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.

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/m²) was delivered 5 days/week for 2 weeks prior to pancreatectomy.

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).

Neoadjuvant S-1 with concurrent hypofractionated radiotherapy is tolerable and appears promising for patients with R and BR PDAC.