Recently, through sequencing analysis of cancer genomes, considerable advancements have been made in identifying cancer genes with “driver” mutation, such as TP53 (Moon et al., 2019), KRAS (Polom et al., 2019), BRAF (Yang et al., 2018a), EGFR (Paez et al., 2004), and PIK3CA (Harada et al., 2016). The gene discussed is PIK3CA; the disease is cancer.