A randomized phase III trial of postoperative adjuvant therapy with S-1 alone versus S-1 plus PSK for stage II/IIIA gastric cancer: Hokuriku-Kinki Immunochemo-Therapy Study Group-Gastric Cancer (HKIT-GC).

In this randomized multicenter Phase III study, patients with curatively resected Stage II/IIIA gastric cancer were assigned to postoperative adjuvant therapy with an oral fluoropyrimidine S-1 alone (2 weeks of treatment and 1 week of rest for 6 months, followed by 2 weeks of treatment and 2 weeks of rest for 6 months) or S-1 combined with an oral biological response modifier PSK (the same regimen of S-1 plus daily PSK for 12 months). The main objective was to evaluate the survival benefit and quality of life (QOL) of combined therapy. The primary end points were the time to relapse and the duration of survival after surgery, i.e. the rates of disease-free survival and overall survival at 3 and 5 years. The secondary end points were the relations of survival rates to drug compliance, QOL, adverse events, postoperative complications, relapse status, and the preoperative expression of immune or tumor markers. The sample size was 140 per treatment arm.