PIK3CA and breast cancer: The top 10 mutated genes in breast cancer samples were TP53 (34%), PIK3CA (33%), TTN (16%), CDH1 (13%), GATA3 (12%), MUC16 (9%), MAP3K1 (8%), KMT2C (8%), MUC4 (8%) and PTEN (6%) (Fig. 1A).