Moreover, the recent study reported that the somatic mutation of CASP8, a gene regulating apoptosis, only took place in oral squamous cell carcinoma, but almost not in pharyngeal squamous cell carcinoma [34], which was confirmed by the higher IWHMB of APOPTOSIS in oral squamous cell carcinoma than that in pharyngeal squamous cell carcinoma. This evidence concerns the gene CASP8 and oral cavity squamous cell carcinoma.