The optimal chemotherapeutic regimen in D2-resected locally advanced gastric cancer: a propensity score-matched analysis

Adjuvant chemotherapy using TS-1 or capecitabine plus oxaliplatin improves survival outcomes after radical gastrectomy, with both regimens showing similar efficacies. A total of 494 patients with stage II-III gastric cancer who underwent curative D2 gastrectomy and received adjuvant chemotherapy from April 2004 to June 2014 were included in this study. 219 patients received TS-1, and 275 received platinum-based chemotherapy. The disease-free survival associated with adjuvant chemotherapy with TS-1 was compared with that associated with fluoropyrimidine plus platinum chemotherapy to identify the subgroups that would benefit most from platinum-based chemotherapy. The platinum group consisted of younger individuals, more males and more stage III patients compared with the TS-1 group. To reduce selection bias and its effects on treatment results, we performed a propensity score-matched analysis. The matched cohort consisted of 219 TS-1 and 219 platinum treatment patients, respectively. In the matched cohort, the chemotherapeutic regimen did not affect disease-free survival according to stage (stage II: platinum vs. TS-1, P = 0.348; stage III: P = 0.132). According to the subgroup analysis, platinum-based chemotherapy resulted in an improved 3-year disease-free survival compared with TS-1 treatment (66.8% vs. 57.8%, P = 0.015) for patients with high-risk features (any two or more of pT4, pN3, and lymphovascular invasion positivity). Our results suggest that TS-1 alone is acceptable for patients without high-risk features, while platinum-based adjuvant chemotherapy should be administered to patients with high-risk features in D2-resected gastric cancer.