Prognostic impact of skeletal muscle volume derived from cross-sectional computed tomography images in breast cancer.

Abstract

This study aimed to determine whether the prognosis of breast cancer is affected by muscle or fat volume as measured from computed tomography (CT) images. We identified 1460 patients with chest CT who were diagnosed as having breast cancer at the National Cancer Center, Korea, between January 2001 and December 2009. Using CT images of 10-mm slices, we measured the cross-sectional areas of skeletal muscle and adipose tissue at the 3rd lumbar vertebrae, and derived their volumes. The skeletal muscle volume, fat volume, and muscle-to-fat ratio were evaluated for association with overall survival (OS) and recurrence-free survival (RFS). The median skeletal muscle and fat volumes among the patients were 93.3cc (range 39.6-236.9) and 420.1cc (range 19.5-1392.3), respectively. Patients with higher muscle volume had better prognosis than those with lower muscle volume [hazard ratio (HR) 0.56, 95% confidence interval (CI) 0.34-0.92, P = 0.022 for OS; HR 0.72, 95% CI 0.52-0.99, P = 0.046 for RFS]. However, body mass index (BMI) and fat volume were not associated with prognosis. In addition, muscle volume was a significant prognosticator for OS, regardless of BMI (HR 0.55, 95% CI 0.32-0.93, P = 0.034 in BMI < 25.0; HR 0.44, 95% CI 0.21-0.91, P = 0.026 in BMI ≥ 25.0). Among older patients (≥ 50), those with higher muscle volume showed better OS and RFS (HR 0.44, 95% CI 0.23-0.85, P = 0.015; HR 0.55, 95% CI 0.34-0.90, P = 0.017, respectively). This study demonstrated that breast cancer patients with higher skeletal muscle volume showed more favorable prognosis.