Impact of a FIT Based Colorectal Cancer Screening Program on Gastric Cancer Incidence, Early Diagnosis and Patients' Survival.

[BACKGROUND AND AIMS] In countries with an intermediate incidence of gastric cancer (GC), it has been suggested that offering an upper gastrointestinal endoscopy (UGIE) to individuals referred for a screening colonoscopy following a positive result in the fecal immunochemical test (FIT) may be cost-effective. This study was designed to evaluate the impact of a FIT-based screening program on GC incidence, early diagnosis, and mortality.

[METHODS] Population-based retrospective cohort study in northern Portugal. Data on GC cases were retrieved from the Portuguese National Cancer Registry (RON). GC stage at diagnosis (with early stages defined as T1) and net survival estimates were compared between 2014 and 2016 and the first 3 years of the FIT-based screening program (2018-2020), during which 165,967 tests were performed.

[RESULTS] The odds of GC detection were significantly higher among FIT-positive individuals compared to those with a negative result (OR = 2.87; 95% CI: 1.76-4.49). Of the 10,372 individuals who completed FIT screening and underwent colonoscopy, 51% (n = 5281) also underwent UGIE. The proportion of early-stage diagnoses increased by 14% (95% CI: 12-15), and 3-year net survival improved from 42% (95% CI: 40-43) to 48% (95% CI: 47-50).

[DISCUSSION] Despite the absence of a formal GC screening program, more than half of FIT-screened individuals who underwent colonoscopy also underwent UGIE. The period following the implementation of FIT-based screening was associated with increased early-stage detection and improved survival. These findings support the potential value of offering UGIE combined with colonoscopy for FIT-positive individuals, at least in regions with intermediate GC incidence.