Comparison of adjuvant capecitabine plus oxaliplatin (CAPOX) versus S-1 in patients with gastric cancer after gastrectomy: A nationwide cohort study based on the National Health Insurance Service (NHIS) database in Korea

AbstractBackgroundAlthough both capecitabine plus oxaliplatin (CAPOX) and S-1 are accepted as adjuvant chemotherapy following gastrectomy for gastric cancer, the better option between the two is still controversial.MethodsWe conducted a retrospective nationwide cohort study using data from the National Health Insurance Service of Korea. We included patients who underwent gastrectomy for a primary diagnosis of gastric cancer between January 1, 2013, and December 31, 2018. The study compared the survival outcomes of patients who received postoperative chemotherapy based on S-1 (Arm S) vs. CAPOX (Arm C), as well as other relevant clinical variables such as comorbidity and completion of planned treatment.ResultsA total of 6,602 patients were included in the analysis, with 4,199 in Arm S and 2,403 in Arm C. After propensity score matching, the final study population consisted of 2,067 patients in each arm. Arm C showed statistically inferior five-year overall survival (OS) and disease-free survival (DFS) rates compared to Arm S (84.0% vs. 90.0%; p < 0.0001; and 78.4% vs. 86.1%; p < 0.0001). Age (65 ≥ vs. <65) and the incomplete planned treatment also had a significant negative effect on both OS and DFS. In the multivariable analysis, Arm C still showed worse OS (hazard ratio [HR], 1.609; 95% confidence intervals [CI], 1.339–1.934; p < 0.0001) and DFS (HR, 1.552; 95% CI, 1.333–1.807; p < 0.0001) than Arm S.ConclusionBoth S-1 and CAPOX showed excellent efficacy, but this nationwide cohort study suggests that S-1 may be a better option in certain clinical situations.