EGFR and adenocarcinoma: At present, it is believed that the EGFR mutation rate can reach up to 50% in nonsmokers, adenocarcinoma patients, Asian patients, and female patients.[3] The most common EGFR mutations were exon 19 deletions and L858r point mutations in exon 21.[4] Since the IPASS study in 2003.[5] EGFR-TKI monotherapy has become the first-line treatment option for EGFR-mutated non-small cell lung cancer, and multiple generation EGFR-TKIs have been developed (including erlotinib, gefitinib, icotinib (first generation),dacomitinib and afatinib (second generation), and osimertinib (third generation).