[Randomized phase II trial to compare S-1 and S-1/PSK for advanced or recurrent gastric cancer-lessons from the results].

Abstract This is a randomized phase II trial to evaluate non-inferiority of progression-free surviva(l PFS) by comparing S-1 and S-1/PSK for advanced or recurrent gastric cancer. Sample size was calculated to be 120. However, the trial was terminated because of slow accrual. This exploratory analysis was done by collecting the minimum data. Only 8 patients were enrolled. Four patients were randomly assigned to S-1 and the others to S-1/PSK. Performance status was 0 in all 8 patients. Median age was 64. Median overall survival was 13.7 months in all 8 patients, 8 . 9 months in S-1 group, and 13 . 7 months in S-1/PSK group. When considering PS 0 in 8 patients enrolled, an overall survival was comparable to that observed in S-1 group of other phase III trials. Standard chemotherapy for advanced gastric cancer was changed to S-1/CDDP by SPIRITS phase III trial which was presented just after this trial was initiated, which would be a major cause of slow accrual. When conducting phase III trial, we should carefully determine design and standard arm by considering on-going phase III trial.