[Rational lymph node dissection for lung cancer according to the occurrence lobe and histological type]

Between January 1989 and December 1998, 134 cases of squamous cell carcinoma and 244 cases of adenocarcinoma underwent surgical resection of the lung with systematic lymph node dissection in our hospital. The cN diagnosis by CT scan and pN diagnosis were compared. In squamous cell carcinoma pN 2-3 cases were only one patient (2%) out of 60 patients with cN 0, 5 patients (18%) out of 28 patients with cN 1, and 21 patients (46%) out of 46 patients with cN 2-3. On the other hand in adenocarcinoma pN 2-3 cases were 27 patients (14%) out of 193 patients with cN 0, 3 patients (25%) out of 12 patients with cN 1, and 24 patients (62%) out of 39 patients with cN 2-3. The pathways of the lymphatic metastases to the mediastinal nodes were analized in 27 patients with squamous cell carcinoma and 54 patients with adenocarcinoma undergoing systematic lymph node dissection. All patients had histologically proven mediastinal metastasis. Histologically there was no difference in pathways of the lymphatic metastases to the mediastinal nodes. 1. The dominant lymphatic drainage from the right upper lobe flowed into the superior mediastinal nodes. The direct metastatic passages to the superior mediastinal nodes were observed (47%). Subcarinal and inferior mediastinal node involvement was rare (3%). 2. The dominant lymphatic drainage from the middle and the lower lobe flowed into the subcarinal nodes (85%). The involvement of the superior mediastinal nodes occurred in 53% of subcarinal node positive patients on the right side. 3. The dominant lymphatic drainage from the left upper lobe flowed into the subaortic or paraaortic nodes (69%). Subcarinal and inferior mediastinal node involvement was rare (6%). We conclude that subcarinal and inferior mediastinal lymph node dissection is not necessary for upper lobe lung cancers, and that superior mediastinal lymph node dissection can be omitted in middle and lower lobe lung cancers without hilar and subcarinal lymph node involvement, especially in the cases of cN 0.