Phase Angle as a prognostic factor of survival in patients with metastatic prostate cancer.

Background & aims: Phase angle (PA), derived from bioelectrical impedance analysis (BIA), is a non-invasive marker of cellular integrity and nutritional status. While its prognostic value has been demonstrated in various malignancies, evidence in metastatic prostate cancer (mPCa) is scarce. This study aimed to evaluate the association between PA and overall survival (OS) in patients with mPCa receiving androgen deprivation therapy (ADT).

Methods: We conducted a retrospective cohort study including 103 patients with confirmed mPCa undergoing ADT. PA was measured using multi-frequency BIA and patients were categorized into two groups: PA ≤ 4.0° and PA > 4.0°. Clinical, anthropometric, and body composition data were collected. OS was estimated using Kaplan-Meier analysis, and Cox proportional hazards models were used to assess the association between PA and mortality.

Results: Patients with PA ≤ 4.0° (n = 24; 23.3%) had significantly lower fat-free mass and higher fat mass percentage compared to those with PA > 4.0° (n = 79; 76.7%). A significantly higher proportion of patients with PA ≤ 4.0° experienced disease progression (79.2% vs. 45.6%, p = 0.004). Kaplan-Meier analysis showed reduced survival in the low PA group (Log-rank p = 0.0043). In multivariate Cox regression, PA ≤ 4.0° was independently associated with higher mortality risk (HR: 4.603; 95% CI: 1.653-12.817; p = 0.003).

Conclusions: Low phase angle is independently associated with reduced survival in men with mPCa undergoing ADT. PA may serve as a reliable, low-cost biomarker for risk stratification and nutritional assessment in this population.