A clinicopathological study of mediastinal lymph node metastasis of lung cancer

BACKGROUND: To investigate the characteristics of mediastinal lymph node metastasis of lung cancer from a view of pathology. METHODS: Radical pulmonectomy or lobectomy combined with extensive dissection of mediastinal lymph node was carrived out in 398 patients with lung cancr. N2 disease was diagnozed in 160 cases, and total 352 groups of mediastinal lymph node invaded were analyzed. RESULTS: N2 disease appeared as single group, multi-groups and jumping-form groups, comprising 41.2%,58.8% and 29.3% respectively. The highest metastatic site of lymph node was group 7 mediastinal lymph node, the followings were group 4, 3 and 5 lymph nodes, comprising 45.6%, 31.3% and 25.6% respectively. The N2 metastasis was highly correlated with the site, size, histological classification and cell differentiation of the cancer. An another characteristic of N2 metastasis was that the metastatic lymph node could invaded into the bronchial wall, especially in adenocarcinoma. CONCLUSIONS: It is necessary to dissect the lymph nodes of the hilar and upper and lower mediastinum at the homolateral thoracic cavity extensively and completely. Attention should be paid to the bronchial wall invasion by the metastatic lymph nodes, too.