PIK3CA and cancer: At the gene level, there are 18 genes showing more than five hotspots across all cancer types (in order, TP53, PIK3CA, PTEN, APC, KRAS, CTNNB1, FBXW7, CDKN2A, ARID1A, PIK3R1, NFE2L2, EGFR, NRAS, BRAF, HRAS, VHL, IDH1, ERBB2).