To evaluate the efficacy and safety of SBRT for T1N0M0 non-small cell lung cancer

To evaluate the efficacy and safety of SBRT for T1N0M0 non-small cell lung cancer，the following questions should be answered. Can SRT be an alternative standard treatment modality for inoperable patients? Can SRT can be a comparable standard treatment modality with lobectomy for operable patients? 12 Gy is the daily dose at the isocenter，and 48 Gy in total by 4 fractions will be irradiated by stereotactic irradiation over 4 to 8 days.

Inclusion Criteria:

1. Histologically or transbronchoscopic cytologically confirmed non-small cell lung cancer
2. Stage IA with images within 28 days
3. No other intrathoracic lesions
4. Dose constraints of the organs at risk seem to be limited within range
5. Operable (Standard or Limited surgery) or Inoperable
6. Age>=20
7. No previous thoracic radiation
8. No previous chemotherapy
9. ECOG PS=0-2
10. Respiratory function (<=14 days) PaO2>=60 torr FEV1.0>=700 ml
11. Written informed consent

Exclusion Criteria:

1. No apparent radiation pneumonitis and fibrosis
2. No active tuberculosis without oral drugs
3. No double cancer
4. No pregnancy
5. No psychiatric disorder
6. No steroid administration