Inclusion Criteria:

- Written informed consent provided.

- Males or females aged ≥18 years, < 75 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.