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

Abstract

Purpose: 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.

Materials and methods: 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/).

Results: 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.

Conclusions: 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.