Bone mineral density, structure, distribution and strength in men with prostate cancer treated with androgen deprivation therapy

Androgen deprivation therapy (ADT) improves survival in men with advanced prostate cancer (PCa), but has been associated with compromised skeletal health and increased fracture risk. However, limited previous research has investigated determinants of bone strength beyond DXA-derived areal bone mineral density (aBMD) in this population group. The aim of this cross-sectional study was to investigate the effects of ADT in men with PCa on BMD, bone structure, estimates of whole bone strength and cortical bone distribution. A total of 70 ADT-treated men, 52 PCa controls and 70 healthy controls had DXA lumbar spine and proximal femur aBMD and pQCT distal (4%) and proximal (66%) tibia and radius cortical and trabecular volumetric BMD (vBMD), bone structure, strength and cortical bone distribution assessed. Analyses included BMI and/or tibia/radius length as covariates. On average, ADT-treated men had a higher BMI than PCa (P < 0.05) but not healthy controls. ADT-treated men had 7.2–7.8% lower lumbar spine aBMD than PCa (P = 0.037) and healthy controls (P = 0.010), with a trend for a lower total hip aBMD in the ADT-treated men (P = 0.07). At the distal tibia, total bone area was 6.2–7.3% greater in ADT-treated men than both controls (P < 0.01), but total vBMD was 8.4–8.7% lower in ADT-treated men than both controls (P < 0.01). Moreover, bone strength index (BSI) was 10.8% lower relative to healthy controls only (P < 0.05). At the distal radius, ADT-treated men had lower total and trabecular vBMD (10.7–14.8%, P < 0.05) and BSI (23.6–27.5%, P < 0.001) compared to both controls. There were no other differences in bone outcomes at the proximal tibia or radius. In conclusion, ADT treatment for PCa was associated with lower BMD and estimated compressive bone strength, particularly at trabecular skeletal sites (lumbar spine, and distal tibia and radius), compared to controls, but there were no consistent differences in cortical bone structure, distribution or bending strength.