SRT for Residual Oligometastases of NSCLC After 3rd Generation EGFR-TKIs

Inclusion Criteria:

* The patient has a diagnosis of pathologically confirmed NSCLC by tumor biopsy and/or fine-needle aspiration.
* The patient has a diagnosis of American Joint Committee on Cancer (AJCC) 8th Edition stage IV NSCLC.
* The patient receives 3rd generation EGFR-TKI in the first line setting.
* The patient is ≥18 years of age and ≤75 years of age at the time of screening.
* The patient's Karnofsky performance score (KPS) is ≥70 at study entry.
* The patient has adequate baseline tumor assessment before initiation of 3rd generation EGFR-TKI.
* The patient has at least one measurable lesion according to Response Evaluation Criteria in Solid Tumors (RECIST), version 1.1.
* The patient presents with a residual "oligometastatic" state after 3rd generation EGFR-TKI therapy that would be amenable to consolidative SRT in the opinion of the investigator.
* The patient has signed informed consent.
* EGFR Exon19 deletion or Exon21 L858R mutation

Exclusion Criteria:

* History of another malignancy or concurrent malignancy. Patients with cervical carcinoma in situ or adequately treated basal cell carcinoma who have been disease free for \> 5 years are eligible.
* The patient is pregnant (confirmed by serum b-HCG if applicable) or is breastfeeding.
* Patients with uncontrolled epilepsy, mental disorders, drug abuse, or social condition that may affect compliance or ability to sign a written informed consent in the opinion of the investigator.
* Patients with residual metastatic disease after 3rd generation EGFR-TKI therapy that is deemed not amenable to consolidative SRT.