Retrospective study of gemcitabine plus S-1 versus gemcitabine alone in cases with unresectable advanced pancreatic cancer.

Background: The aim of this study was to compare gemcitabine plus S-1 (GS) combination chemotherapy to gemcitabine (GEM) monotherapy in cases with unresectable advanced pancreatic cancer. Methods: We retrospectively reviewed 107 consecutive patients with unresectable advanced pancreatic cancer who received GEM monotherapy or GS combination chemotherapy between 2004 and 2010. In 73 patients, GEM (1000 mg/m(2)) was administered intravenously on days 1, 8 and 15, repeated every four weeks. The GS regimen received by 34 patients consisted of intravenous GEM (1000 mg/m(2)) on days 1 and 8, combined with oral S-1 (40 mg/m(2)) twice daily on days 1-14, repeated every four weeks. Results: Response rates in the GEM and GS groups (6.8% versus 32.4%) varied significantly, as did disease control rates (28.8% versus 61.8%, respectively). There was a significant difference in median overall survival (206 versus 258 days) and median progression-free survival (86 versus 123 days) between the GEM and GS groups. Grade 3/4 toxicities in both groups were neutropenia (16.4% in GEM, 17.6% in GS), thrombocytopenia (1.3%, 2.9%), anorexia (1.3%, 0%), and diarrhea (1.3%, 0%). Conclusions: Retrospectively, GS combination therapy is feasible more effective than GEM monotherapy, and therefore should be considered in cases with unresectable advanced pancreatic cancer.