Effectiveness and Safety of Colorectal Cancer Screening Via Fecal Occult Blood Testing: A Systematic Review and Meta-Analysis.

PURPOSE: This systematic review evaluated the effectiveness of population-based colorectal cancer (CRC) screening programs using fecal occult blood tests (gFOBT or FIT) among adults aged 45-75 years. METHODS: We included studies comparing participants in population-based CRC screening programs with unscreened individuals. Outcomes were all-cause mortality, CRC-specific mortality, CRC incidence, and stage IV CRC incidence. Two reviewers independently performed study selection, data extraction, and risk-of-bias assessment. Pooled RRs were calculated by meta-analysis, and certainty of evidence was assessed using GRADE. RESULTS: No difference was observed in all-cause mortality (RR = 1.00, 95% CI 0.99-1.01; 5 studies, 1,474,576 participants; moderate-certainty evidence). RCTs evaluating gFOBT demonstrated a reduction in CRC-specific mortality (RR = 0.89, 95% CI 0.84-0.94; 5 studies, 1,474,576 participants; moderate-certainty evidence), corresponding to 38 fewer CRC deaths per 100,000 individuals screened (95% CI, 55 fewer to 21 fewer). Non-RCTs evaluating FIT reported larger reductions in CRC-specific mortality (RR = 0.21, 95% CI 0.20-0.21; 5 studies, 7,435,956 participants), although the certainty of evidence was low. RCTs showed no significant effect on CRC incidence or stage IV CRC incidence, whereas non-RCTs evaluating FIT suggested reductions in both outcomes; however, the certainty of evidence was also low. CONCLUSION: Fecal occult blood test-based screening reduces CRC-specific mortality but not all-cause mortality. FIT-based screening may provide additional benefits by reducing CRC incidence and stage IV disease; however, these findings are supported by low-certainty evidence and require confirmation in RCTs.