CXCR4 and head and neck squamous cell carcinoma: Although previous study has demonstrated that SDF-1/CXCR4 axis may be a potentially therapeutic target for HNSCC (De-Colle et al., 2017), other studies shown that high CXCR4 is related to poor overall survival in the univariate but not in multivariate analysis (Albert et al., 2012) and SDF-1 expression is not statistically significantly associated with overall survival in multivariated analysis (Rave-Fränk et al., 2016).