Effectivness of zoledronic acid in the treatment of osteoporosis in prostate cancer patients receiving GNRH agonist therapy

Introduction. It has been established that prolonged androgen-deprivation therapy (ADT) of prostate cancer leads to a decrease in bone mineral density (BMD) and increases the risk of fractures, which is an important medical and social problem. Zoledronic acid (ZA) is most often used for the prevention of osteoporosis against the background of ADT. The purpose of the study is to determine the efficacy and safety of ZA for the treatment and prevention of osteopo-rosis in non-metastatic prostate cancer against the background of ADT therapy with GnRH agonists. Materials and methods. The study included 45 men aged 54-81 years with morphologically verified prostate cancer (stages T2-4 N0-1 M0) who underwent surgical castration at least 6 months before inclusion or continuously received therapy with GnRH agonists. The blood level of CTX-1 was used as the main marker of bone resorption. To assess the BMD, the screening method of dual-band X-ray densitometry of the calcaneus with laser determination of the examination area - DXL using the CALSCAN apparatus and the DXL Calscan Workstation software was used. Patients were randomized into groups of 15 people each: Group 1 - received intravenous infusion of ZA at a dose of 4 mg at the beginning of the study and after 3 months of treatment; Group 2 received ZA at 2 mg in the same mode; Group 3 - control. For antire-sorptive therapy (ART), the drug Resorba (JSC «Pharm-Synthesis», Russia) was used. The duration of follow-up was 6 months. Results. In 13 out of 15 patients of Group 1, 3 months after the first administration of ZA, a decrease in the level of CTX-1 by 50% or more was observed, and after 6 months all 15 patients (100%) reached the age norm («complete answer»). Group 2 patients also responded to ART and by the 6th month 13 out of 15 (87%) had achieved a «complete response». In the control group by the 6th month the decrease in CTX-1 was not observed in any of the patients. Initially, the values of BMD in the studied groups did not differ. By the 3rd month of the study, the BMD index significantly increased only in Group 1. In Group 2 this indicator significantly increased by the 6th month of treatment. At the same time, in Group 1 after 6 months the BMD index reached higher values than in Group 2: an increase of 27% and 13%, respectively. In the control group, by the 6th month of observation, a significant decrease in BMD by 12% was noted. In Group 1, the number of patients with osteoporosis decreased to 6% and with a normal level of BMD - reached to 40%. Conclusion. High efficacy and sufficient safety of ZA in doses of 4 mg and 2 mg i/v one time in 3 months for anti-resorptive therapy in patients receiving long-term hormonal therapy with GnRH agonists has been demonstrated.