Phase angle as predictor of chemotherapy toxicity severity in breast cancer patients

Abstract

Introduction: Breast cancer is the leading cause of cancer-related mortality in Brazilian women. Chemotherapy, while effective, often induces debilitating side effects and toxicity. Phase angle (PA), derived from bioelectrical impedance, is a non-invasive biomarker associated with cellular health and prognosis. This study aimed to evaluate PA variation in breast cancer patients undergoing chemotherapy, correlating it with side effect severity, tumor molecular subtype, and patient age. Methods: An observational, longitudinal, retrospective study included 30 breast cancer patients treated with chemotherapy in Cascavel, PR, Brazil (2022-2023). PA was measured pre- and post-chemotherapy using a Sanny BIA1011-AF device. Side effects were graded (0-2 vs. 3-4) via CTCAE. Statistical analysis used t-tests, χ² test, and repeated measures ANOVA (p<0.05). Results: A significant PA reduction was noted from pre- to post-chemotherapy across the cohort (p<0.001). No main effect of age or molecular subtype on PA was observed. However, a significant interaction (p=0.017) between side effect grade and assessment time revealed that patients with grade 3-4 effects experienced a substantially greater PA decline (mean difference 0.8545 units; p<0.001). Conclusions: Chemotherapy for breast cancer leads to phase angle reduction. The magnitude of this reduction significantly correlated with side effect severity, independent of molecular subtype or age. PA is a sensitive indicator of chemotherapy's physiological impact and toxicity.