PIK3CA and head and neck squamous cell carcinoma: Among the HNSCC hallmark genes reported in COSMIC database, we observed recurrent mutations in TP53 (44%), NOTCH1 (20%), CDKN2A (12%), HRAS (12%), USP6 (8%); while, mutations in FANCA, HLA-A, PIK3CA, KMT2D and PDE4DIP were observed as non-recurrent (Fig. 1a).