Sun C, et al. - This study was designed to test a presumption that pathological biomarkers including CD34 positive endothelial cell and microvessel density (MVD) of the primary breast tumor can serve as predictors of the probability of occurrence of bone metastases and offer information for appropriate therapeutic strategies at an early stage. Findings demonstrated a strong correlation of quantitative CD34 positive endothelial cell and MVD measurements of the primary breast tumor with the occurrence rate of bone metastases, which predicted the probability of occurrence for bone metastases at an early stage.