Pemetrexed Combined With Synchronous Gefitinib as Adjuvent Therapy in Patient With EGFR Mutant Lung Adenocarcinoma

Inclusion Criteria: * Written informed consent provided. * Males or females aged ≥18 years, \< 70 years. * Able to comply with the required protocol and follow-up procedures, and able to receive oral medications. * Target population is completely resected pathological stage II-IIIA(N1-N2) NSCLC with EGFR exon 19 deletions and exon 21 L858R activating mutation. * Patient who can start the investigational therapy within 3-6 weeks after the complete resection * ECOG performance status 0-1. * Life expectancy ≥12 weeks. * Adequate hematological function: Absolute neutrophil count (ANC) ≥2.0 x 109/L, and Platelet count ≥100 x 109/L, and Hemoglobin ≥9 g/dL (may be transfused to maintain or exceed this level). * Adequate liver function: Total bilirubin ≤ 1.5 x upper limit of normal (ULN), Aspartate aminotransferase (AST), alanine aminotransferase (ALT) ≤ 2.5 x ULN in subjects without liver metastases; ≤ 5 x ULN in subjects with liver metastases. * Adequate renal function: Serum creatinine ≤ 1.25 x ULN, or ≥ 60 ml/min. * Female subjects should not be pregnant or breast-feeding. Exclusion Criteria: * Known severe hypersensitivity to gefitinib or any of the excipients of this product. * Known severe hypersensitivity to pre-medications required for treatment with cisplatin / vinorelbine doublet chemotherapy. * Inability to comply with protocol or study procedures. * A serious concomitant systemic disorder that, in the opinion of the investigator, would compromise the patient's ability to complete the study. * A serious cardiac condition, such as myocardial infarction within 6 months, angina, or heart disease. * Interstitial pneumonia. * Patients with prior exposure to agents directed at the HER axis (e.g. erlotinib, gefitinib, cetuximab, trastuzumab). * Patients with prior chemotherapy or therapy with systemic anti-tumour therapy (e.g. monoclonal antibody therapy). * Patients with prior radiotherapy * History of another malignancy in the last 5 years with the exception of the following:Other malignancies cured by surgery alone and having a continuous disease-free interval of 5 years are permitted. Cured basal cell carcinoma of the skin and cured in situ carcinoma of the uterine cervix are permitted. * Any unstable systemic disease (including active infection, uncontrolled hypertension, unstable angina, congestive heart failure, myocardial infarction within the previous year, serious cardiac arrhythmia requiring medication, hepatic, renal, or metabolic disease). * Eye inflammation or eye infection not fully treated or conditions predisposing the subject to this. * Evidence of any other disease, neurological or metabolic dysfunction, physical examination or laboratory finding giving reasonable suspicion of a disease or condition that contraindicated the use of an investigational drug or puts the subject at high risk for treatment-related complications. * Patient who has active serious infection (e.g. pyrexia of or 38.0℃ over) * Patients who harbouring exon 20 T790M mutation.