CRC Risk Diverges After Positive FOBT Based on Colonoscopy Follow-Up

Individuals with a positive fecal occult blood test (FOBT) have markedly different colorectal cancer (CRC) risk depending on whether they complete follow-up colonoscopy, according to a large prospective cohort study from a population-based screening program in Sweden. The findings support risk-based follow-up strategies and highlight nonadherence as a key target for intervention.

The study included 318,096 adults aged 60 to 69 years invited to biennial FOBT screening between 2008 and 2012. Among 14,873 individuals with a positive FOBT result, 87.3% underwent colonoscopy, of which 73.5% were negative. CRC incidence was compared with the broader screened population using standardized incidence ratios (SIRs).

Individuals with a negative colonoscopy after a positive FOBT had a significantly lower CRC incidence than the general screening population (SIR, 0.52). The reduction was more pronounced in men (SIR, 0.37) than in women (SIR, 0.71).

In contrast, individuals who did not undergo recommended colonoscopy after a positive FOBT had a substantially higher CRC risk (SIR, 4.21). This group represents a clinically important population with missed opportunities for early detection and intervention.

The authors reported that “a decrease in CRC incidence was observed among individuals with negative results in screening colonoscopies,” while “a high-risk group for CRC was identified among individuals who did not adhere to follow-up colonoscopy.” These divergent outcomes underscore the importance of complete diagnostic evaluation after a positive screening test.

Reference
Heyman H, Saraste D, Jonsson H, Blom J. Colorectal cancer risk with negative colonoscopy or nonadherence after positive FOBT screening. JAMA Netw Open. 2026;9(3):e262404. doi:10.1001/jamanetworkopen.2026.2404