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. Patients 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 8 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, it was 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 S-1 plus cisplatin or docetaxel is an effective and tolerable option for patients with curatively resected stage III gastric cancer.