Giulio Antonelli1, Jessica Battagello2, Manuel Zorzi2, Cesare Hassan1

1Digestive Endoscopy Unit, Nuovo Regina Margherita Hospital, Rome, Italy, 2Veneto Tumor Registry, Azienda Zero, Padova , Italy

Background/Aims: Adenoma Detection Rate (ADR) is the most important quality measure in colonoscopy and has been associated to a reduced Colorectal Cancer (CRC) incidence and mortality in the primary and opportunistic colonoscopy settings. No evidence has been reported about organised FIT-based CRC screening programs, which are widely used in the Western community. Our aim was to evaluate the association between ADR and CRC incidence and mortality in a FIT-based screening program.

Methods: We retrieved data from a cohort of patients undergoing colonoscopy after a FIT+ within a CRC screening program based on biannual FIT in a region of Italy (Veneto) between 2003 and 2017, and estimated the risk of post-colonoscopy (interval) CRC by the Regional Cancer Registry. To assess the association between endoscopists

Results: Overall, we included 68,604 colonoscopies performed by 133 endoscopists. ADR ranged from 15 to 67%. During follow-up, 289 CRCs and 42 CRC related deaths were recorded. When subdividing endoscopists by ADR quintile, the unadjusted risk of CRC from lowest-to highest quintile was 11.4, 9.7, 7.6, 11.4 and 9.5 per 10,000 person/years of follow up. As compared to the lowest ADR quintile, the adjusted hazard ratio for CRC related death in the 2nd,3rd,4th and 5th quintile was 0.39 [95%CI 0.13-1.19], 0.70 [95%CI 0.27-1.79], 0.87 [95%CI 0.36-2.14], 0.56 [95%CI 0.19-1.62], respectively.

Conclusion: In a long-standing population CRC screening program based on the FIT, ADR was not associated to the risk of CRC incidence and mortality.

Keywords: Screening, Colonoscopy, FIT, Colorectal Cancer, Adenoma Detection Rate