Efficacy of zoledronic acid in older prostate cancer patients undergoing androgen deprivation therapy

Abstract Objectives The purpose of this study is to evaluate the efficacy of annual zoledronic acid treatment in Japanese patients with nonmetastatic prostate cancer during androgen deprivation therapy (ADT). Methods This is a single institution 12-month study. Between 2016 and 2019, patients aged 70 years or older on ADT for nonmetastatic prostate cancer had bone mineral density (BMD) measured and 10-year probability of fracture calculated using fracture risk assessment tool (FRAX). Patients who showed osteopenia or had a 10-year hip fracture risk ≥ 3% or a 10-year probability of major osteoporotic fracture ≥ 20% were offered treatment with zoledronic acid 5 mg intravenously (ZA group). The patients who did not receive treatment were set as the control group. Lumbar and hip BMD were measured 6 and 12 months after treatment in the ZA group and 12 months after baseline in the control group. The yearly BMD change of both groups was compared. Results The mean ages of the ZA group (n = 26) and control group (n = 12) were 80.5 ± 9.1 and 76.1 ± 6.7 years, respectively. In the ZA group, lumbar and hip BMD changes at 12 months were +2.1% and +0.8%, respectively. In the control group, lumbar and hip BMD changes were −0.9% and −4.9%, respectively. There were statistically significant differences between the 2 groups in BMD percent changes (P  Conclusions Without intervention, BMD tends to continue to decrease during ADT. Our findings suggest that administration of zoledronic acid enables maintenance of BMD in the older adults.