Colonoscopy versus biennial FIT screening: a post hoc sustained-strategy analysis of the COLONPREV Trial

Background Pragmatic colorectal cancer (CRC) screening trials compare colonoscopy with faecal immunochemical testing (FIT), but differences in adherence complicate interpretation of comparative outcomes. Objective To compare 10-year risks of CRC mortality, CRC incidence and all-cause mortality under one-time colonoscopy versus sustained FIT strategies in the COLONPREV Trial. Design We conducted a post hoc per-protocol analysis of 17 270 screening initiators aged 50–69 years in eight Spanish regions, using inverse probability weighting to adjust for observed confounding and informative protocol deviations. Results Weighted 10-year risks were similar for CRC incidence (0.80% FIT vs 0.86% colonoscopy; risk difference (RD) 0.06%, 95% CI −0.25% to 0.37%) and all-cause mortality (4.02% vs 4.09%; RD 0.07%, 95% CI −0.76% to 0.84%). CRC mortality was lower with colonoscopy (0.072% FIT vs 0.042% colonoscopy; RD −0.03%, 95% CI −0.12% to 0.06%), but estimates were imprecise. Conclusion Sustained colonoscopy and FIT showed similar 10-year outcomes overall, highlighting the importance of adherence pathways in pragmatic screening trials. Trial registration number ClinicalTrials.gov: NCT00906997 .