CXCR4 and neoplasm: Many retrospective studies have documented the expression of various chemokine receptors, particularly the C-X-C chemokine receptor 4 (CXCR4), and the association with higher recurrence incidences and cancer-related deaths, tumor size, advanced tumor-node-metastasis (TNM) stage, and shorter survival, predicting poor prognosis to cancer patients [3, 4].