Active Surveillance for Limited GGNs

Patients eligible for enrollment in the study are required to meet all the following criteria. 1. Demonstrates the following on thin-section computed tomography (TSCT) scan: 1. Presence of one or two GGNs (bilateral lesions are permitted). 2. All lesions have remained stable without regression or enlargement for at least 3 months. 3. The dominant lesion (the lesion with the largest maximum tumor diameter) has a maximum tumor diameter ≥0.6cm and ≤2cm. 4. CTR ≤0.25 in lesions. 5. No lymph node with a diameter \>1cm in the mediastinal view. 6. Not adjacent to the pleura in dominant lesion and no sign of pleural retraction in any lesions. 2. Has not previously undergo any anti-tumor drug or radiation therapy for the lung lesions. 3. Aged 18-75 years. 4. Eastern Cooperative Oncology Group (ECOG) performance status of 0 or 1. 5. Written informed consent. Patients will be excluded if they meet any of the following criteria. 1. History of any prior malignancies within the past 5 years. 2. History of lung surgery. 3. History of interstitial pneumonia, pulmonary fibrosis or other severe pulmonary diseases. 4. Presence of severe or uncontrolled diseases that may possibly reduce the 10-year life expectancy.