Bone loss in men with prostate cancer: Risk factors, detection, and prevention

Prostate cancer is one of the most common cancer types in men in Western countries. In 2008 it was estimated that nearly 900,000 men were diagnosed with prostate cancer worldwide. Prostate cancer typically starts as a localized disease, progressing to nearby tissues (eg, seminal vesicles), before metastasizing to distant sites such as the skeleton. Growth of prostate cancer is fueled by testosterone. Androgen-deprivation therapy (ADT) is used to treat men with both locally advanced disease as well as men with metastatic disease. ADT is effective for slowing the growth of prostate cancer, but it can also lead to substantial bone loss with a resulting increase in fracture risk. There are a number of additional risk factors in this patient population that may further contribute to bone loss and fracture risk. These include low weight, smoking, alcohol consumption, and other co-morbid conditions and medications. In general, bone loss and osteoporosis in older men, even those treated with ADT, is underdiagnosed and, thus, undertreated. Several tools are available for detection of bone loss or assessment of fracture risk. These include dual-energy X-ray absorptiometry (DXA), FRAX®, an online fracture risk assessment tool incorporating clinically determined risk factors that can be used in combination with DXA results, and measurement of biochemical markers of bone turnover. While multiple options are available for treating bone loss, only denosumab (Prolia®; 60 mg every 6 months SC) is approved to increase bone mass and reduce the risk of fracture in that population. In this review we will discuss (i) the prostate cancer disease course, (ii) ADT and other risk factors for bone loss in this patient population, (iii) tools available to the clinician for detection of bone loss; and (iv) treatment options for bone loss.