Inclusion Criteria:

1. Histological or cytological documented stage IIIB (not amenable for radical /loco-regional therapy) or stage IV (metastatic) adenocarcinoma of lung. Sputum cytology alone is excluded.
2. Measurable disease, according to the Response Evaluation Criteria in Solid Tumours (RECIST), the presence of at least one unidimensionally measurable lesion with longest diameter ≥ 20 mm by conventional techniques OR 10 mm by spiral CT scan.
3. Age ≥ 65.
4. Life expectancy of at least 3 months.
5. Never previously treated with radiotherapy, chemotherapy or surgery for malignant disease.
6. Neutrophil count ≥ 1.5 × 109/L or platelets ≥ 75× 109/L or hemoglobin ≥ 10g/dL
7. Adequate hepatic function including prothrombin time ≥70%of the reference, AST/ALT ≤2.5×institutional upper limit of normal (ULN) or ≤5×ULN if liver metastases, alkaline phosphatase ≤5×ULN (or ≤20×ULN if liver metastases),total bilirubin ≤1.5×ULN
8. Male or female. Age ≥ 18 years.
9. Written (signed) informed consent.
10. Able to comply with study and follow-up procedures.

Exclusion Criteria:

1. Patients with prior surgery or thoracic radiotherapy.
2. Patients with prior chemotherapy or othersystemic anti-tumour therapy (e.g. monoclonal antibody therapy or EGFR-TKI) .
3. Lack of physical integrity of the upper gastrointestinal tract, or malabsorption syndrome, or inability to take oral medication, or active peptic ulcer disease.
4. Any inflammatory changes of the surface of the eye.
5. Any diseases, metabolic dysfunction, physical examination finding, or clinical laboratory finding giving reasonable suspicion of a disease or condition that contraindicates the use of any study medication (Erlotinib,Capecitabine) or that might affect the interpretation of the results or render the subject at high risk from treatment complications.
6. Pregnant or lactating women.
7. Woman of childbearing potential with either a positive or no pregnancy test at baseline. Postmenopausal women must have been amenorrhoeic for at least 12 months to be considered of non-childbearing potential.
8. Sexually active males and females (of childbearing potential) unwilling to practice contraception during the study.
9. 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).
10. History of another malignancy within the last 5 years except cured basal cell carcinoma of skin and cured carcinoma in-situ of uterine cervix.
11. Patient who are at risk (in the investigator's opinion) of transmitting human immunodeficiency virus (HIV) through blood or other body fluids are excluded.
12. Patients who have brain metastasis or spinal cord compression that has not yet been definitively treated with surgery and/or radiation will be excluded; previously diagnosed and treated CNS metastases or spinal cord compression without evidence of stable disease (clinically stable imaging) for at least 2 months will also be excluded.
13. Hypersensitivity to Erlotinib or Capecitabine