Abstract

Thorax computed tomography (CT) and mediastinoscopy have important roles on clinical staging of lung cancer. In this study, to determine the N component of the TNM staging system, CT findings and the results of mediastinoscopy were compared with the pathologic examination of surgical specimens after thoracotomy. We defined 10 mm as the upper limit of normal for the short axis of the nodes in thoracic CT. Thoracotomy was performed in 21 cases whose mediastinal lymph nodes were normal by CT findings. Three patients (14%) who had been judged to have no metastasis by CT were found to have N2 disease after examination of the surgical specimens. Mediastinoscopy was performed in 21 cases who had mediastinal lymph nodes larger than 10 mm in short axis. Thirteen cases among 21 patients (62%) were determined as inoperable by mediastinoscopy because of mediastinal lymph node metastasis. Amoung eight patients (38%) who had been judged to have no metastasis by mediastinoscopy, only one had N2 disease after examination of the surgical specimens. In the identification of mediastinal lymph node metastases, thorax CT was 82% sensitive, 72% specific, and 76% accurate. CT scan is one of the best screening procedures for selecting patients with a high probability of mediastinal involvement. In patients with positive findings, the diagnosis should be confirmed by mediastinoscopy.