CCR7 and head and neck squamous cell carcinoma: Multiple studies have demonstrated that the incidence and progression of HNSCC are closely associated with mutations and gene expression variations, including variation in CTTN, D2HGDH, NLRP2, PEX11A, UPK and SERPINE1 and mutations in CCR7, KL, LGR5 and RORB, which are associated with HNSCC prognosis (13, 14, 15).