Efficacy of postoperative adjuvant chemotherapy using S-1 in elderly patients with resectable pancreatic cancer

Introduction: Although it has been reported that postoperative adjuvant chemotherapy using S-1 was dramatically improved the prognosis of pancreatic cancer, the efficacy of S-1 for the elderly patients is not clear. The aim of this study is to examine the clinical impact in elderly patients over 80 years old with resectable pancreatic cancer. Method: Total 159 patients underwent pancreatic resection for resectable pancreatic cancer between 2013 to 2017 in our department. Prior to the initiation of adjuvant chemotherapy, patients must fulfill the following criteria: (i) accomplishment of macroscopically curative resection with histologic R0 or R1 residual disease; (ii) Eastern Cooperative Oncology Group (ECOG) performance status of 0 or 1; (iii) adequate oral intake; (iv) without severe diarrhea; (v) without uncontrollable diabetes mellitus; and (vi) without liver or renal failure, and severe bone marrow suppression. We retrospectively compared treatment outcomes between 24 patients (15.1%) aged 80 years or older (elderly group) and 135 patients (84.9%) under age 80 (non-elderly group). Result: The patients who initiated adjuvant chemotherapy using S-1 were lower in the elderly group than in the non- elderly group (71 vs 92%; p=0.008). Ten patients (58%) in the elderly group and 94 patients (76%) in the non-elderly group (p=0.294) completed adjuvant chemotherapy using S-1. In all patients, 3-year survival rate of patients who completed adjuvant chemotherapy was longer than patients who did not complete (23.4 vs 73.6%; p<0.001). The patients who completed adjuvant chemotherapy both in elderly group and non-elderly group had no significant difference in postoperative prognosis (65.6 vs 74.6 %; P=0.508). Conclusion: Elderly patients can also improve their prognosis if adjuvant chemotherapy using S-1 is completed.