TKI Followed by Thoracic Radiotherapy for Stage IV EGFR Mutant NSCLC

Inclusion Criteria: * Age ≥18 and ≤75; * ECOG performance status 0-1; * Patients must provide study specific informed consent prior to study entry; * Pathologically or cytologically diagnosed as NSCLC; * EGFR activating mutation to TKI approved by histology, cytology or circulation tumor DNA; * Stage IV NSCLC with ≤ 3 metastatic lesions (AJCC, 8th ed.) confirmed by meticulous radiographic examination. Brain MRI and 18F PET/CT is strongly recommended unless there is a contraindication; * Patients have received≥3 months of TKI therapy and do not received disease progression; * HB ≥ 10.0 g/dL; * Absolute number of neutrophil granulocyte ≥ 1.5 × 109/L; * Absolute number of PLT ≥ 100 × 109/L; * Total bilirubin ≤ 1.5 folds of the maximum extent; * ALT and AST ≤ 2.0 folds of the maximum extent; * Cr ≤ 1.25 folds of the maximum extent and Ccr ≥ 60mLl/min. Exclusion Criteria: * Patients have received thoracic radiotherapy before; * Malignant pleural effusion, pericardial effusion or peritoneal effusion; * Patients have severe pulmonary comorbidity, such as ILD, COPD or other active pulmonary disease; * Any unstable systemic disease including active infection, uncontrolled hypertension, unstable angina, CHF (NYHA ≥ II), MI within 6 months of enrollment, severe arrhythmia requiring medication，hepatic, nephric or metabolic disease; * HIV infection； * Pregnancy or lactation women; * ECOG status ≥2； * Mixed SCLC component; * Other factors that is considered ineligible.