Longitudinal assessment of bone mineral density in prostate cancer patients: comparing metastatic and non-metastatic regions.

Objectives: Prostate cancer patients receiving androgen deprivation therapy (ADT) have increased risks of decreased bone mineral density (BMD). However, there are no established guidelines for assessing BMD in patients with bone metastases. The aim of this study was to assess the effects of ADT on bone health by comparing longitudinal changes in BMD between prostate cancer patients with and without bone metastases.

Methods: A single-center observational study was conducted from February 2020 to January 2023 at Kobe University Hospital. BMD at the lumbar vertebrae, total hip, and femoral neck was measured at baseline, 6, and 12 months using dual-energy X-ray absorptiometry. Bones were classified into Metastatic Site (with metastases), Non-metastatic Sites (from patients with bone metastases), and Control (patients without metastases) groups. All patients received luteinizing hormone-releasing hormone antagonists or agonists plus oral ARSI or bicalutamide for 1 year.

Results: Among the 78 patients, 35, 110, and 245 bones were classified into the Metastatic Site group, Non-metastatic Sites group, and Control group, respectively. The Metastatic Site group exhibited significantly higher T-scores compared with the other groups (P < 0.001). Repeated measures analysis revealed a statistically significant reduction in T-scores over time across all groups (P < 0.001). However, no significant interaction was observed between group classification and time (P = 0.817).

Conclusion: The present study demonstrates that BMD changes at non-metastatic sites in patients with bone metastases are similar to those in patients without metastases. Monitoring BMD at non-metastatic sites may provide valuable insights into ADT's effects on bone health in prostate cancer patients.