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

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.