Skeletal muscle depletion to predict survival of patients with advanced biliary tract cancer undergoing palliative chemotherapy.
460 Background: Reports regarding sarcopenia as a prognostic factor in advanced biliary tract cancer (BTC) are rare. Furthermore, no study has investigated the dynamics of body weight with body muscle mass as a prognostic factor in advanced BTC patients undergoing palliative chemotherapy. Hence, we investigated whether sarcopenia affects survival in patients with BTC, with a co-analysis of body weight loss and body mass index (BMI). Methods: We consecutively enrolled patients with advanced BTC who received palliative chemotherapy between 2003 and 2013. Total muscle cross-sectional area (cm2) at the L3 level assessed by computed tomography was analyzed. We defined sarcopenia as a skeletal muscle index (SMI) < 48.5 cm2/m2 (men) and < 39.5 cm2/m2(women) using ROC curves. Results: The proportion of patients with sarcopenia upon diagnosis was 52.4% and 42.2% for men and women, respectively. By multivariate analysis, sarcopenia 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 sarcopenic patients who were overweight or obese (BMI ≥ 25 kg/m2) 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). Conclusions: Sarcopenia, sarcopenic 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 prognosis of patients with BTC.