Bioelectrical impedance analysis as a quantitative measure of sarcopenia in head and neck cancer patients treated with radiotherapy.

BACKGROUND AND PURPOSE: Sarcopenia is associated with decreased survival in head and neck cancer patients treated with radiotherapy. This study sought to determine whether in-clinic multifrequency bioelectrical impedance analysis (BIA) can identify survival-associated sarcopenia in patients with head and neck cancer. MATERIALS AND METHODS: This prospective observational study enrolled 50 patients with head and neck cancer undergoing radiation therapy. Baseline BIA measures of skeletal muscle (SM) mass, fat-free mass (FFM), and fat mass (FM) were compared to CT-based estimates using linear regression. Sex-specific BIA-derived thresholds for sarcopenia were defined by the maximum Youden Index on receiver operator characteristic (ROC) curves. Patients were stratified by sarcopenia status and OS was compared using the Kaplan-Meier method and log-rank test. RESULTS: Among 48 evaluable patients, BIA measures of body composition were strongly correlated with CT measures: SM mass (r = 0.97; R2 = 0.94; p < 0.0001), FFM (r = 0.97; R2 = 0.94; p < 0.0001) and FM (r = 0.95; R2 = 0.90; p < 0.0001). SM mass index < 9.19 kg/m2 identified sarcopenia men with high sensitivity (91.7%) and specificity (92.9%), whereas in women SM mass index < 6.53 kg/m2 was sensitive for sarcopenia (100%), but not specific. Patients with sarcopenia, defined by either CT or BIA, exhibited decreased OS (HR = not estimable; CT p = 0.009; BIA p = 0.03). CONCLUSION: BIA provides accurate estimates of body composition in head and neck cancer patients. Implementation of BIA in clinical practice may identify patients with sarcopenia at risk for poor survival.