Bone mineral density screening in patients with prostate cancer on androgen-deprivation therapy: Data from a single center

ADT is considered an effective first-line treatment for men with both advanced and non-metastatic prostate cancer. Despite the importance of ADT in prostate cancer treatment, ADT is associated with potential side effects, including BMD reduction, resulting in increased risk of osteoporosis and fractures.^1,2 The pathophysiologic reason is that when testosterone is reduced the usual balance between osteoblast-mediated bone formation and osteoclast-mediated bone resorption is disrupted, with bone resorption outstripping formation. Osteoclast activity is at least in part mediated by parathyroid hormone (PTH). Studies have shown that testosterone increases bone density by inhibiting PTH-mediated osteoclast activity.^3–5 Testosterone also exerts a bone-protective effect via conversion to estrogen. In men who have low testosterone concentration due to ADT (or any cause), osteoclast activity is not appropriately inhibited, leading to increased bone resorption and therefore bone loss or osteoporosis. ⁶ It has been shown that during the first year of exposure to ADT, there is a five- to 10-fold increase in the rate of bone loss as well as fracture risk. This risk increases as the duration of ADT therapy increases.^7,8

In men with non-metastatic prostate cancer receiving ADT, BMD can be maintained or increased significantly by treatment with bisphosphonates, zoledronic acid, alendronate, or pamidronate.^9–13

At Loyola University Medical Center, 5222 men were diagnosed with prostate cancer between January 2006 and January 2014. Of 513 men who were treated with a gonadotropin-releasing-hormone (GnRH) agonist, 105 (20%) had a DXA scan. Of 487 men who were treated with anti-androgen therapy, 103 (21%) had a DXA. Out of 278 men who received both GnRH agonist and anti-androgen therapy, 64 (23%) received a DXA.

These findings suggest that the deleterious effects of ADT on bone are not well recognized and that efforts should be made to raise the level of awareness of this important risk factor.