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Objectives: The aim of this population-based study was to specify the positivity rate, the positive predictive value of Hemoccult test as well as the characteristics of the cancers and adenomas screened during the successive colorectal cancer screening campaigns., Methods: This study focused on five colorectal cancer mass screening campaigns by Hemoccult test carried out between 1988 and 1996. The test was offered every two years to a cohort of subjects born between 1914 and 1943 and living in some districts of the Saône-et-Loire administrative area., Results: The positivity rate of the test was higher in the first campaign (2.1%) than in the subsequent ones (mean 1.3%). It was also higher in males than in females and it increased with age. After a positive test, 85.4% of the subjects had a colonic exploration. The exploration rate was higher when the test was offered by general practitioners (88.0%) than when it was mailed (77.8%) (P < 0.01). Through this test, cancer was detected in 168 patients, and one adenoma or more in 414 patients. The positive predictive value was 11.4% for cancer, 17.1% for adenoma > or = 1 cm and 11.1 for adenoma < 1 cm. It was higher in males than in females and it increased with age. Depending on the campaigns, 35.9% to 47.3% of the subjects explored after a positive test had a cancer or an adenoma. The screened cancers or adenomas were more often localized in the sigmoid or the rectum. Three quarters of screened cancers were stage I or II (TNM classification). All together, 82.7% of cancers were treated with surgical resection for cure and 10.1% with endoscopic resection., Conclusions: This work confirms the feasibility of carrying out regular colorectal cancer screening campaigns, through which a few subjects can be selected for undergoing colonic explorations. These latter can detect a cancer or adenoma in 40% of cases.

Our aim was to study the relationship between the level of positivity of the Hemoccult colorectal cancer screening test and the positive predictive value on one hand, and the characteristics of the screened neoplasms on the other. This study focuses on four successive colorectal cancer screening campaigns in a population of 45,642 subjects born between 1914 and 1943. There were 1 or 2 positive slides in 50.1% of cases, 3 or 4 in 30.7% of cases and 5 or 6 in 19.2% of cases. The positive predictive value was 11.1% for cancer, 17.4% for adenoma > or = at 1 cm and 10.1% for adenoma < 1 cm. For a cancer or adenoma > or = at 1 cm, the positive predictive value varied between 18.6% when there were 1 or 2 positive slides, and 52.5% when there were 5 or 6 positive slides. Dukes A cancers are less likely to have 5 or 6 positive slides than more advanced cancers. On the contrary, neither cancer localisation nor characteristics of adenomas > or = at 1 cm (localisation, size, degree of dysplasia) influenced the number of positive slides. Owing to intermittent colorectal cancer bleeding, it seems necessary to take several successive samples. Two samples per stool over three successive stools seem like a good compromise. The informative value of the test increases with the number of positive slides.