Skeletal Muscle Loss and Octogenarian Status Are Associated with S-1 Adjuvant Therapy Discontinuation and Poor Prognosis after Pancreatectomy

SIMPLE SUMMARY: Significant advances in surgical techniques and perioperative care, together with adjuvant chemotherapy, have contributed to the increasing number of patients with pancreatic cancer undergoing surgery. However, the results of some studies suggest that the postoperative complications and mortality might be higher in elderly patients undergoing pancreatectomy. We aimed to identify the utility of S-1 adjuvant chemotherapy in elderly patients with resected pancreatic cancer. In our cohort of 80 patients, including 16 octogenarians, univariate and multivariate analyses revealed that S-1 adjuvant chemotherapy was associated with improved prognosis in patients with pancreatic cancer. However, we also observed that skeletal muscle loss and age of 80 years or older predicted the failure to complete adjuvant chemotherapy with S-1. We propose that evaluation of skeletal muscle mass should be considered as a useful preoperative assessment approach for determining feasibility of adjuvant chemotherapy in elderly patients. ABSTRACT: The efficacy and prognosis of adjuvant chemotherapy for resected pancreatic cancer remain unclear. We investigated the utility and risk factors of S-1 adjuvant chemotherapy in patients with pancreatic cancer undergoing pancreatectomy. This study comprised 80 patients, including 58 patients who received S-1 adjuvant chemotherapy. Skeletal muscle loss was defined using cutoff values of skeletal muscle mass index. In total, 16 (20%) octogenarian patients underwent pancreatectomy. Skeletal muscle loss was present in 56 (70%) patients. The entire course of S-1 adjuvant chemotherapy for 6 months was completed in 33 patients (41%). S-1 adjuvant chemotherapy <6 months was an independent prognostic indicator of poor overall survival. Patients who completed S-1 adjuvant chemotherapy exhibited significantly longer overall and relapse-free survival rates than those did not complete the chemotherapy (p < 0.0001 and p = 0.0003, respectively). Being an octogenarian and skeletal muscle loss were independent variables associated with the discontinuation of S-1 adjuvant chemotherapy. Finally, the S-1 adjuvant chemotherapy rates were 6.3% (1/16) and 28.6% (16/56) in octogenarian patients and those with skeletal muscle loss, respectively. S-1 adjuvant chemotherapy completion was associated with improved prognosis in patients with pancreatic cancer. Skeletal muscle loss and octogenarian status predicted the failure of S-1 adjuvant chemotherapy completion.