INTRODUCTION
The distant metastasis of cancer cells has long been known to have characteristic preferences.1–2 Bone is one of the most common metastatic sites for malignancies, such as breast, prostate, and lung cancer.3 Bone metastases can be categorized into osteolytic metastases with bone resorption, osteoblastic metastases with excessive bone formation, and a mixed pheno-type of both.4–5 According to the"seed and soil"hypothesis, bone metastasis is dependent on the interactions between tumor cells and the bone microenvironment.