PIK3CA and head and neck squamous cell carcinoma: However, 14 events were found at higher prevalence in HPV+ than in HPV– HNSCC (SNVs in PIK3CA, ZNF750, EP300, CYLD, TRAF3, FGFR3, PTEN, B2M and RB1 and arm-level events +3q, −11q, −16q, −18q and +19q).