Assess the Efficacy of Whole Brain Radiation Therapy in Lung Cancer Patients With Brain Metastasis

Inclusion Criteria: * Patients must have signed a written informed consent form prior to any study specific screening procedures * 18 years or older * KPS ≥ 50% * Histologically confirmed adenocarcinoma of the lung * Activating mutation of EGFR * Newly diagnosed CNS metastasis or in progression with at least one measurable lesion in the brain (defined as any lesion \> 1 cm on T1-weighted contrast enhanced MRI) * Patients could enter the study regardless of previous treatment (included chemotherapy) for metastatic extracranial disease, except TKI. * No steroids or stable or decreasing dose of steroids for at least 5 days before the MRI evaluation. * Adequate hematologic, liver and renal functions: neutrophil count ≥ 1.5 x 109/L; platelets ≥ 100 x 109/L; Hb ≥ 9 g/Dl; Total bilirubin \< 1.5 x ULN; AST or ALT \< 2.5 x ULN (\< 5 x ULN in patients with liver metastases); Serum creatinine ≤ 1.5 x ULN or Creatinine clearance ≥ 50 mL/min Exclusion Criteria: * Prior treatment of brain metastases with WBRT or TKI * Patient eligible for radiosurgery or surgical resection * Contre indication at the radiotherapy * Leptomeningeal disease * Previous history of cancer (other than curatively treated basal and squamous cell carcinoma of the skin and/or in-situ carcinoma of the cervix) within the the 5 years before study entry * Prior treatment with Gefitinib or other TKI * Pregnant or breast feeding women * Women with an intact uterus (unless amenorrhoeic for the last 24 months) not using effective means of contraception