Phase angle cutoff value as a marker of the health status and functional capacity in breast cancer survivors

Accurate predictive tools are key factors for cancer care. Phase angle (PhA) has been proposed as a marker of cellular health, particularly of cell-membrane integrity. Cutoff values have been proposed, including for cancer survivors. This study aimed to assess the usefulness of the proposed PhA cutoff, as a marker of bioelectrical impedance analysis (BIA) assessed health-status, and functional capacity in breast cancer (BC) survivors. This cross-sectional study included 25 women (50.6 ± 8.6 yrs) survivors of BC, divided into two groups according to the PhA reference value of 5.6° (group 1 [G1]: PhA ≤ 5.6° [n=13]; group 2 [G2]: PhA > 5.6° [n=12]) (Gupta et al. 2008). BIA-assessed health status parameters included: extracellular water (ECW), intracellular water (ICW), total body water (TBW), PhA, body mass, fat-free mass, muscle mass, body cell mass (BCM). Four functional tests were performed: 30 s chair-stand test, timed up and go test, ball throw test and 6-minute walking test. Results showed G2 had lower ECW/ICW ratio (p=0.001; ES=1.2), ECW/BCM ratio (p=0.001; ES=3.2) and ECW/TBW ratio (p=0.001; ES=4.8). There was no difference in functional capacity between groups. The results of the present study show that patients with higher PhA values have a higher ICW values and preservation in the ECW/ICW ratio, suggesting it's a better cell membrane quality and integrity. Relation of both PhA and cell membrane integrity with functional capacity warrants further research.