Careful evaluation about mediastinal involvement is important in the management of patients with non-small cell lung cancer. Invasive staging procedure such as mediastinoscopy is advocated because of the unreliability of noninvasive staging methods such as CT, MRI. We compared differences between pre- and postoperative staging in non-small cell lung cancer without lymphadenopathy on CT scan and investigated the methods for more accurate preoperative staging.

1) Records of a total of 41 patients with preoperative T1-3N0M0 non-small cell lung cancer were reviewed and the histologic types of tumors were squamous cell carcinoma in 32 cases, adenocarcinoma in 6 cases and large cell carcinoma in 3 cases. Twenty-four cases were central lesions and seventeen cases were peripheral lesions.

2) Among the 32 cases with preoperative T2, 2 cases were identified postoperatively as T3 with invasion of chest wall and among 6 cases with preoperative T1-3, 1 case was identified postoperatively as T4 with invasion of aorta and pulmonary arteries.

3) After the operation of 35 cases with T1-2, 5 cases wore N1 and 3 cases were N2 postoperatively. After the operation of 6 cases with T3, 2 cases were N1 and 3 cases were N2 postoperatively Preoperative T3 showed more intrathoracic lymph node metastases and higher N2/N1 involvement ratio than preoperative T1-2.

4) Complete surgical resections were done in 34 out of 41 cases. Incomplete resection were done in all postoperative N2 tumors.

Invasive staging procedures such as mediastinoscopy should be considered in the case of preoperative T3 non-small cell lung cancer even though mediastinal lymphadenopathy is not recognized on the CT scan of the chest.