It has been observed in these and other non-NGS studies that EGFR/ERBB2 or FGFR1/3 receptor tyrosine kinases, downstream PIK3CA and sometimes HRAS and PTEN, as well as tumor suppressors CDKN2A and TP53 are the most frequently altered genes in HNSCC. Here, PTEN is linked to head and neck squamous cell carcinoma.