Tumour DNA, as determined by the presence of somatic mutations (TP53: 72%, p16 (CDKN2A): 22%, p110a (PIK3CA): 21%, and Notch Receptor 1 (NOTCH1): 19%) is highly specific for HNSCC in The Cancer Genome Atlas (TCGA) data [19]. Here, PIK3CA is linked to head and neck squamous cell carcinoma.