Colorectal Cancer Prevention by CLEAR Principles-based Colonoscopy Protocol: An Observational Study

Abstract Background and Aims Colorectal cancer (CRC) prevention by colonoscopy has been lower than expected. We studied CRC prevention outcomes of a colonoscopy protocol based on CLEAR principles, an acronym for: (1) Clean the colon, (2) Look Everywhere, and (3) complete Abnormality Removal. Methods Observational follow-up study of patients provided screening colonoscopy at a free-standing private ambulatory surgery center in South Carolina by 80 endoscopists from October 2001 to December 2014, followed through December 2015. The colonoscopy protocol, optimized for polyp clearance, featured (1) in-person bowel preparation instructions reinforced by phone; (2) polyp search and removal throughout insertion and gradual withdrawal with circumferential tip movements, and (3) team approach using all personnel present to maximize polyp detection, patient safety, and clear-margin polypectomy including requesting repeat inspection or additional tissue removal. Outcome measures were postscreening lifetime CRC risk relative to SEER-18 and interval cancer rate (postcolonoscopy CRCs among cancer-free patients at screening) Results Of 25,862 patients (mean age 58.1 years, 52% black, 205,522 person-years, PYO), 159 had CRC at screening and 67 patients developed interval CRC. Interval CRC rate was 3.34/10,000 PYO, 5.79 and 2.24 among patients with and without adenomas, respectively. The rate was similar among older patients (mean 68.5 years at screening) and with prolonged follow-up. Postscreening lifetime CRC risk was 1.6% (bootstrap 95% confidence interval, 1.3% - 1.8%), versus 4.7% in SEER-18, 67% lower. Subgroups with mean screening age 50 and 68.5 years showed risk reductions of 80% and 72%, respectively. Adverse event rate was less than usually reported rates: perforation 2.6/10,000, bleeding with hospitalization 2.4/10,000, and no deaths. Conclusions A colonoscopy protocol optimized for polyp clearance prevented 67% of CRC compared with SEER-18 population given ongoing population screening.