Association of Fat and Muscle Mass With Overall Survival in Patients With Metastatic Prostate Cancer Treated With Enzalutamide, Abiraterone, and Docetaxel.

[OBJECTIVE] To investigate the association between fat and muscle mass parameters and overall survival in patients with castration-resistant metastatic prostate cancer (mCRPC) receiving chemotherapy or androgen deprivation therapy.

[MATERIALS AND METHODS] This retrospective study included mCRPC patients treated with docetaxel, abiraterone, or enzalutamide between January 01, 2017 and December 31, 2022. CT images at the L3 vertebral level were used to measure the cross-sectional areas of psoas muscle (PM), skeletal muscle (SM), visceral adipose tissue (VAT), and subcutaneous adipose tissue (SAT). These values were normalized by height (cm²/m²) to calculate indices (PMI, SMI, VATI, SATI). Mean hounsfield unit (HU) values of right and left PM were used to assess myosteatosis. Changes in body composition before and after treatment (eg, ΔVATI, ΔSATI) were also calculated. Survival analysis was performed using (ROC) receiver operating curves and Kaplan-Meier tests.

[RESULTS] Univariate Cox regression showed significant associations between mortality and age, treatment type, right PM HU (pre and post-treatment), left PM HU (post-treatment), post-treatment VATI, ΔSATI, ΔVATI, and baseline PMI (P < .05 for all). In multivariate analysis, post-treatment right PM HU and VATI were independent prognostic factors (P = .02 and P < .001, respectively).

[CONCLUSION] Fat mass, sarcopenia, and myosteatosis-especially post-treatment VATI and right PM attenuation-were associated with survival in mCRPC. Fat loss and increased myosteatosis may negatively affect prognosis, highlighting the importance of body composition monitoring during treatment.