Efficacy of head and neck computed tomography for skeletal muscle mass estimation in patients with head and neck cancer

Diminished skeletal muscle mass (SMM) is a reliable marker of poor survival outcomes in patients with cancer. SMM or body composition is generally assessed at the third lumbar vertebra (L3) by abdominal computed tomography (CT) scans, not routinely evaluated in patients with head and neck squamous cell carcinoma (HNSCC). Therefore, we evaluated the effectiveness of head and neck CT images to assess SMM in patients with HNSCC for predicting their overall survival. SMM was assessed in 305 consecutive patients with stage III–IV HNSCC by measuring the cross-sectional area (CSA) at the third lumbar and cervical (C3) vertebrae levels. A formula for predicting the L3 SMM was established using linear regression analysis obtained from C3 CSA and other clinical factors. The actual SMM CSAs measured at L3 level and those obtained from the prediction model were compared using correlation analysis. The predictive power of our formula for estimating overall survival was compared using C-index. Median SMM CSAs at the L3 and C3 levels were 174.5 cm2 and 56.3 cm2, respectively, and were not strongly correlated (adjusted R2 = 0.421). Prediction model 2 included the strongest predictive factors including sex, age, weight, and C3 SMM CSA, and significantly increased the L3 SMM correlation power (adjusted R2 = 0.721). The C-index of the prediction model was 0.713 (95% confidence interval 0.692–0.747). Head and neck CT imaging might be useful to estimate L3 SMM and predict overall survival in HNSCC patients.