Osteoporosis and fractures after androgen deprivation initiation for prostate cancer.

INTRODUCTION: Androgen deprivation therapy (ADT) is widely utilized for treatment of localized and advanced prostate cancer (CaP). ADT is associated with increased rates of osteoporosis; however, its impact on fracture risk is not completely understood. We investigated incidence and predisposing factors for osteoporosis and fractures in a large, contemporary, single institution series of patients treated with ADT for CaP.
METHODS: We retrospectively reviewed medical records of all patients who received ADT for CaP between 1/1989 and 7/2005. Primary endpoints of investigation were osteoporosis and non-pathologic fractures. Independent variables included age, race, body mass index (BMI), pretreatment serum PSA, Gleason sum, clinical stage, ADT type (medical versus surgical) and schedule (continuous versus intermittent), and receipt of calcium, vitamin D or bisphosphonate supplementation. Data were analyzed by Chi-square test, Student's t-test, Linear Regression, and Logistic Regression (p < 0.05 significant).
RESULTS: A total of 395 patients were analyzed (mean age 71.7 years, 59% African American, 41% Caucasian/other). At mean follow-up of 66.1 months, 92 (23%) patients developed osteoporosis and 27 (7%) patients developed non-pathologic fractures. On univariate analysis, age, race, BMI, and ADT duration were significantly associated with osteoporosis development, while BMI, ADT duration, and presence of osteoporosis were significantly associated with fracture incidence. Regression analysis revealed that age > 70 at ADT initiation, continuous ADT, and increased treatment duration predicted osteoporosis development, while only osteoporosis was independently predictive of fracture development.
CONCLUSIONS: Patients receiving continuous ADT for CaP are at increased risk for developing osteoporosis which may lead to fractures, with an incidence of 7% in our study population.