennial screening for colorectal cancer by testing for occult blood in stools. The experience of the French health fund’s health examination center

Aim: To assess biennial screening for colorectal cancer in health examination centers (CES) after four years of follow-up in complement to a preliminary publication. Method: We offered a biennial screening test for occult blood in stools (Hemoccult II ) by mail to patients who had had a negative screening test for occult blood two years pre-viously. Patients who had a positive result were then offered the possibility of undergoing further tests. Data on the actual outcomes were obtained from the attending physicians. We offered subsequent biennial screening only to patients who tested negative for occult blood. We enrolled a total of 121,127 patients who had taken part in a first screening test during a health examination (point n° 1). A second test was performed two years later in 1999-2000 in patients who tested negative in the first screening test (n° 2) and a third test in 2001-2002 for those who tested negative in the second screening test (n° 3). Results: The participation rate in the screening tests, compared to the number of subjects included in the initial screening sample, was 58.3 % after four years of follow-up. The participation rate increased from 81.6 % at point n° 2 to 91.7 % at point n° 3. A total of 3.01 % of the tests were positive. Data concerning follow-up from positives tests was available in 64.8 % of the cases. 1,014 patients were diagnosed with adenomas (positive predictive value = 20.2 %); 352 of the adenomas were larger than 10 mm. 276 cancers were detected (positive predictive value = 5.5 %). 53 % of the cancers were discovered following the initial screening test. Conclusion: These results are similar to our preliminary findings and suggest that biennial screening in examination centers is a satisfactory screening method after four years of follow-up with respect to clearly-defined quality criteria.