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.