Introduction: Androgen-deprivation therapy (ADT) is standard of care for hormone-naïve metastatic prostate cancer (hnmPCa), often in combination with androgen receptor-axis-targeted therapies (ARAT).^[1] Decreased skeletal muscle mass (SMM) is a common side effect of ADT and is associated with adverse outcomes in cancer patients.^[2] Studies have investigated the impact of ADT on SMM;^[3] however few studies have investigated whether the addition of an ARAT to ADT worsens SMM decline. Herein, we investigated the impact of ADT alone, ADT with Abiraterone acetate and ADT with Enzalutamide on SMM.

Methods: This retrospective single-center chart review included hnmPCa patients treated with ADT alone, or in combination with Abiraterone acetate or Enzalutamide. The primary outcome was change in SMM as quantified on pre- and post-treatment CT images. The Skeletal Muscle Index (SMI) was calculated using a well-established method (Figure 1).^[4][5] Patients were defined as sarcopenic if SMI was <55cm²/kg² as per international consensus.^[2]

Results: 64 men with hormone-naïve metastatic prostate cancer were included in our study including 17 who were treated with ADT alone, 33 with ADT & Abiraterone and 14 with ADT & Enzalutamide. Pre-treatment baseline characteristics were not significantly different. The cohort’s mean follow-up time was 337 days, with no difference across groups. 75% of all men were found to be sarcopenic before the initiation of ADT. In addition, 37.5% of initially non-sarcopenic patients became sarcopenic during treatment. In terms of SMI, there was a 6% decline with ADT alone, a 4% decline with Abiraterone and a 6% decline with Enzalutamide (Table). These were not significantly different (p<0.05). Even when standardized per unit time, SMI decline was not significantly different across the groups.

Conclusions: This study highlights the significant impact of ADT on SMM in patients with hnmPCa. However, the addition of an ARAT to ADT did not impact the loss of SMM.