Baseline fracture risk for prostate cancer patients initiating long-term androgen deprivation therapy.

122 Background: Androgen deprivation therapy (ADT) is essential for management of advanced prostate cancer, yet it carries risks including osteoporosis and fragility fractures. Antiresorptive therapy is recommended to reduce fractures for patients at high risk. However, precisely which patients should undergo formal screening with dual-energy X-ray absorptiometry (DEXA) at baseline has been relatively unexplored. This study aims to describe these baseline fracture risks, the utility of DEXA screening based upon Fracture Risk Assessment Tool (FRAX) scores, and the impact of specific risk factors in this population. Methods: We performed a retrospective cross-sectional study of patients at our institution with prostate cancer treated with ≥1 year of ADT between 2011 and 2024. Patients were excluded if their FRAX scores were incalculable or if they received antiresorptive therapy prior to starting ADT. Ten-year hip and combined major osteoporotic fracture risks were calculated using FRAX without femoral neck T-scores for all patients and with femoral neck T-scores for patients who received DEXA scans. A high fracture risk was defined as a 10-year hip fracture ≥3% or a combined major osteoporotic fracture risk ≥20%. Differences between dichotomous groups were assessed using independent samples t-tests, Chi-square tests, or Fisher’s exact tests. Results: We identified 515 patients with an average age of 70.1 years and average BMI of 29.5 kg/m 2 . Four hundred and forty-eight (87%) patients received leuprolide as ADT, 70 (13.6%) patients were on a prednisone-containing regimen, and 66 (12.8%) patients were active smokers. Based upon clinical data at ADT initiation (without including T-scores from DEXA), 201 (39.0%) patients had a high 10-year risk of hip or combined major osteoporotic fracture by FRAX. Among the 183 patients who did have DEXA scans, 85 (46.4%) met criteria for osteopenia while 14 (7.7%) had osteoporosis by T-score. Additionally, 48 (26.2%) patients had high 10-year fracture risks by FRAX and met criteria for initiation of antiresorptive therapy. The patients meeting criteria for antiresorptive therapy, in general, were older (73.3 years vs. 67.9 years) and weighed less (87.8 kilograms vs. 96.3 kilograms). Conclusions: In our institutional experience, nearly half of patients starting long term ADT have significant fracture risk warranting further risk stratification and risk mitigation strategies. This baseline data should inform systematic approaches to select those that do—and do not—require bisphosphonate or denosumab in the hormone sensitive setting.