A phase II trial of oral fluoropyrimidine anticancer agent (S-1) with concurrent external-beam radiotherapy for locally advanced pancreatic cancer

e15570 Background: S-1 is a new oral fluoropyrimidine anticancer agent and has shown a good efficacy for pancreatic cancer. In the phase I trial, we evaluated the safety of S-1 combined with external-beam radiotherapy (EBRT) to determine the maximum tolerated dose (MTD) and dose-limiting toxicity (DLT) in unresectable pancreatic cancer patients (H. Shinchi et al,, Br J Ca 2007;96:1353). The phase I trial determined the recommended of S-1 for the phase II chemoradiotherapy trial to be 80mg/m2/day given on days 1–21. This phase II trial was conducted to evaluate the efficacy and toxicity of EBRT combined with S-1 for locally advanced pancreatic cancer. Methods: Eligible patients had locally advanced and unresectable pancreatic cancer without distant metastases, ECOG PS 0–1, adequate organ and marrow function, and no prior anticancer therapy. EBRT was delivered in fractions of 1.25Gy twice daily, totaling 50Gy per 40 fractions for 4 weeks. S-1 was given orally at a dose of 80mg/m2/day twice a day on days 1–21. The primary end-point of this trial was objective tumor response and secondary end-points included toxicity and overall survival. Results: Forty patients were enrolled in this phase II trial. Of the 40 patients, 39 (97%) completed the scheduled course of chemoradiotherapy. The objective tumor responses by RECIST criteria included 13 PR (33%), 20 SD (50%) and 7 PD (17%). The median survival time was 14 months and 1-year survival rate was 67%. Although grade 3 rash and anorexia occurred in one patient each, no grade 4 toxicities were observed. Conclusions: Combination therapy of S-1 and radiation shows favorable efficacy for locally advanced pancreatic cancer and was well tolerated with no severe toxicities. No significant financial relationships to disclose.