Purpose: 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.
Methods: 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).
Results: The median skeletal muscle and fat volumes among the patients were 93.3 cc (range 39.6-236.9) and 420.1 cc (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).
Conclusion: This study demonstrated that breast cancer patients with higher skeletal muscle volume showed more favorable prognosis.
Keywords: Breast cancer; Obesity; Prognosis; Skeletal muscle volume.