Skeletal muscle depletion predicts survival of patients with advanced biliary tract cancer undergoing palliative chemotherapy

BACKGROUND: No prior study has investigated the dynamics of body weight with body muscle mass as a prognostic factor in advanced biliary tract cancer (BTC) patients undergoing palliative chemotherapy. We investigated whether low skeletal muscle mass affects survival in patients with BTC, with a co-analysis of body weight loss and body mass index (BMI). RESULTS: By multivariate analysis, low skeletal muscle mass at diagnosis and decreased SMI during chemotherapy (p = 0.008 and p < 0.001, respectively) were poor prognostic factors for overall survival (OS). Subgroup analysis revealed that low skeletal muscle mass patients who were overweight or obese (BMI ≥ 25 kg/m(2)) showed worse OS (p < 0.001). Additionally, patients with both decreased BMI and SMI during chemotherapy had worse OS (p < 0.001). Furthermore, patients with decreased SMI had shorter survival regardless of change in BMI. However, for patients with SMI maintained during chemotherapy, decreased BMI had no effect on survival (p = 0.576). MATERIALS AND METHODS: We consecutively enrolled 524 patients with advanced BTC who received palliative chemotherapy between 2003 and 2013. Total muscle cross-sectional area (cm(2)) at the L3 level assessed by computed tomography was analyzed. We defined low skeletal muscle mass as a skeletal muscle index (SMI) < 48.5 cm(2)/m(2) (men) and < 39.5 cm(2)/m(2) (women) using ROC curves. CONCLUSIONS: Low skeletal muscle mass, obesity and muscle depletion during palliative chemotherapy are meaningful prognostic factors in advanced BTC. Considering muscle depletion with weight change could help to more accurately predict prognoses of patients with BTC.