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 1–2...