14643 Background: Androgen deprivation therapy (ADT) is a widely administered treatment for prostate cancer. However, ADT is associated with accelerated bone loss, osteoporosis, and fractures (Shahinian, NEJM 2005; 352:154). According to Smith et al, annual bone loss on ADT approaches 9% (Smith, NEJM 2001;345:948), using QCT densitometry, a highly sensitive test for the detection of osteoporosis in men. Intravenous bisphosphonates (pamidronate, zolendronate) have been shown to prevent ADT-related bone loss in randomized phase III trials. We performed a retrospective analysis to determine if oral bisphosphonates effectively prevent bone loss in men receiving ADT. Methods: Twenty two men, ages 60–80, were placed on alendronate or risendronate at the initiation of ADT. Baseline and follow-up bone mineral densitometry (BMD) studies were performed with QCT densitometry. Repeat BMD was performed 12- 27 months (mean = 17mo) after the baseline BMD. Percentage change in bone density was annualized. Within each treatment group, the hypothesis of no mean change from baseline was analyzed using a paired t test. Results: Mean baseline bone density was 122.6mg/cc. Mean follow-up bone density was 112.7mg/cc. For the whole group, the annualized mean change in BMD was negative 7.77%/yr (p = 0.0003). Of note, 9/22 men maintained or gained bone density (-1.26% to +5.95%). 13/22 men lost at least 6.03% (-6.03% to -23.2%). There was no unexpected toxicity or fractures. Conclusions: In this retrospective study, prophylactic oral bisphosphonates do not protect against accelerated ADT-induced bone loss in men with prostate cancer. No significant financial relationships to disclose.
