Lymph node metastasis of T1, T2 squamous carcinoma and adenocarcinoma of lung: characteristics and clinical significance.

OBJECTIVES: To investigate the frequency, distribution and features of lymph nodes metastasis in T(1)/T(2) squamous carcinoma and adenocarcinoma of lung, and to provide evidence for extensive dissection of lymph nodes. METHODS: 254 patients with T(1)/T(2) squamous carcinoma and adenocarcinoma of lung underwent R2 surgery plus extensive dissection of hilar, interlobular and mediastinal lymph nodes according to the grouping system proposed by Naruke. RESULTS: A total of 1 685 groups of lymph nodes were dissected. The metastatic rates of N(1) and N(2) were 20.0% and 10.2%. The difference was very significant between T(1) and T(2) (P < 0.01). No, N(2) metastasis was found in T(1) squamous carcinoma. N(2) metastatic rates were 22.0% in squamous carcinoma and 40.9% in adenocarcinoma (P < 0.01). 64.3% of squamous carcinomas spread to only one group of N(2) nodes, and over 3 groups of lymph nodes were positive in 46.2% of adenocarcinomas. Saltatory metastasis accounted for 57.5% of N(2) metastasis. 13.6% of N(2)-positive tumors in the upper lobes metastasized to the lower mediastinum, whereas 51.6% of N(2)-positive tumors in the lower lobes spread to the upper mediastinum. CONCLUSIONS: The frequency of lymph node metastasis increases with the growth of tumors. Metastasis occurs more frequently in adenocarcinoma than in squamous carcinoma. Tumor at any site can metastasize to the distant mediastinum. Except for T(1) squamous carcinoma, radical surgery can be achieved only by extensive dissection of ipsilateral intrapulmonary and mediastinal lymph nodes.