Positivity rates for CXCL12 and CXCR4 at the primary cancer site reach 42.2–90.0% and 32.3–80.0% by immunohistochemistry (IHC) detection, respectively, which are significantly higher than those in the adjacent normal mucosa tissues 17, 18, 19, 20, 21, 22, 23, 24. This evidence concerns the gene CXCR4 and cancer.