A Retrospective Study About Treatment Strategy After First/Second Line EGFR-TKI Failure

This is a multi-center retrospective study, designing to access the best treatment strategy in non-small cell lung cancer (NSCLC) patients harboring EGFR mutant type after first/second line EGFR-TKI failure. The study end point is Progression Free Survival 2 (PFS2), which is defined as the time period from Progression Disease 1(PD1) to Progression Disease 2(PD2). PD1 is defined as the first tumor progression time from taking EGFR-TKI evaluated by Recist 1.1 criterion, and PD2 as the second tumor progression time after EGFR-TKI failure no matter what second/third line treatment was, PD2 is also evaluated by Recist 1.1 criterion.