The accumulation of gene mutation damage is inevitably related to the occurrence of cancer, such as EGFR, K-RAS, ROS-1 and lung cancer; BRCA1/2, PIK3CA hotspot mutations (N345K, E542K, E545K, H1047L and H1047R), PIK3R1 gene mutations (E160D, Q329L, D560Y) and breast cancer; IDH1 R172 mutation and glioma; and somatic mutations of GUCY2F, EPHA3 and NTRK3 mutations and the occurrence of breast cancer, lung cancer and pancreatic cancer [115-117]. The gene discussed is PIK3CA; the disease is lung cancer.