METABOLIC BONE DISEASE INDUCED BY PROSTATE CANCER:: RATIONALE FOR THE USE OF BISPHOSPHONATES

Formation of pre-metastatic bone niche in prostate cancer and regulation of traditional chinese medicine

Prostate cancer with bone metastasis has a high cancer-specific mortality. Thus, it is essential to delineate the mechanism of bone metastasis. Pre-metastatic niche (PMN) is a concept in tumor metastasis, which is characterized by tumor-secreted factors, reprogramming of stromal cells, and immunosuppression by myeloid-derived suppressor cells (MDSC), which is induced by bone marrow-derived cells (BMDC) in the target organ. However, PMN does not explain the predilection of prostate cancer towards bone metastasis. In this review, we discuss the initiation of bone metastasis of prostate cancer from the perspective of PMN and tumor microenvironment in a step-wise manner. Furthermore, we present a new concept called pre-metastatic bone niche, featuring inherent BMDC, to interpret bone metastasis. Moreover, we illustrate the regulation of traditional Chinese medicine on PMN.

Bisphosphonates in the management of metastatic prostate cancer

Prostate cancer (PCA) frequently metastasizes to the bones, and skeletal metastases represent the most common cause of morbidity in advanced PCA. Besides the development of skeletal events due to metastases, patients with PCA are at higher risk for benign osseous complications, such as osteoporosis and fractures. Bisphosphonates (BPs) have emerged as an integral part of the management of skeletal disease related to PCA. Currently available data support their routine use to prevent androgen-deprivation-induced osteoporosis and its secondary complications. Dosing at 3-month intervals is appropriate; further studies will have to demonstrate the efficacy of annual dosing. In men with already established bone metastases, BPs might be helpful in preventing skeletal-related events in patients who do not respond to alternative therapies and are at high risk for bone fractures or spinal cord compression. In patients with hormone-refractory prostate cancer, BPs might be administered for analgesic purposes. Prospective randomized trials will have to explore the clinical role of BPs in the prevention of bone metastases following local therapy with curative intent in men at high risk for PCA recurrences.