Approximately half of these men will receive Androgen Deprivation Therapy (ADT) at some point after their diagnosis. While ADT helps to treat prostate cancer and prolong survival for older men, it can lead to bone loss and increased risk of fracture. Hormones such as testosterone and estrogen are known to protect against bone loss. Therefore when these hormones are blocked, bones become less dense and can break more easily. This can cause osteoporotic or low trauma/fragility fractures, bone pain, and decline in mobility. In men with prostate cancer, fractures are also associated with increased mortality. For such patients, effective screening and timely interventions are essential for reducing bone-related morbidity.
“The use of androgen deprivation therapy for prostate cancer in men is likely to result in accelerated bone loss; however there is still hope for an improved quality of life while minimizing negative bone effects, if timely managed bone health care services are provided for patients on ADT.”
Due to the age range in which prostate cancer develops, a significant proportion of men already have an important degree of bone loss before even starting treatment for prostate cancer. Up to 1 in 8 men age 65 or older have osteoporosis independent of prostate cancer . Therefore Osteoporosis Canada recommends screening for osteoporosis with Bone Mineral Density (BMD) testing for all men older than 65 and for younger men with clinical risk factors for fracture.
However, BMD alone is only moderately predictive of fracture risk. Validated tools such as the FRAX, a Fracture Risk Assessment System from the World Health Organization (WHO) released in 2008, along with Canadian Association of Radiologists and Osteoporosis Canada (CAROC) tools incorporate additional risk factors such as age and prior fragility fracture to improve fracture predictions. In the United States, the National Osteoporosis Foundation (NOF) recommends a dual-energy x-ray absorptiometry (DXA) scan (to measure BMD) for men diagnosed with prostate cancer before initiation of ADT. The results of this baseline (pre-ADT) test can help guide subsequent bone health care. However, it was discovered that when the more detailed FRAX tool is employed, a significant number of men are found to be at elevated risk for fracture, despite DXA T-scores that are within normal limits.
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Our study looked to identify the specific tests ordered, and the quality of services provided by a specialized osteoporosis clinic at the initial clinic visit, and whether the results of commonly ordered tests such as BMD, baseline blood counts with vitamin D levels, bone turnover markers, and Serum Protein Electrophoresis (SPEP), affected subsequent management for the patients on ADT. The goal was also to understand whether or not men on ADT had their fracture risk systematically assessed with any tool such as the CAROC/FRAX tool at baseline. Even though such tools are not specifically validated in men on ADT, they are widely recommended by experts in the field as the most appropriate option at the present time. We also continued to monitor if the recommended tests by the physicians for 100 study patients (median age 73) were implemented within the first 6 months of the initial clinic visit.
Prescribed pharmacological interventions were documented for all patients seen in the clinic, taking vitamin D, calcium (from all sources) and bone targeted medication for the patients who were diagnosed with osteopenia or osteoporosis before visiting the specialized clinic.
Some important findings were that 29% of the study population were taking more than 1200 mg daily calcium and 23% were taking <500 mg of calcium daily from all sources, while 30% of the patients were not taking the appropriate amount of vitamin D.
The main findings were that patients seen in the clinic had very high rates of adherence to published guidelines around lifestyle modification, appropriate doses of calcium and vitamin D being prescribed, and almost 100% use of systematic fracture risk assessment with the CAROC tool by the clinic. No patients were inappropriately prescribed antiresorptive therapy (e.g. those at low fracture risk).
In summary, the single osteoporosis clinic we studied in Toronto performed a comprehensive assessment and recommended guideline-based bone health care for the vast majority of the men on ADT, suggesting a systemic approach to assessing bone health is associated with high rates of guideline-adherent care. We also noticed a few interesting trends. First, radiation oncologists were more inclined to refer a patient to the osteoporosis clinic compared to urologists. Second, a significant proportion of men were taking excessive amounts of calcium, which is associated with gastrointestinal upset, kidney stones, and possibly an increased risk of cardiovascular disease. Third, a number of men starting ADT did not undergo BMD testing until at least 6 months after starting ADT (in contrast to guideline-recommendations). An important limitation is that our study involved a single physician in a single specialized osteoporosis clinic. Little is known about the quality of care provided to men on ADT in other such clinics. Despite high knowledge about appropriate bone health care among prostate cancer specialists, there remain significant gaps in screening and monitoring of bone health, suggesting the need to develop innovative strategies to overcome barriers to implementation and prevent gaps in guidelines for those who can benefit. Since many urologists and radiation oncologists report feeling ill-equipped to manage bone health issues in the men they are initiating on ADT, one collaborative approach could involve referring these men to an osteoporosis clinic.
Written by: Baig S, Chahin R, Breunis H, Alibhai SMH, University Health Network, Toronto, ON, Canada
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