Erlotinib 100mg or 150mg in Treating EGFR Mutated NSCLC

Inclusion Criteria: 1. Histological diagnosis of NSCLC with phase IIIB or IV disease; 2. Sensitive mutation EGFR gene (18, 19 del, 21 L858R gene mutation) (mutation detection methods:ARMS-PCR, sequence method) 3. Never received anti-tumor therapies for the advanced stage; 4. Never used EGFR inhibitors; 5. Measurable disease by RECIST criteria; 6. Male or female patients \>=18 years of age; 7. ECOG karnofsky performance 0\~3, life expectancy is greater than 12 weeks; 8. Patients must be accessible for treatment and follow-up; Exclusion Criteria: 1. Previously used EGFR inhibitors 2. Mix ingredients in patients with squamous cell carcinoma, small cell lung cancer; 3. Allergic to erlotinib; 4. Non-measurable lesions 5. Pregnant or lactating women; 6. Patients having other factors that preventing researchers from enrollment them.