The purpose of this study is:

1. To establish a set of diagnostic criteria of intraoperative frozen section of early stage lung adenocarcinoma, including clinicopathologic and molecular characteristics.
2. To assess its clinical usefulness in guiding surgical procedure for early stage lung adenocarcinoma.

The detection rate of small pulmonary nodules is increasing due to the widespread use of high-resolution computed tomography (CT) screening in clinical practice. These minute pulmonary nodules are suggestive of atypical adenomatous hyperplasia (AHH), adenocarcinoma in situ (AIS), minimally invasive adenocarcinoma (MIA), and invasive adenocarcinoma. Hence, the precision diagnosis of intraoperative frozen section is particularly imperative for its fundamental role in assess indeterminate lung lesions and guide the extent of subsequent surgical procedure.

However, it is still difficult for the surgical pathologist to apply the various features according to the newly revised WHO classification of lung adenocarcinoma (2015) to guide surgical management due to their unascertained accuracy or heterogeneity of lung cancer or technique problem. Therefore, the establishment and assessment for a set of diagnostic criteria of intraoperative frozen section of early stage lung adenocarcinoma are our primary aim in this study.

Inclusion Criteria:

1. Patients with suspected pulmonary nodules (5~20 mm) by chest CT scan;
2. Patients received surgical operation.

Exclusion Criteria:

1. Patients compliance is poor and cannot accept follow-up;
2. Patients nursing or pregnant;
3. Patients with a history of any cancer;
4. Patients with confirmed pathological diagnosis or received radiotherapy or chemotherapy or target therapy preoperatively.