PIK3CA and lung carcinoma: D Ross et al. reviewed the acquired resistance to EGFR TKI in lung cancer and found that the second EGFR mutation comprised approximately 60% (the T790 M mutation was approximately 40–55%), the bypass activation mutation was approximately 20% (Met amplification 5%, HER2 amplification 8–13%, Sclc 10%, BRAF 1%, PIk3CA 1–2% and EMT 1–2%), and other unknown mechanisms accounted for 15–20% [21].