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).

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 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.