PIK3CA and head and neck squamous cell carcinoma: Tumor 1 showed a characteristic HNSCC mutation profile including the amplification of 3q26/28 (TP63, SOX2, PIK3CA), FGFR1, 11q13 (CCND1, FADD, CTTN), E2F1, PTK2, loss of NSD1 and LOH in CDKN2A and TP53 (20).