Long-term outcome of S-1 and cisplatin combination therapy in patients with advanced or recurrent gastric cancer

Background Although combination therapy of S-1 and cisplatin (CDDP) has excellent efficacy against gastric cancer, the effect of the treatment on survival has been unclear. The aim of this study was to evaluate the long-term outcome of this combination therapy.Methods Sixty-three patients with advanced or recurrent gastric cancer were treated with S-1, with or without CDDP, as first-line chemotherapy, and the clinical results were compared retrospectively. S-1 was administered orally at a standard dose of 80mg/m². In the treatment of the S-1 group, S-1 was given for 28 consecutive days, followed by a 14-day rest. In the treatment of the S-1/CDDP group, S-1 was given for 21 consecutive days, followed by a 14-day rest, and CDDP, at 60mg/m², was infused on day 8.Results The incidence of adverse reactions of more than grade 3 was 22.5% in the S-1 group and 43.5% in the S-1/CDDP group, and the treatment compliance was better in the S-1 group. The overall response rate was 25.9% in the S-1 group, and 36.8% in the S-1/CDDP group. The combination of S-1 with CDDP had better effects on the primary lesion and on differentiated-type carcinoma than S-1 alone. However, there was no difference in survival between the two patient groups. The median survival time after the initiation of treatment in the S-1 group was 322 days, and that in the S-1/CDDP group was 319 days.Conclusions Our results suggest that the combination of CDDP with S-1 does not improve the long-term outcome of S-1 therapy.