Colorectal Cancer Mortality after Colonoscopy: A Population-based Study: 2010 ACG Colorectal Cancer Prevention Abstract Award

Abstract

Purpose: There are limited data on mortality from colorectal cancer (CRC), after a colonoscopy. The objective of our study was to determine if there is a reduction in CRC mortality after colonoscopy in Manitoba, compared to the CRC mortality among the general population in Manitoba. Methods: We identified all individuals with a colonoscopy as their first lower gastrointestinal endoscopy between April 1, 1987 and September 30, 2007 from Manitoba's provincial physicians' billing claims database and followed them to March 31, 2008, death or out-migration from the province. Individuals less than 50 or greater than 80 years old at the index colonoscopy or with prior resective colorectal surgery or CRC or IBD were excluded. CRC mortality, after the index colonoscopy was compared to that in the general population by standardized mortality ratios (SMRs). Stratified analyses were performed to determine CRC mortality for different age groups at index colonoscopy, sex, duration of follow-up and site of CRC. Results: 54,803 individuals (24,342 men; 30,461 women) were followed-up for 310,718 person-years. There was a 29% reduction in overall CRC mortality [SMR 0.71;95% confidence interval (CI): 0.61-0.82], a 47% reduction in mortality from distal CRC (SMR 0.53;95% CI: 0.42-0.67) and no reduction in mortality from proximal CRC (SMR 0.94;95%CI: 0.77-1.17). The reduction in mortality from distal CRC remained significant for follow-up beyond 10 years. Conclusion: Colonoscopy in usual clinical practice can lead to a significant reduction in CRC mortality, but the benefit is not uniform for CRC occurring at different sites in the colon.