Association of phase angle with muscle function and prognosis in patients with head and neck cancer undergoing chemoradiotherapy

Objective: We aimed to investigate the correlation of phase angle (PhA) with other parameters (e.g., muscle mass/quality/strength and physical function), assess the prognostic relevance of pre-chemoradiotherapy (CRT) PhA, and suggest a reference value of PhA in Asian patients with head and neck cancer (HNC).
Research Methods & Procedures: Ninety-six patients with HNC who underwent CRT were divided into two groups, maintained-PhA group and low-PhA group, according to the PhA 25th percentile values by sex. Pretreatment PhA was measured using direct segmental multi-frequency bioelectrical impedance analysis, and muscle quality was assessed using echo intensity in ultrasound images. Correlation of PhA with other parameters was investigated, and between-group differences with respect to adverse events, treatment interruption, and 3-year survival were assessed.
Results: PhA showed a positive correlation with isometric knee extension force (R = 0.710), handgrip strength (R = 0.649), skeletal muscle mass index (R = 0.620), and maximum gait speed (R = 0.543) (P < 0.001). PhA showed a negative correlation with echo intensity (R = −0.439) and five times sit-to-stand test (R = −0.505) (P < 0.01). The low-PhA group had a higher incidence of severe anemia (52% in low-PhA vs. 17% in maintained-PhA), aspiration (17% vs. 1%), radiotherapy interruption (17% vs. 3%), and poor 3-year survival (47% vs. 81%) than the maintained-PhA group (P < 0.05).
Conclusion: PhA was correlated with muscle mass/quality/strength, and physical function. Low PhA was associated with severe adverse events, treatment interruption, and shorter survival. These findings suggested that 4.6° for men and 4.0° for women may be useful as prognostic reference values in Asian patients with HNC.

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