EGFR-TKI Concurrent With/Without WBRT in Brain Metastasis From NSCLC

Inclusion Criteria: * Patients who was confirmed non-small cell lung cancer (NSCLC) by histology or cytology, harboring EGFR mutant type (19 and/or 21 exon mutation). * Patients who was confirmed with asymptomatic, treatment naive brain metastasis (didn't receive any treatment after diagnosed with brain metastasis) by MRI, couldn't receive operation or stereotactic radiosurgery（SRS）. * Appraisable disease, that is there must be at least one lesion with the longest diameter\>10mm in brain (by brain MRI). * Adult patients (18 to 75 years old). Eastern Cooperative Oncology Group（ECOG） performance status 0 to 2. Life expectancy of at least 12 weeks. Haemoglobin \> 10g/dl, absolute neutrophil count (ANC) \> 1.5 x 10\^9/L, platelets \> 100 x 10\^9/L; total bilirubin \< 1.5x upper limit of normal (ULN). Alanine aminotransferase（ALT） and aspartate aminotransferase（AST）\< 1.5x ULN in the absence of liver metastases, or \< 5x ULN in case of liver metastases. Creatinine clearance \> 60ml/min (calculated according to Cockcroft-gault formula). * Patients should be contraceptive during the period of the trial. Exclusion Criteria: * Patients who had received brain radiotherapy or EGFR-TKI before. * Patients who can't receive WBRT. * Uncontrolled intracranial hypertension after steroid or dehydration therapy. * Patients who take phenytoin, Carbamazepine, Rifampicin, Barbital, or St John's Wort which will interfere with the metabolism of TKI. * Patients with interstitial lung disease, significant ocular disease, or serious uncontrolled systematic disease. * Patients who can't take oral tablets, with active peptic ulcer diseases. * Pregnancy or breast-feeding women.