Osimertinib Combined With Intracranial SRT for EGFR-Mutant NSCLC With Symptomatic Brain Metastases

Inclusion Criteria:

* Age ≥18 years, Male or female
* Pathologically confirmed Stage IV metastatic non-squamous non-small cell lung cancer (NSCLC) with documented positive EGFR sensitive mutation (EGFR 19del and L858R) and MRI confirmed brain metastases, diagnosed within 6 weeks prior to treatment initiation within baseline period
* Received first-line osimertinib monotherapy during observation period
* Upfront brain SRT during observation period
* Baseline ECOG scored 0-2
* Symptomatic brain metastases during baseline period\*
* Complete imaging evaluation of systemic lesions (including brain MRI) during baseline period and before osimertinib treatment
* At least 1 follow-up brain MRI during observation period
* Baseline BM: ≤10 Brain metastases, largest tumor \<10 mL in volume and \<3 cm in longest diameter; total cumulative volume ≤15 ml \*Symptomatic brain metastases are defined as any neurological symptom in relation to the diagnosed BM, occurred within 30 days after brain metastases diagnosis.

Exclusion Criteria:

* Leptomeningeal metastases at stage IV NSCLC diagnosis
* Whole brain radiotherapy treated BM during observation period
* Patients received other systemic anti-tumor therapy in addition to osimertinib as 1L treatment during observation period
* Secondary or multiple primary tumors at stage IV NSCLC diagnosis
* Patients received any adjuvant targeted therapy after previous surgery