Combination chemotherapy of S-1 and low-dose twice-weekly cisplatin for advanced and recurrent gastric cancer in an outpatient setting: a retrospective study.

BACKGROUND

We have reported the efficacy and safety of S-1 combined with low-dose consecutive cisplatin therapy for advanced and recurrent gastric cancer, but the regimen was difficult because daily cisplatin administration was necessary. We have already confirmed that cisplatin of 6 mg/m2 twice-weekly maintained the same protein-bound Pt concentration as that of 3 mg/m2 of cisplatin daily. In the present study, the efficacy and safety of a combination of S-1 and low-dose twice-weekly cisplatin were investigated.

PATIENTS AND METHODS

The participants were 32 patients treated at our hospital, and all were admitted for the first 2 weeks of therapy. S-1 at 80 mg/m2 daily was administered orally in two divided doses. Cisplatin at 6 mg/m2 was administered by intravenous drip infusion over 30 minutes on 2 days each week, day 1 and day 4. Each treatment cycle consisted of 4 weeks of drug administration followed by a 2-week drug-free period (6 weeks in total).

RESULTS

A total of 146 cycles were administered, with a median of three cycles (range: 1-24) per patient. The results were rated as a complete response in 1 case, partial response in 24 cases and stable disease in 5 cases. The response rate was 78.1% (25/32) and the median survival time was 12.0 months (95% confidence interval (CI) 8.9-15.1 months). The response rate did not differ between previously treated and untreated patients. The one-year survival rate was 48.2% (95% CI 30.3-66.0%). The major adverse reactions were myelosuppression and gastrointestinal symptoms. The total incidence of grade 3 or greater adverse reactions was 15.6% (5/32).

CONCLUSION

The combination of S-1 and low-dose twice-weekly cisplatin therapy appears to be highly efficacious and safe and shows promise as a useful treatment strategy, even in outpatient clinics.