Comparison of S-1 and cisplatin combination versus S-1 adjuvant chemotherapy for advanced gastric cancer.

Abstract

e14652 Background: Adjuvant chemotherapy demonstrated the efficacy for stage II-III gastric cancer patients in the ACT-GC and CLASSIC trial. However, in the subgroup analysis, stage III patients receiving S-1 monotherapy didn’t report survival benefit unlike the capecitabine/oxaliplatin combination regimen in CLASSIC trial. With the assumption that doublet adjuvant chemotherapy may be more effective for advanced stages of patients, we compared the efficacy of S-1/cisplatin (SP) and S-1 adjuvant chemotherapy. Methods: After curative D2 resection, 274 patients were treated with S-1 monotherapy (98 patients, 80 mg/m2 for 4 weeks, every 6 weeks) or S-1 plus cisplatin (176 patients, S-1 80 mg/m2 day 1-14 and cisplatin 60 mg/m2 day 1, every 3 weeks). Treatment was continued for 12 months in S-1 arm and 6 months in SP arm or until unacceptable toxic effects or disease progression. Results: A total of 65 (66.3%) patients in SP and 118 (67%) in S-1 group completed all the treatment. The relative dose intensity of S-1 was 82% for S-1 and 88% for SP group, respectively. During the early times after the operation, more patients in SP group completed adjuvant treatment. More patients in SP discontinued treatment during the 1st cycle (12.5% S-1 vs 8.5 % SP group) and this trend was consisted thereafter. The progression free survival (PFS) was not reached for both groups. For the stage III patients, 2 year PFS was better for SP group (89%) than S-1 group (80.8%). Among the 23 recurrence, S-1 group (19.8%) demonstrated more frequent recurrence than SP group (12%). In terms of tolerance, hematologic toxicities was more frequent in SP group, therefore, 21% of SP group and 3.4% of S-1 monotherapy had grade 3-4 neutropenia. However, for the non-hematologic toxicity, grade 3-4 anorexia was similar and grade 3-4 stomatitis was more common in S-1 group (2.8% vs 7%) Conclusions: S-1 plus cisplatin adjuvant chemotherapy is effective and tolerable. For the high risk patients, considering favorable compliance and slightly better efficacy, combination treatment may be a good therapeutic option. Further studies for optimal drugs and schedule are warranted.