Effects of psoas major muscle volume in predicting the prognosis of patients with upper urinary tract urothelial carcinoma treated with radical nephroureterectomy.

BACKGROUND This study evaluated the impact of sarcopenia and psoas major muscle volume on the survival of patients with upper urinary tract urothelial carcinoma who had undergone radical nephroureterectomy. METHODS We reviewed data from 110 patients treated with radical nephroureterectomy in our department between June 2007 and February 2017. Psoas major muscle volume was quantified based on computed tomography data using Synapse Vincent software. The psoas major muscle volume index was calculated as psoas major muscle volume/height squared (cm3/m2). We analysed relapse-free survival, cancer-specific survival and overall survival after radical nephroureterectomy to identify factors that predicted patient survival. RESULTS The median psoas major muscle volume index was 121.5 cm3/m2, and the psoas major muscle volume index was <100 cm3/m2 in 34 of 110 patients (30.9%). Multivariate analysis indicated that ≥pT3-stage cancer, lymphovascular invasion and a psoas major muscle volume index of <100 cm3/m2 were independent predictors of shorter relapse-free survival, cancer-specific survival and overall survival. Using these factors, patients were stratified into three groups: low, intermediate and high risks for relapse-free survival, cancer-specific survival and overall survival. CONCLUSIONS Low psoas major muscle volume resulting from sarcopenia, high T stage and the presence of lymphovascular invasion was associated with poor survival in patients with urinary tract urothelial carcinoma who had undergone radical nephroureterectomy, supporting the use of psoas major muscle volume as a new objective prognostic marker.