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. Here, CXCL12 is linked to cancer.