4107 Background: Borderline resectable pancreatic cancer (BRPC) has a high probability of a positive surgical margin and poor prognosis because the tumor interacts with surrounding arteries or veins. Chemoradiotherapy (CRT) with S-1 has shown favorable activity in locally advanced pancreatic cancer. This study was designed to assess S-1 and concurrent radiotherapy in a neoadjuvant setting to determine whether it increases R0 resection rate for BRPC. Methods: This was a multicenter, single-arm phase II study. Patients with BRPC received S-1 (40 mg/m2 BID) and concurrent radiotherapy (50.4 Gy in 28 fractions) before surgery if they fulfilled any of the following: (1) bilateral impingement of superior mesenteric vein or portal vein; (2) tumor contact with superior mesenteric artery ≤180°; or (3) tumor contact with common hepatic artery or celiac axis ≤180°. Primary endpoint was R0 resection rate in BRPC confirmed by central review. At least 40 patients were required, with one-sided α = 0.05 and β = 0.05, with an expected and a threshold values for primary endpoint of 30% and 10%. Results: Fifty-two patients were eligible between December 2012 and May 2016. CRT was completed in 50 patients (96%) and was safe, with mostly grade 1 or 2 adverse events. Protocol treatment was withdrawn before surgery in 12 patients because of progressive disease diagnosed by computed tomography, and in one because of treatment refusal. Ten patients received exploratory laparotomy, or palliative/noncurative resection. In the rest of 29, R0 resection was conducted in 27, and R1 and RX in 1 patient each. This gave an R0 resection rate of 52% in all 52 eligible patients. In the 41 cases of BRPC confirmed by central review, R0 was confirmed in 26 (63%). Destruction of > 50% of tumor cells was confirmed pathologically in 10 (32%). Postoperative grade III/IV adverse events according to Clavien–Dindo classification were observed in 6 (15%). Conclusions: S-1 and concurrent radiotherapy were well tolerated and found to be effective in BRPC. A randomized controlled trial comparing neoadjuvant CRT and chemotherapy, including gemcitabine+nab-paclitaxel, for BRPC is under planning. Clinical trial information: NCT02459652.
Phase II trial of neoadjuvant S-1 and concurrent radiotherapy for borderline resectable pancreatic cancer (JASPAC05)
