Metabolic bone disease induced by prostate cancer: Rationale for the use of bisphosphonates

Purpose: Increasing evidences indicate that despite the osteoblastic nature of metastatic bone lesions due to prostate cancer osteolysis is a regular feature and may cause skeletal morbidity. This observation provides the rationale for the use of bisphosphonates for managing bone metastatic prostate cancer. Materials and Methods: We reviewed the literature on the mechanisms by which prostate cancer affects bone cell function and disrupts physiological bone turnover. We also summarized the clinical results of bisphosphonate fbr treating bone pain in patients with prostate cancer. Results: Metastatic prostate cancer in bone interferes with physiological bone remodeling by abnormal release of the hormones and paracrine factors physiologically involved in the modulation of osteoblastic and osteoclastic activity. Tumor induced bone formation and resorption develop within the same metastasis but excessive new bone is deposited away from bone resorption sites and does not contribute to bone strength. The increase in bone resorption may also be a generalized phenomenon that is most likely due to iatrogenic osteoporosis or related to hyperparathyroidism in response to the increased calcium demand. The bone resorption index in patients with bone metastatic prostate cancer correlates with bone pain and is an independent predictor of adverse skeletal events. However, small clinical studies of the efficacy of bisphosphonates for controlling bone pain in patients with prostate cancer show contradictory results. Conclusions: Improved understanding of the pathophysiology of prostate cancer induced metabolic bone disease implies that bisphosphonates may have a role in the treatment of this disorder. This issue is being addressed by large-scale ongoing randomized studies.