[T1, T2 squamous or adenocarcinoma of the lung:characteristics of lymph node metastasis and its clinical significance].

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