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