Progressive osteoporosis during androgen deprivation therapy for prostate cancer

Hypogonadism is a prominent risk factor for osteoporosis in older men. However, bone loss during androgen ablation therapy for prostate cancer has rarely been quantitated.

Femoral neck bone mineral density was determined in 26 men before orchiectomy or chemical castration as initial hormone therapy for prostate cancer and at 6-month intervals thereafter for 6 to 42 months. Measurements were made in 16 other men at 12 to 24 months beginning 3 to 8 years after the onset of castration. Baseline and post-castration bone loss was related to several host and tumor characteristics, and compared to similar measurements in 12 control subjects.

Average age corrected baseline femoral neck bone mineral density was higher in controls than in treated men and remained essentially unchanged for 2 years. Following orchiectomy average bone mineral density decreased 2.4% and 7.6%, respectively, during years 1 and 2 (2-year loss 2.5% to 17.0%), with similar losses documented in men undergoing chemical castration. Average bone mineral density decreased 1.4% to 2.6% per year 3 to 8 years after uninterrupted androgen deprivation. Age corrected baseline bone mineral density was greater in men who were obese, younger than 75 years or participated in regular exercise but the influence of each characteristic could not be isolated. Post-castration bone loss was greater in men who were obese, younger than 75 years without regular exercise.

Chemical or surgical castration in men with prostate cancer is usually followed by greatly accelerated bone loss which may be superimposed on a bone mass already depleted before hormonal therapy. Baseline bone mass and subsequent bone loss may be influenced by host obesity, age and exercise habits.