Psoas Muscle Volume Is a Predictive Marker of Fatigue and Anorexia in Prostate Cancer Patients Treated with Enzalutamide

Introduction: Enzalutamide is approved for the treatment of patients with metastatic castration-resistant prostate cancer. Adverse effects (e.g., fatigue and anorexia) are often observed and cause difficulty with continuous therapy; however, no clinical data describing which patients are more likely to suffer adverse effects were observed. Therefore, this study hypothesized that body composition, comprising body fat distribution and psoas muscle volume, may affect the occurrence of subjective symptoms (e.g., fatigue and anorexia) in prostate cancer patients treated with enzalutamide. Methods: Adverse effects, especially fatigue, anorexia, insomnia, and pain, were retrospectively evaluated by CTCAE v4.0 criteria. Sixty-seven prostate cancer patients treated with enzalutamide were enrolled, and body fat, visceral fat percentage, and psoas muscle ratio (psoas muscle, in cubic centimeter/height, in meters) were calculated using computed tomography images evaluated before enzalutamide, with SYNAPSE VINCENT software. Univariate analysis was performed to identify the factors associated with adverse effects. Conclusions: Psoas muscle ratio is a predictive marker of fatigue and anorexia in patients treated with enzalutamide.