CSF1 and neoplasm: Throughout the life span of PECC within MS, from early-stage tumor micro-metastatic foci that are beginning to vascularize to late-stage tumors that PC occurs, monocytes migrate through blood vessels into MS region under the influence of tumor-derived chemoattractants, including colony-stimulating factor-1 (CSF-1/M-CSF), the CC chemokines, and VEGF [64].