[Clinical significance of extended mediastinal lymph node dissection on the basis of clinicopathological analysis of nodal involvement in bronchogenic carcinoma].

During the past 20 years, 1,064 cases of non-small cell lung cancer underwent resectional surgery in which all accessible mediastinal lymph nodes were dissected. Among 288 patients with histologically proven N2 disease, 182 underwent complete dissection of the mediastinal lymph nodes; 77 had one-level and 105 had multi-level metastases. Fifteen percent of the patients having primary lesions with a maximal diameter between 21 and 30 mm had N2 disease. Nodal metastases to the lower mediastinum from upper lobe cancer (nonregional metastasis) were frequently observed as were metastases of lower lobe cancer to the upper mediastinum. In addition, there were often skip metastases to the nonregional parts of the mediastinum without regional nodal involvement in the mediastinum. Among left-lung cancer patients, the group that underwent nodal dissection after mobilization of the aorta by dividing the Botallo's ligament frequently had a verified metastatic node at the tracheo-bronchial angle (#4) which might not have been detected without that procedure. In addition, many N2 and N3 diseases were detected by additional dissection through a median sternotomy. From the results of the present study, it appears that extensive mediastinal dissection should be recommended in surgery for lung cancer irrespective of the location and the size of the primary tumor.