Sarcopenia in Men With Bone-Predominant Metastatic Castration-Resistant Prostate Cancer Undergoing Ra-223 Therapy

Introduction Osteosarcopenia is the progressive loss of musculoskeletal structure and functionality, contributing to disability and mortality. Despite complex interactions between bone and muscle, osteosarcopenia prevention and treatment in men with metastatic castration-resistant prostate cancer (mCRPC) focuses predominantly on bone health. It is unknown whether Radium-223 (Ra-223) therapy affects sarcopenia. Methods We identified 52 patients with mCRPC who had received Ra-223 and had a baseline plus ≥1 follow-up abdominopelvic CT scan. The total contour area (TCA) and averaged Hounsfield units (HU) of the left and right psoas muscles were obtained at the inferior L3 endplate, and the Psoas Muscle Index (PMI) was calculated therefrom. Intra-patient musculoskeletal changes were analyzed across various time points. Results TCA and PMI gradually declined over the study period (p=0.002, p=0.003, respectively), but Ra-223 therapy did not accelerate sarcopenia, nor the decline of HU compared to the pre-Ra-223 period. The median overall survival of patients with baseline sarcopenia was numerically worse (14.93 versus 23.23 months, HR 0.612, p=0.198). Conclusions Ra-223 does not accelerate sarcopenia. Thus, worsening muscle parameters in men with mCRPC undergoing Ra-223 therapy are attributable to other factors. Further research is needed to determine whether baseline sarcopenia predicts poor overall survival in such patients. Micro-Abstract There are complex interactions between bone and skeletal muscle. However, the prevention and treatment of treatment-induced osteosarcopenia in men with metastatic castration-resistant prostate cancer focuses predominantly on bone health. In a single-center cohort of 52 patients we demonstrate that bone-targeted Radium-223 therapy does not accelerate sarcopenia, but baseline sarcopenia is associated with poor survival in such patients.