The antiosteoporotic efficacy of intravenous pamidronate in men with prostate carcinoma receiving combined androgen blockade: a double blind, randomized, placebo-controlled crossover study.

Background: Prostate carcinoma therapy with combined androgen blockade may result in high bone-turnover with significant bone loss. This study was undertaken to evaluate the antiosteoporotic efficacy of intravenous pamidronate in a double blind, randomized, placebo-controlled, crossover study.

Methods: Twenty-one consecutive men with metastatic prostate carcinoma who were receiving combined androgen blockade with a long-acting gonadotropin-releasing hormone agonist (gosarelin acetate) and an androgen antagonist (flutamide or bicalutamide) were evaluated at baseline and at 6 and 12 months after therapy. They were randomly assigned to receive a single intravenous infusion of 500 mL of normal saline solution diluted with either pamidronate (90 mg) or placebo at baseline and with a crossover at 6 months. Lumbar-spine bone-mineral densities (BMDs) were measured by spinal quantitative computed tomography (QCT), femoral neck BMDs were measured by dual-energy X-ray absorptiometry (DXA), and markers of bone turnover were measured by noninvasive methods. Data on 10 men with localized prostate carcinoma who were treated with radiotherapy alone, over the same period, was collected for comparison studies.

Results: The mean age of the men was 75.1 years +/- 1.6 years. One man withdrew from the study because of deteriorating health, and two died from metastatic disease within the first 6 months. Combined androgen blockade normalized serum prostate-specific antigen activities (from an initial mean value of 86.2 ng/mL +/- 10.1 ng/mL) and maintained serum free testosterone concentrations in the hypogonadal range (< 2.2 pmol/L) in all men throughout the study. Treatment with pamidronate resulted in a 7.8% +/- 1.5% increase in mean lumbar spine QCT from 79.4 mg/cm(3) (95% confidence interval [CI], 64-94 mg/cm(3)) to 85.6 mg/cm(3) (95% CI, 70-101 mg/cm(3)) (P = 0.0005) and a 2% +/- 0.9% increase in mean total femoral neck DXA from 0.98 g/cm(2) (95% CI, 0.90 -1.05 g/cm(2)) to 1.0 mg/cm(2) (95% CI, 0.91-1.08 g/cm(2)) (P = 0.02). Conversely, treatment with placebo, resulted in a 5.7% +/- 1.6% decrease in mean lumbar spine QCT and a 2.3% +/- 0.7% decrease in mean total femoral neck DXA (P = 0.0001 and P = 0.0007 for the comparison of percentage change between the pamidronate and placebo treatments). After pamidronate therapy, serum bone Gla-protein concentrations decreased by 16.8% +/- 5.9%, and urinary deoxypyridinoline excretion rates decreased by 18.5% +/- 12.8% (P < 0.01 respectively for the comparison between pamidronate and placebo treatment).

Conclusions: This study demonstrated that a single intravenous infusion of pamidronate (90 mg) significantly reduced the high bone turnover and bone loss (for at least 6 mos) in men with prostate carcinoma who had been rendered hypogonadal with combined androgen blockade therapy.