PIK3CA and non-small cell lung carcinoma: While TP53 and KRAS are among the most frequently altered genes across cancer types, distinct hotspot variants are specific to distinct cancer types, such as activating EGFR variants in exons 18 to 21 in non-small cell lung cancer (NSCLC)[64] or PIK3CA variants in codons 542, 545 and 1047 in breast cancer [18].