Application of a fracture risk algorithm to men treated with androgen deprivation therapy for prostate cancer

Osteoporosis causes morbidity and mortality in men. The National Osteoporosis Foundation recommends fracture risk assessment with the online WHO/FRAX tool. Although androgen deprivation therapy for prostate cancer increases fracture risk, there is limited information about which men require preventative drug therapy. We applied the WHO/FRAX tool to men treated with androgen deprivation therapy for prostate cancer.

Information was collected from a practice cohort of men treated with gonadotropin-releasing hormone agonists, and included age, height, weight, history of gonadotropin-releasing hormone agonist treatment, dual energy x-ray absorptiometry results, prior bone targeted therapy and clinical risk factors for fracture. Subjects were evaluated with the WHO/FRAX algorithm (http://www.shef.ac.uk/FRAX/).

A total of 363 men treated with androgen deprivation therapy (median age 72 years) were evaluated. By the FRAX algorithm with clinical information (no dual energy x-ray absorptiometry data) the 3% hip fracture risk threshold for treatment was exceeded by 51.2% of the men (median risk 3.1%). When subjects were grouped by age the treatment threshold was reached by 3.3% of those younger than 70 years, 76.6% of those 70 to 79 years old and by 98.8% of those 80 years old or older. Using FRAX with bone mineral density data in the 93 patients who underwent bone mineral density testing the median 10-year hip fracture risk was 0.9% and the treatment threshold was exceeded by 15% of these subjects.

In this cohort of men receiving androgen deprivation therapy the prevalence of risk sufficient to necessitate drug therapy was high and was strongly influenced by age. The WHO/FRAX algorithm identifies a greater proportion of men for treatment than the traditional threshold of T score -2.5 or less.