Prospective cohort study of colorectal cancer risk with negative colonoscopy or nonadherence after positive FOBT screening

A prospective cohort study in the Stockholm-Gotland region (Sweden) evaluated the incidence of colorectal cancer (CRC) after a negative screening colonoscopy result or nonadherence to colonoscopy in individuals with a positive fecal occult blood test (FOBT) result. The study cohort included all men and women born between 1938 and 1954 residing in the region between 2008 and 2012 who were invited to a CRC screening. Individuals with a positive FOBT result were categorized as (1) having a negative result on recommended follow-up colonoscopy or (2) nonadherence to recommended follow-up colonoscopy. The primary outcome was CRC incidence compared with the general population (defined as all individuals in the cohort who were invited to screening, excluding those with negative colonoscopy or nonadherence following positive FOBT). Among 14,873 individuals with a positive FOBT, those with a negative screening colonoscopy result had a significantly lower observed CRC incidence (SIR 0.52; 95% CI 0.39-0.68) compared to the general population, whereas individuals with a positive FOBT who did not adhere to follow-up colonoscopy had a markedly increased CRC incidence (4.21; 3.24-5.48) compared to the general population. The authors conclude that these findings support risk-based follow-up strategies in CRC screening programs and highlight a high-risk group that may benefit from targeted interventions to improve early tumor detection.