Impact of Organised Screening Program By Fecal Occult Blood Test on the Diagnosis Rate of Colorectal Adenomas: a Population-Based Study

Abstract

ABSTRACT Aim: Pilot colorectal cancer screening programs using a biennial fecal occult blood test (FOBT) started in France in 2003. A population-based Registry of adenomas, covering one of the pilot areas, gave the opportunity to describe time trends in the rate of diagnosis of colorectal adenomas, before and after the beginning of the screening program. Methods: The study relies on the only Registry which has been collecting since 1976 data on all cases of colorectal adenomas diagnosed in a well-defined administrative area (Cote-d'Or, France). This population-based study included all residents aged 50–74 years, with a first adenoma diagnosed between 01/1997 and 12/2008 and compared “pre- screening period” (1997-2002) with “post-screening period” (2003-2008). Standardized diagnosis rates were calculated by 5-year age group, gender and calendar year. Annual percentage changes were estimated using a Poisson regression model. Results: Over the study period, 4,908 men and 3,133 women were first-diagnosed with colorectal adenoma. High-risk adenomas (>1cm, villous component and/or high grade dysplasia) were found in 38.7% of them. For high-risk adenomas, age-standardized diagnosis rates were 136/100,000 before screening program and 257/100,000 after, with a percentage change of 89%. The corresponding rates for non-advanced adenomas were respectively: 235 and 392/100,000, with a percentage change of 68%. Data obtained on participation and positivity of tests for included individuals allowed to examine results according to these parameters. Conclusions: In actual conditions of clinical practice, we showed a marked increase in the rate of first adenoma diagnosis after 3 biennial colorectal cancer screening rounds, especially for high-risk adenomas. These results reinforce the interest of extending organized mass screening program. Using immunochemical FOBT, which showed better performance than guaiac-FOBT, will also improve results in the future. Disclosure: All authors have declared no conflicts of interest.