PIK3CA and neoplasm: With the exception of tumor 2, all tumor samples showed characteristic mutations of HNSCC including amplification of 3q26.2 (TP63, SOX2, PIK3CA) (1), 5q14.3 (APC) (13, 29, 30), 8q24.3 (PTK2) (25), 8q22.3 (LRP12) (27) as well as loss and/or LOH of 9p21.3 (CDKN2A) (1, 31).