Central and peripheral areal BMD, bone microarchitecture, and strength after initiation of androgen deprivation therapy in men with prostate cancer: a two-year follow-up study.

INTRODUCTION: Androgen Deprivation Therapy (ADT) in prostate cancer (PCa) is associated with bone loss and increased fracture risk. Previous studies on the effects of ADT on bone have focused on areal bone mineral density (aBMD) from dual-energy X-ray absorptiometry (DXA) at the central skeleton, while the effects on peripheral aBMD, bone microarchitecture, and bone strength are less well studied. METHODS: In this two-year observational study, we examined the changes in aBMD and volumetric BMD, bone area, microarchitecture, and strength from high-resolution peripheral quantitative CT (HR-pQCT) after ADT initiation in men with PCa. RESULTS: A total of 115 men were included, of whom 43 were treated with zoledronic acid (ZOL+) from ADT initiation and the other 72 were not (ZOL -), according to national guidelines. DXA (lumbar spine, total hip, femoral neck, total body, left and right arm, left and right leg) and HR-pQCT (distal radius, distal tibia) measurements were performed at ADT initiation (T0) and after 24 months (T2). aBMD in the ZOL- group significantly decreased between T0 and T2 at all measurement locations (p < 0.05), with a mean decrease ranging between -3.0 ± 7.4% (left leg) and -5.0 ± 5.1% (femoral neck). In the ZOL+ group, only lumbar spine and right leg aBMD significantly changed (+3.6 ± 4.3% and -2.3 ± 3.2%, respectively). Using HR-pQCT, it was found that bone area, volumetric BMD, microarchitecture, and strength significantly declined at the distal radius and tibia in both the ZOL - and ZOL+ group. The most significant changes were noted at the distal radius in cortical area (ZOL-: -10.1 ± 5.9%; ZOL+: -6.5 ± 5.1%), total BMD (ZOL-: -8.8 ± 4.2%; ZOL+: -5.5 ± 3.7%), and failure load (ZOL-: -11.6 ± 8.0%; ZOL+: -10.2 ± 8.2%). CONCLUSION: Two-year ADT in men with PCa led to a significant decrease of central and peripheral aBMD and of HR-pQCT derived bone microstructure and strength at the distal radius and tibia. Although ZOL prevented loss of aBMD in central and peripheral bone, bone area, volumetric BMD, microarchitecture, and strength significantly declined at the distal radius and tibia. These findings emphasize the importance of early risk assessment and guideline-based intervention and highlight the need for continued improvement of bone health strategies in men with prostate cancer undergoing ADT.