S-1 vs. Gemcitabine as an Adjuvant Therapy after Surgical Resection for Ductal Adenocarcinoma of the Pancreas

Background Pancreatectomy with regional lymphadenectomy remains the only curative treatment option for pancreatic cancer. There is no clear consensus on what type of adjuvant therapy should be used for patients with pancreatic cancer. Objective Our objective was to retrospectively evaluate whether postoperative adjuvant chemotherapy using S-1 is clinically beneficial in managing resectable pancreatic cancer. Methods Patients were divided into three groups: those undergoing surgery alone, those receiving gemcitabine infusion, and those receiving S-1 orally. Results Of 189 studied patients, the median overall survival was 15.0 months after surgery alone, 33.0 months in the gemcitabine group, and 45.0 months in patients receiving S-1. A multivariate analysis identified regional lymph node metastasis, positive surgical margins, and absence of adjuvant chemotherapy as independent negative prognostic factors. S-1 was not inferior to gemcitabine in terms of survival outcomes and showed a favorable hazard ratio compared with gemcitabine in the subsets of patients with positive vascular invasion. Conclusions There was no difference between adjuvant chemotherapy with S-1 and gemcitabine in overall survival for patients with curative pancreatic cancer. Our results suggested that S-1 can be used as a second agent to gemcitabine after surgical resection for ordinary adenocarcinoma of the pancreas.