The purpose of this study is to determine whether 100mg erlotinib had similar effect compared with 150mg erlotinib in NSCLC patients with EGFR mutation in China.

In China it was confirmed that 150mg Erlotinib was effective in NSCLC patients wtih EGFR mutation, but reducing dose occurring in some patients because of the drug related side-effects. Thus, we sought to investigate that in Chinese patients with EGFR mutation whether low dose (100mg) Erlotinib had similar efficacy but lower toxcities compared with standad dose (150mg) Erlotinib.

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.