Reduction of Colorectal Cancer Mortality and Advanced Stage Cancer Incidence After 10 Years of Fecal Immunochemical Test Screening

Abstract

Background and aims: Colorectal cancer (CRC) is a leading cause of cancer deaths worldwide, and fecal immunochemical testing (FIT) is most widely used for population-based screening. Reduced long-term CRC mortality has been reported only scarcely in response to early detection with FIT screening. We aimed to elucidate whether and how FIT screening led to overall and site-specific reduction of advanced stage CRC incidence and mortality after the first decade of Taiwan's screening program, which offers biennial FIT screening for people aged 50-69 years. Method: The study cohort comprised eligible subjects who did (screened group) and did not (unscreened group) participate in FIT screening during the inaugural 5 years (2004-2009) with follow up until 2014. FIT-positive subjects were offered colonoscopy as a confirmatory exam. The primary outcome was incidence of advanced stage CRC and CRC mortality. Results: Among 5,417,699 eligible subjects, 3,072,164 (56.6%) had at least once FIT screening, and 1,605,200 (52.3%) received 2 or more screenings during the study period. During mean follow-up of 9.78 years, 5716 screened and 20,962 unscreened subjects developed incident advanced stage cancers [adjusted relative risk (aRR) = 0.76; 95% CI, 0.72-0.79] after controlling for self-selection to attend screening and increasing CRC incidence. CRC deaths during follow-up included 3077 screened and 15,550 unscreened subjects (aRR = 0.56, 95% CI, 0.53-0.59). Effectiveness was greater for distal cancers (advanced cancer incidence aRR = 0.68, 95% CI, 0.65-0.71); mortality aRR = 0.52 95% CI, 0.49-0.55) than for proximal cancers (advanced cancer incidence aRR = 0.99 95% CI, 0.92-1.07; mortality aRR = 0.69 95% CI, 0.63-0.75). Conclusion: FIT screening effectively reduces risk of advanced stage CRC and CRC mortality, with effectiveness consistently stronger for distal CRC than proximal CRC.