Impact of androgen deprivation therapy (ADT) on bone mineral density (BMD) over 3 years in men with nonmetastatic prostate cancer.

Abstract

193 Background: Decreased BMD is a common side effect of ADT, leading to increased fracture risk. Although loss of BMD appears to be greatest within the first 12 months of starting ADT, few data on BMD changes exist beyond 12 months, and other risk factors for bone loss in men on ADT are not well-characterized. Methods: Men age 50+ with non-metastatic prostate cancer and starting continuous ADT were enrolled in a prospective longitudinal study. BMD was determined by dual-energy x-ray absorptiometry at baseline and yearly for 3 years. A matched control group of men with prostate cancer but not on ADT was also enrolled. Medication use was recorded at each visit. Multivariable regression analyses were done to examine predictors of BMD loss. Results: 80 ADT users and 80 controls were enrolled (mean age 69.4 y); 49.7% had osteopenia and 4.6% had osteoporosis at baseline. ADT was associated with significant losses in lumbar spine BMD in year 1 compared to controls (p=0.004) and trends towards greater declines at femoral neck and total hip sites. Changes in year 2 and 3 were much smaller and not statistically different from controls (Table). Vitamin D use but not calcium use was associated with improved BMD at the lumbar spine in year 1 (+5.77%, p=0.006) with positive trends at other sites (+2.19% femoral neck, +1.76% total hip) primarily in year 1. Age was not associated with changes in BMD. Conclusions: Losses in BMD with ADT use are greatest at the lumbar spine and in the first year compared to years 2 and 3 and are independent of age. Vitamin D appears to be protective particularly in the first year of ADT use. [Table: see text]