NEW YORK (Reuters Health) - Beyond the well-known association of androgen deprivation therapy (ADT) with an accelerated decline in areal bone mineral density (aBMD), the treatment also affects bone in other ways, according to a cross-sectional study. "The current study is one of few to date that has also measured additional properties of bone, such as the structure of different types of bone, which contributes to overall bone strength and the risk of fracture," Jack Dalla Via of Deakin University in Geelong, Australia told Reuters Health by email. "This is important as changes or differences in bone structural properties can markedly alter whole bone strength and fracture risk, independent of any change or difference in bone density." "Our study showed that in addition to lower DXA-assessed bone density of the lumbar spine, men treated with ADT had lower bone density and reduced bone strength at bone sites of the forearm and lower leg, with the honeycomb-like trabecular bone, rather than the dense cortical bone, mostly affected by this treatment," he said. "Clinically, this is important because trabecular bone loss starts earlier in life and deteriorates at a greater rate than cortical bone throughout life, with some evidence that it is also more strongly associated with fracture risk than cortical bone." Dalla Via and colleagues studied 192 mostly white men with a mean age of about 70: 70 with prostate cancer treated with ADT; 52 with prostate cancer but no ADT, and 70 healthy controls. On average, ADT-treated men had 7.9% higher body mass index than prostate cancer controls but not healthy controls. They were also more likely to have advanced disease and to have been previously treated with radiotherapy or chemotherapy compared to prostate cancer controls, who were more likely to have had a prostatectomy. There were no other relevant differences between groups. Assessments included lumbar spine DXA, proximal femur aBMD, pQCT distal (4%) and proximal (66%) tibia radius, cortical and trabecular volumetric BMD (vBMD), bone structure, strength and cortical bone distribution. As reported online June 9 in Bone, ADT-treated men had 7.2%-7.8% lower lumbar spine aBMD than either prostate cancer controls or healthy controls, and they trended toward lower total hip aBMD. At the distal tibia, total bone area was 6.2%-7.3% greater in ADT-treated men than in both controls but total vBMD was 8.4%-8.7% lower. Further, the bone strength index (BSI) was 10.8% lower in ADT-treated men relative to healthy controls only. 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%) compared to both controls. No other differences in bone outcomes at the proximal tibia or radius were identified. Summing up, the authors state, "ADT treatment for prostate cancer 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." "This study reinforces that it is important to monitor bone density in men treated with ADT for prostate cancer," Dalla Via said. "If a patient is identified as having low bone density or osteoporosis, then a treatment plan is needed that may include lifestyle approaches, such as exercise and dietary intervention, and/or pharmacological treatment." "An important area for future research," he added, "is to investigate whether interventions such as exercise training or nutritional supplementation can influence these properties, particularly in men treated with ADT for prostate cancer." Source
