Erlotinib Versus Gemcitabine/Carboplatin in Chemo-naive Stage IIIB/IV Non-Small Cell Lung Cancer Patients With Epidermal Growth Factor Receptor (EGFR) Exon 19 or 21 Mutation

Inclusion Criteria: 1. Stage IIIB (cytological confirmed with malignant pleural effusion or pericardial effusion) or histopathological or cytological confirmed stage IV NSCLC or relapsed after complete resection . 2. EGFR exon19 deletions or exon 21 L858R mutation by the DNA direct PCR sequencing using fresh tumor sample or paraffin embed tumor sample. 3. Measurable lesions as defined by RECIST criteria . 4. Palliative radiotherapy allowed if it was finished 3 weeks after the first drug administration, but the target lesions should not be included in the radiotherapy field. 5. Patients with operation are allowed if the operation is 4 weeks before the first drug administration 6. Men or women of at least 18 years of age. 7. ECOG Performance status of 0 to 2. 8. Estimated life expectancy of at least 12 weeks. 9. Patient compliance and geographic proximity that allow adequate follow-up. 10. Adequate organ function tested 7 days before the first drug administration: hemoglobin ≥9 g/dL,absolute neutrophil count (ANC) ≥1.5\*109/L, platelets ≥100 \*109/L,bilirubin ≤1.5ULN, alkaline phosphatase (AP), aspartate transaminase (AST) and alanine transaminase (ALT) ≤2.5 upper limited number(ULN) (AP, AST, ALT ≤5ULN is acceptable if liver has tumor involvement).INR≤1.5, APTT in the normal range( 1.2DLN-1.2ULN),creatinine ≤1.5ULN. 11. Informed consent from the patient. Exclusion Criteria: 1. Have received systemic anti-cancer therapy, including Cytotoxic drugs, targeted therapy, experimental treatment, adjuvant or neo-adjuvant therapy(except the disease relapse 6 months after the final drug) 2. Wild type EGFR. 3. Uncontrolled pericardial or pleural effusions prior to study entry. 4. History of cardiovascular disease: Congestive Heart Failure \> grade II in NYHA. Unstable angina patients (have angina symptoms in rest) or a new occurrence of angina (began in the last 3 months) or myocardial infarction happens in the last 6 months 5. Brain metastasis (controlled brain metastasis and steroid free need is excluded). 6. HIV infection 7. Active infection, \>grade 2 in Common Terminology Criteria for Adverse Events(CTCAE) version 3. 8. A history of operation or serious traumatic 3 weeks before the first drug administration 9. Patient with other malignant tumor except NSCLC 5 years previous to study entry. Excluding cervical carcinoma in situ, cured basal cell carcinoma, bladder epithelial tumor \[including Ta and Tis\] 10. Mixed with small cell lung cancer 11. Unable to swallow drugs. 12. Malabsorption 13. Pregnant or child breast feeding women 14. Childbearing patients will not use a reliable method of contraception before the study entry, during process of the study and within 30 days after discontinuation of the study. Reliable contraceptive methods will be determined by principal investigator or a designated officer.