Clinical Outcomes of Capecitabine-based Versus S-1-based Regimens As First-line Chemotherapy in Patients with Unresectable or Metastatic Gastric Cancer: a Propensity Score Matched Single-center Comparison

Background: Fluoropyrimidine-based regimens are the cornerstone of first-line chemotherapy for metastatic gastric cancer (GC). Capecitabine or S-1 might be used as an alternative to infusional 5-fluorouracil, especially in pan-Asian. This study aimed to compare the clinical outcomes of capecitabine-based and S-1-based regimens as first-line chemotherapy in Chinese patients with unresectable or metastatic GC.

Methods: We conducted a retrospective study including unresectable or metastatic GC patients treated with the capecitabine-based or S-1-based regimen as first-line chemotherapy at the First Hospital of China Medical University. Propensity score matching (PSM) analysis was performed to reduce selection bias. Overall survival (OS) outcomes were compared using the Kaplan-Meier method and log-rank test. Prognostic significance was determined using multivariate Cox regression analysis. In addition, subgroup analyses were conducted to determine the effectiveness of capecitabine-based and S-1-based regimens in clinically relevant patient subsets.

Results: The clinical data of 469 patients included between October 2005 and September 2018. PSM analysis identified 187 patients receiving capecitabine-based or S-1-based regimen. No significant difference in OS (10.7 11.1 months, P=0.523) was detected between the two groups after PSM. In the subgroup analysis, the median OS (12.2 9.3 months, P=0.013) was longer for patients with peritoneum metastasis who received the capecitabine-based regimen compared to those who received the S-1-based regimen.

Conclusions: No significant difference in clinical outcomes was observed between the capecitabine and S-1-based regimen as first-line chemotherapy for metastatic or unresectable GC patients in China. The capecitabine-based regimen should be considered in the treatment of the GC patients with peritoneum metastasis.