Comparison of adjuvant capecitabine plus oxaliplatin (CAPOX) versus S-1 after gastrectomy: a population-based cohort study using a nationwide claims database

Although 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. We 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. A total of 6602 patients were included in the analysis, with 4199 in Arm S and 2403 in Arm C. After propensity score matching, the final study population consisted of 2067 patients in each arm. Arm C showed statistically inferior 5-year overall survival (OS) and disease-free survival (DFS) rates compared to Arm S (84.0% vs. 90.0%; p