Randomized phase II study of S-1 monotherapy versus gemcitabine plus S-1 in gemcitabine-refractory advanced pancreatic cancer.

429Background: Gemcitabine is one of the standard chemotherapeutic agents for pancreatic cancer in a first-line setting. In a second-line setting, there are various unmet needs. After gemcitabine chemotherapy, S-1 is mainly used and sometimes gemcitabine plus S-1 (GS) is used. Cytotoxic effect of gemcitabine had been reported to have the potential to be enhanced when used with fluorouracil. This randomized study aimed to evaluate the efficacy and safety of gemcitabine plus S-1 in gemcitabine-refractory advanced pancreatic cancer. Methods: This phase II study consisted of patients (pts) who were randomly allocated into the GS group (gemcitabine 1,000 mg/m2 on days 1 and 8 plus S-1 60, 80, or 100 mg/d according to body-surface area on days 1 through 14 of a 21-day cycle) or the S-1 group (S-1 80, 100, or 120 mg/d according to body-surface area on days 1 through 28 of a 42-day cycle) at a 1:1 ratio. The primary endpoint was the evaluation of progression-free survival (PFS). The sample size of 90 pts was chos...