PIK3CA and head and neck squamous cell carcinoma: We observed significant co-amplification of CCND1, FGF19, ORAOV1, FADD (P-value < 0.01, Co-occurrence); PIK3CA and SOX2 (P-value < 0.001) in this study and TCGA-tongue tumors, which contains genes implicated in cell cycle, cell death/NF-kB pathway and, consistent with previously described in HPV-negative HNSCC tumors [6], [7] (Supplementary Fig. 4a).