Randomized phase II trial of chemoradiotherapy with S‐1 versus combination chemotherapy with gemcitabine and S‐1 as neoadjuvant treatment for resectable pancreatic cancer (JASPAC 04)

Abstract Objective The aim of the present study was to investigate which treatment, neoadjuvant chemoradiotherapy (NAC‐RT) with S‐1 or combination neoadjuvant chemotherapy with gemcitabine and S‐1 (NAC‐GS), is more promising as neoadjuvant treatment (NAT) for resectable pancreatic cancer in terms of effectiveness and safety. Methods In the NAC‐RT with S‐1 group, the patients received a total radiation dose of 50.4 Gy in 28 fractions with oral S‐1. In the NAC‐GS group, the patients received intravenous gemcitabine at a dose of 1000 mg/m 2 with oral S‐1 for two cycles. The primary endpoint was the 2‐year progression‐free survival (PFS) rate. The trial was registered with the UMIN Clinical Trial Registry as UMIN000014894. Results From April 2014 to April 2017, a total of 103 patients were enrolled. After exclusion of one patient because of ineligibility, 51 patients were included in the NAC‐RT with S‐1 group, and 51 patients were included in the NAC‐GS group in the intention‐to‐treat analysis. The 2‐year PFS rate was 45.0% (90% confidence interval [CI]: 33.3%–56.0%) in the NAC‐RT with S‐1 group and 54.9% (42.8%–65.5%) in the NAC‐GS group ( p = .350). The 2‐year overall survival rate was 66.7% in the NAC‐RT with S‐1 group and 72.4% in the NAC‐GS group ( p = .300). Although leukopenia and neutropenia rates were significantly higher in the NAC‐GS group than in the NAC‐RT with S‐1 group ( p = .023 and p < .001), other adverse events of NAT and postoperative complications were comparable between the two groups. Conclusion Both NAC‐RT with S‐1 and NAC‐GS are considered promising treatments for resectable pancreatic cancer.