Declining Cost-Effectiveness of Gastric Cancer Screening Over a Decade: A Cohort Modelling Study

Background & Aim: The cost-utility of a mature cancer screening programme can shift as disease incidence, costs, and population risk change. We examined how these changes affected Korea’s National Cancer Screening Program (NCSP) for gastric cancer by comparing two hypothetical cohorts parameterized with 2012 and 2022 conditions. Methods: Two structurally identical state-transition models simulated biennial endoscopic screening versus no organised screening in adults aged 40-79 years over a lifetime horizon, incorporating period-specific screen-detected health-state distributions, effective screening sensitivity, NCSP participation, and treatment costs. Incremental cost-utility ratios (ICURs) per quality-adjusted life-years (QALYs) were calculated in period-specific prices. For cross-period comparison, incremental costs were converted to 2025 KRW, and net monetary benefit (NMB) was calculated at a willingness-to-pay threshold of KRW 50 million/QALY(USD 40,000). Results: The ICUR increased from KRW 9.62 million/QALY(USD 7,694) in the 2012 model to KRW 48.62 million/QALY(USD 38,895) in the 2022 model, and NMB in 2025 KRW decreased from KRW 1.73 million to KRW −0.05 million per person. In 2022, the ICUR was KRW 28.20 million/QALY(USD 22,558) for men and KRW 84.37 million/QALY(USD 67,497) for women. The increase was driven mainly by a shift in the screen-detected histologic composition of neoplasia toward lower-risk non-adenomatous findings and by higher costs. Conclusions: The cost-effectiveness of uniform biennial endoscopic screening in Korea declined substantially between 2012 and 2022 and the 2022 results were markedly less favourable for women than for men. These findings support periodic reassessment of mature screening programmes and further evaluation of differentiated screening approaches.