Titration of dosage for the protective effect of zoledronic acid on bone loss in patients submitted to androgen deprivation therapy due to prostate cancer: a prospective open-label study.

BACKGROUND: Bisphosphonates were incorporated as agents for the long-term effect of androgen deprivation therapy (ADT) but no comparative study was established for the optimal schedule for bone preservation.

METHODS: Ninety-five consecutive prostate cancer patients submitted to radical retropubic prostatectomy were recruited. At rising PSA they were prospectively enrolled in nonrandomized fashion and grouped to receive no treatment (21 - control group), and monthly (17), bi-monthly (15), tri-monthly (19) or semestral (15) 4 mg zoledronic acid infusions. The patients were followed to a minimum of 30 months after receiving ADT by LHRH agonists. Bone mineral density (BMD) was measured every 6 months in all 5 studied groups in order to compare the effect of each regimen to nontreatment. Tukey-Kramer and Scheffe's tests were used.

RESULTS: The control group showed an impressive BMD loss throughout the study period. The 4 groups treated with zoledronic acid infusions showed increased BMD in the lumbar area on periodical densitometry and no statistical differences could be established among the 4 studied schedules. Different individual patterns of decreasing (control) or increasing (treated) BMD could be seen along the study as measured by bone densitometry.

CONCLUSIONS: Zoledronic acid treatment promoted effective osseous protection against the natural demineralization process in patients with prostate cancer recurrence submitted to ADT.