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

Post-treatment right psoas muscle Hounsfield unit (HU) and post-treatment VATI were independent prognostic factors for overall survival in mCRPC patients in multivariate analysis.

• Multivariate Cox regression identified post-treatment right PM HU as an independent prognostic factor (P = .02).
• Post-treatment VATI was an independent prognostic factor (P < .001).
• These two body composition parameters retained significance after adjusting for other covariates including age and treatment type.

Multiple body composition and clinical variables were significantly associated with mortality in univariate Cox regression analysis.

• Significant univariate associations with mortality included 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).
• Both pre- and post-treatment measurements of psoas muscle attenuation were prognostically relevant in univariate analysis.
• Changes in body composition parameters (ΔSATI and ΔVATI) were also significantly associated with mortality.

The study measured body composition using CT images at the L3 vertebral level in mCRPC patients treated between 2017 and 2022.

• The 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 cross-sectional areas of psoas muscle (PM), skeletal muscle (SM), visceral adipose tissue (VAT), and subcutaneous adipose tissue (SAT).
• Values were normalized by height (cm²/m²) to calculate indices: PMI, SMI, VATI, and SATI.
• Mean Hounsfield unit values of right and left PM were used to assess myosteatosis.
• Changes in body composition before and after treatment (ΔVATI, ΔSATI) were calculated to assess treatment-related changes.

Fat loss and increased myosteatosis during treatment may negatively affect prognosis in mCRPC patients.

• The authors highlight that fat loss (reflected in ΔVATI and ΔSATI changes) was associated with worse survival outcomes.
• Increased myosteatosis, assessed by lower PM HU values, was associated with worse overall survival.
• The findings underscore the importance of body composition monitoring during treatment for mCRPC.

Sarcopenia, assessed by baseline psoas muscle index (PMI), was associated with overall survival in univariate analysis.

• Baseline PMI was significantly associated with mortality in univariate Cox regression (P < .05).
• PMI was calculated as the cross-sectional area of the psoas muscle normalized by height squared (cm²/m²).
• Sarcopenia did not retain independent significance in multivariate analysis, where post-treatment VATI and right PM HU were the dominant factors.