S-1 Versus S-1 Plus Cisplatin As First-line Treatment for Metastatic Gastric Cancer

Objective: To compare S-1 with S-1 plus cisplatin (SP) as first-line treatment for metastatic gastric cancer. Methods: Records of patients with metastatic gastric cancer who received either the S-1 or SP regimen as first-line treatment for metastatic gastric cancer between January 2013 and December 2014 in Queen Mary Hospital were retrospectively reviewed. Baseline characteristics, overall response rate, median progression-free survival (PFS), overall survival (OS), and toxicity of the two groups were compared. Results: During the study period, 17 patients received S-1 and 13 patients received SP. The median patient ages were 69 and 57 years, respectively. In the S-1 group, more patients were aged >= 70 years (47.1% vs. 7.7%, p = 0.02), fewer patients underwent surgical resection of primary tumours (23.5% vs. 53.8%, p = 0.09), more patients required initial dose reduction (70.6% vs. 15.4%, p = 0.001), and fewer patients received subsequent chemotherapy (5.9% vs. 30.8%, p = 0.07) compared with the SP group. The S-1 group had a lower response rate (11.8% vs. 46.2%, p = 0.049). Nonetheless, S-1 and SP groups were comparable for clinical benefit rate (47.1% vs. 77.0%, p = 0.14), median PFS (34.5 weeks vs. 28.8 weeks, p = 0.72), median OS (46.4 weeks vs. 52.7 weeks, p = 0.18), and 30-day mortality (11.8% vs. 7.7%, p = 1.00). There was a trend of improved OS in the SP group (hazard ratio = 1.84, 95% confidence interval = 0.74-4.55, p = 0.185). The two groups were also comparable for the rate of grade 3/4 neutropaenia (17.7% vs. 38.5%, p = 0.24) and grade 3/4 diarrhoea (5.9% vs. 30.8%, p = 0.14). There was no treatment-related death. Conclusion: Both S-1 and SP regimens are effective and safe as first-line treatment for metastatic gastric cancer. A dose-adjusted S-1 regimen is a viable option for patients with advanced age and marginal performance status.