Progressive decrease in bone density over 10 years of androgen deprivation therapy in patients with prostate cancer.

OBJECTIVES: Several reports suggest an increased incidence of osteoporosis and concomitant fractures in men receiving androgen deprivation therapy (ADT) for prostate cancer. We sought to estimate the longitudinal effects of ADT on loss of bone density in this cross-sectional study.
METHODS: Hip and spine bone mineral density (BMD) studies were performed by dual-energy x-ray absorptiometry on 36 patients with prostate cancer. The year 0 cohort (n = 8) consisted of patients who had not yet begun planned ADT. These men were compared to patients receiving ADT who underwent BMD evaluation at year 2 (n = 6), year 4 (n = 7), year 6 (n = 5), year 8 (n = 5), and year 10 (n = 5) of therapy. All BMD values for the patients with prostate cancer were compared to age-matched control subjects.
RESULTS: Hip BMD was significantly lower in patients on ADT (mean BMD 0.802 g/cm(2)) compared with those not on ADT (mean BMD 0.935 g/cm(2)). Patients at year 0 had hip and spine BMD similar to age-matched control subjects. There was a significant trend for decreased hip BMD with increasing years of ADT (r = 0.46, P = 0.00008). This relationship was more dramatic when hip BMD at each time point was compared to age-matched control subjects (r = 0.55, P = 0.5 x 10(-16)). This bone loss was evident even up to year 10. BMD loss was more dramatic in patients who had undergone surgical castration than those receiving medical ADT (P = 0.08). Patients on intermittent ADT had similar BMD loss as patients on continuous ADT at year 2 and year 4 but demonstrated less bone loss at year 6 (P = 0.07) despite equivalently low testosterone levels.
CONCLUSIONS: There is diminished BMD with increasing duration of ADT. Continuous ADT and surgical castration may be more deleterious than medical therapy, particularly when the medical therapy is given in an intermittent fashion.