High-resolution peripheral quantitative computed tomography (HR-pQCT) to detect compartmental bone loss on androgen deprivation therapy (ADT): A feasibility study.

Abstract

209 Background: ADT causes bone loss, yet standard bone density (DXA) measurements do not distinguish cortical vs. trabecular bone loss and are falsely elevated in patients (pts) with sclerotic metastases, potentially underestimating fracture risk. HR-pQCT of the tibia and radius is a validated method to assess compartmental bone density and architecture that may overcome these limitations. Methods: Cross-sectional study of prostate cancer pts who underwent HR-pQCT (Scanco XtremeCT) of the radius and tibia and DXA scans within 6 months of initiating ADT. The relationship between HR-pQCT and relevant clinical variables was assessed using Spearman’s rank correlation method. Results: 22 pts were enrolled. Median baseline characteristics included: age = 64.5 (range 53-90), serum testosterone (T) level = 17 ng/dL (6-978), and interval between ADT start and HR-pQCT = 1.6 months (0-5.7). 5 pts (23%) were osteopenic as assessed by DXA. The correlation between HR-pQCT and clinical variables in shown in the Table. Of 12 pts with bone metastases, 7 (58%) had DXA L-spine and/or hip t-scores > 2 standard deviations above mean for 30 year-old male. In contrast, all 7 pts had HR-pQCT measurements within the expected range based on age, sex, and serum T. Conclusions: HR-pQCT to assess bone loss in prostate cancer pts on ADT is feasible. Radial trabecular bone volume and density are correlated with relevant clinical variables including ADT duration and serum T. In pts with bone metastases, HR-pQCT may provide more accurate means to estimate BMD and determine fracture risk. Longitudinal studies in pts on ADT with paired HR-pQCT scans are ongoing. Clinical trial information: NCT02168062. [Table: see text]