Sarcopenia as a Potential Risk Factor for Denosumab-Related Osteonecrosis of the Jaw in Asian Prostate Cancer Patients with Bone Metastases.

Background/Objectives: Denosumab-related osteonecrosis of the jaw (DRONJ) is a serious complication in patients receiving long-term antiresorptive therapy for bone metastases from prostate cancer. While established risk factors include invasive dental procedures and poor oral health, the role of body composition, with a particular focus on sarcopenia and inflammatory biomarkers, remains unclear. This study aims to evaluate the association between skeletal muscle mass, fat distribution, and systemic inflammatory biomarkers with DRONJ risk in Asian prostate cancer patients with bone metastases. Methods: This retrospective study reviewed 64 patients who received denosumab between 2014 and 2023. Baseline CT scans were used to measure total psoas muscle index (TPI), visceral fat area (VFA), subcutaneous fat area (SFA), and body mass index (BMI). Neutrophil-to-lymphocyte ratio (NLR) and platelet-to-lymphocyte ratio (PLR) were calculated from blood counts. Group comparisons used the Wilcoxon rank-sum or chi-squared test, and correlations were assessed using Spearman's coefficient. Results: Twelve patients (18.8%) developed DRONJ, with a mean onset time of 20.3 months. The prevalence of sarcopenia was significantly higher in the DRONJ group compared to the non-DRONJ group (p = 0.0331). VFA, SFA, BMI, diabetes, and visceral obesity were not significant predictors. NLR, but not PLR, showed a significant negative correlation with TPI (ρ = -0.2487, p = 0.0475), but no direct association with DRONJ, suggesting an indirect effect via sarcopenia. Conclusions: Sarcopenia may be an independent risk factor for DRONJ. Inflammatory biomarkers, particularly NLR, may contribute indirectly through reduced muscle mass. Body composition assessment may improve DRONJ risk stratification.