FGFR4 and head and neck squamous cell carcinoma: Several studies inspected the relationship between FGFR4 gene rs351855 G>A polymorphism and numerous types of cancer including breast cancer [13–18], cervical cancer [19–21], colon cancer [13,18,22], gastric cancer [23], prostate cancer [24–27], head and neck squamous cell carcinoma (HNSCC) [28,29], oral squamous cell carcinoma (OSCC) [30,31], lung cancer [32–34], hepatocellular carcinoma [35–37], sarcoma [38], skin cancer [39], neuroblastoma [40], non-Hodgkin’s lymphoma [41], and glioma [42].