PIK3CA and neoplasm: The 5 most frequently altered pathways were the PI3K/AKT/mTOR pathway with 12 of 20 tumours (60%) harbouring focal amplifications and/or homozygous deletions and/or mutations, followed by the chromatin remodelling (45%) and ubiquitin mediated proteolysis (UBP) (35%) pathways and those involved in cell cycle regulation (35%) and squamous cell differentiation (30%) (Figure 3).