S-1 Based Doublet As an Adjuvant Chemotherapy for Curatively Resected Stage III Gastric Cancer: Results from the Randomized Phase III POST Trial

Purpose: We conducted a randomized, multicenter, phase III trial to compare S-1 plus docetaxel (DS) with S-1 plus cisplatin (SP) as adjuvant chemotherapy for stage III gastric cancer patients.

Materials And Methods: Stage III gastric cancer patients who had received curative gastrectomy with D2 lymphadenectomy were randomized into equal groups to receive adjuvant chemotherapy of eight cycles of DS (S-1 70 mg/m2 /day on days 1-14 plus docetaxel 35 mg/m2 on days 1 and 8) every 3 weeks or SP (S-1 70 mg/m2 /day on days 1-14 plus cisplatin 60 mg/m2 on day 1) every 3 weeks. The primary endpoint was 3-year disease-free survival (DFS) rate.

Results: Between November 2010 and July 2013, 153 patients (75 patients to DS and 78 patients to SP) were enrolled from 8 institutions in Korea. After the capecitabine plus oxaliplatin was approved based on the CLASSIC study, itwas decided to close the study early. With a median follow-up duration of 56.9 months, the 3-year DFS rate between two groups was not significantly different (49.14% in DS group vs. 52.5% in SP group). The most common grade 3-4 adverse event was neutropenia (42.7% in DS and 38.5% in SP, p=0.351). SP group had more grade 3-4 anemia (1.3% vs. 11.5%, p=0.037), whereas grade 3-4 hand-foot syndrome (4.1% vs. 0%, p=0.025) and mucositis (10.7% vs. 2.6%, p=0.001) were more common in DS group. Fifty-one patients (68%) in DS group and 52 (66.7%) in SP group finished planned treatment.

Conclusion: Our findings suggest that SP or DS is an effective and tolerable option for patients with curatively resected stage III gastric cancer.