A Prospective Phase II Trial of Neoadjuvant S-1 with Concurrent Hypofractionated Radiotherapy in Patients with Resectable and Borderline Resectable Pancreatic Ductal Adenocarcinoma

Background The ideal neoadjuvant treatment protocol for patients with pancreatic cancer (PDAC) remains unclear. We evaluated the efficacy and safety of neoadjuvant hypofractionated chemoradiotherapy with S-1 for patients with resectable (R) and borderline resectable (BR) PDAC. Methods Eligibility criteria included patients with R and BR PDAC, performance status 0–1, and age 20–85 years. Hypofractionated external-beam radiotherapy (30 Gy in 10 fractions) with concurrent S-1 (60 mg/m 2 ) was delivered 5 days/week for 2 weeks prior to pancreatectomy. Results Fifty-seven patients were enrolled in this study, including 33 R and 24 BR [19 BR tumors with portal vein contact (BR-PV) and 5 BR tumors with arterial contact (BR-A)]. The total rates of protocol treatment completion and resection were 91% (50/57) and 96% (55/57), respectively. Seven patients failed to complete S-1 due to cholangitis ( n = 5) or neutropenia ( n = 2). The most common grade 3 toxicities [Common Terminology Criteria for Adverse Events (CTCAE) version 4.0] were anorexia (7%), nausea (5%), neutropenia (4%), and leukopenia (4%). No patient experienced grade 4 toxicity. Pathologically negative margins (R0) were achieved in 54 of 55 patients (98%) who underwent pancreatectomy. Pathological response was classified as Evans grade I in 8 patients (15%), IIa in 31 patients (56%), IIb in 14 patients (25%), III in 1 patient (2%), and IV in 1 patient (2%), and operative morbidity (Clavien-Dindo grade IIIb or less) was observed in 4 patients (8%). The 1- and 2-year overall survival (OS) rates were 91 and 83% in R patients, respectively, and 77 and 58% in BR patients, respectively ( p = 0.03). Conclusion Neoadjuvant S-1 with concurrent hypofractionated radiotherapy is tolerable and appears promising for patients with R and BR PDAC.