Alendronate Curbs Androgen Deprivation Bone Loss

By David Douglas

NEW YORK (Reuters Health) Oct 11 - Oral alendronate had beneficial effects on bone in men starting androgen deprivation therapy (ADT) for non metastatic prostate cancer in a phase III trial reported by Canadian researchers.

This study, Dr. Laurence H. Klotz told Reuters Health by email, "confirms that alendronate, an inexpensive oral pill taken once per week, with few side effects, completely reverses the loss of bone mineral density associated with androgen deprivation therapy, and indeed results in an increase in average bone mineral density (BMD) in these men."

In a September 11th online paper in European Urology, Dr. Klotz and colleagues at Sunnybrook Health Sciences Center, Toronto note that bone loss is greatest during the first year of ADT -- which suggests that preventive therapy should be started early.

To investigate further, the team studied 186 men who were starting ADT with leuprolide acetate 30 mg IM every four months. They randomly assigned them to also receive alendronate 70 mg or placebo once weekly. Both groups also took calcium 1 g and vitamin D 400 IU daily.

At one year, the alendronate group showed a mean spine BMD gain of 1.7% whereas the placebo patients had a 1.9% loss. Corresponding values at the total hip were a gain of 0.7% compared to a drop of 1.6%.

The researchers say that because loss of BMD has been clearly established as correlating with fracture risk, they chose it as a surrogate end point rather than fracture reduction in order to achieve a manageable cohort size and follow-up length. And in fact, the study was closed early because of slow accrual.

Bone markers also revealed benefit, with median urinary N-terminal crosslinking telopeptide of type I collagen values decreasing by 3.5% in the alendronate group and increasing by 16.5% in the placebo group.

Corresponding changes in median bone-specific alkaline phosphatase were a decrease of 2.25% in the active treatment group and an increase of 3.12% in placebo patients. Overall, safety and tolerability were similar in both groups.

The results with alendronate, concluded Dr. Klotz, suggest "that it should be more widely utilized for men initiating androgen deprivation therapy for the management of prostate cancer."