Third-generation EGFR-TKI Treatment in Metastatic EGFR-mutant NSCLC

Inclusion Criteria:

* Pathologically confirmed non-small cell lung cancer;
* clinical stage IV (AJCC, 8th edition, 2017);
* EGFR sensitizing mutations (L858R or 19del);
* age≥18 years old;
* KPS score≥70;
* complete systemic imaging (including brain MRI) before third-generation EGFR-TKI treatment;
* received standard third-generation EGFR-TKI therapy (monotherapy or combined with brain radiotherapy);
* willing to cooperate with the follow-up after third-generation EGFR-TKI treatment;
* informed consent of the patient.

Exclusion Criteria:

* Multiple primary or metastatic tumors (except early skin cancer, cervical carcinoma in situ that has been treated radically, with no recurrence or progression for more than 5 years);
* Pregnant or lactating women who, as judged by the investigator, were not candidates for brain MRI;
* Uncontrolled epilepsy, central nervous system disease, or history of mental disorders, judged by the researcher to potentially interfere with the signing of the informed consent form or affect patient compliance.;
* patients without EGFR sensitive mutations or with unknown EGFR mutation status.

Withdrawal criteria

* The investigators considered that the patients had poor adherence to the study protocol.
* The patient withdrew informed consent and asked to withdraw.
* There was any safety reason (adverse event) considered by the investigator;
* Due to other underlying diseases, side effects, economic factors, and other reasons, patients did not receive regular doses of third-generation EGFR-TKI (continuous withdrawal time more than 1 week, cumulative withdrawal time more than 2 weeks, etc.).
* The patient was not followed up according to the protocol.
* Other circumstances in which withdrawal from the study was deemed necessary by the investigator.