Assessing fracture risk in men on ADT
Patients receiving ADT should be fully apprised of all the potential AEs. We suggest that clinicians should put together an educational handout distributed by the office staff that includes all the potential AEs and therapies to prevent and treat these AEs. We consider this extremely important, as ADT will significantly alter numerous aspects of the patient’s quality of life, some of which can be potentially obviated by changes in lifestyle and medical therapies.
Furthermore, the patient’s primary care physician should be alerted to the AEs of ADT—including an increase in serum lipids, insulin resistance, cardiovascular risks, and osteoporosis—so the primary care physician can participate in limiting these risks. We will focus our subsequent discussion on bone health in men on ADT.
When initiating ADT, a focused history and physical examination should evaluate the risk factors for osteoporosis and fracture, including prior fracture history, smoking, alcoholism, chronic glucocorticoid therapy, age, risk for falling, and BMI.18 A BMD study (dual-energy X-ray absorptiometry [DEXA] scan) should be obtained at baseline for men suspected of having osteopenia or osteoporosis, after one to two years of ADT, and then possibly every two to three years depending on risk factors and results of prior studies.
Likewise, a BMD study should be performed on men on long-term ADT who have never had one. As defined by the World Health Organization (WHO), osteoporosis exists when the BMD value is 2.5 or more standard deviations below normal values of a healethy young male (T-score <-2.5), and osteopenia is defined as a T score ranging between -1.0 and -2.5.19 In elderly men, spinal BMD, as measured by a DEXA scan, may be falsely elevated as a result of osteoarthritis; therefore, femoral neck bone density in elderly men is used routinely for the diagnosis of osteoporosis.20
Fracture risk can be assessed clinically by the practitioner based on the history, physical, and BMD results. Alternatively, the 10-year risk of a major osteoporotic fracture or a hip fracture can readily be obtained using the WHO Fracture Risk Assessment calculator found here. This tool takes into account multiple risk factors for fracture such as age, BMI, prior fracture, prior steroid use, and femoral neck BMD. The tool requires weight and height in kilograms and centimeters. There is a user friendly accompanying metric conversion calculator, which directly inputs the results into the FRAX calculator.
Recommended thresholds for treatment from the National Osteoporosis Foundation (NOF) are a >3% 10-year risk for hip fracture and a >20% 10-year risk for major osteoporotic fractures.21 When using the FRAX tool to assess fracture risk for men on ADT, for question 10 check “yes” for “secondary osteoporosis,” and we would suggest the easiest way to list the femoral neck BMD would be to use the “T-score” option.
An example of the FRAX score for a 71-year-old male with a height of 5 foot 8 inches weighing 155 pounds on ADT with a T-score of -2 at the femoral neck is shown in Figure 1 below.