BACKGROUNDTo investigate the relationship between the size of primary tumor, pathologic classification, cell differentiation or location of tumor and lymph node metastasis in lung cancer.

METHODSThree hundred and thirty-two patients with lung cancer underwent pulmonectomy plus extensive dissection of hilar and mediastinal nodes. The law of lymph node metastasis was analyzed.

RESULTSA total of 3 280 lymph nodes were removed. Metastatic rates of N1 and N2 were 29.9% and 22.4% respectively. The total lymph node metastatic rates of T1, T2, and T3 diseases were 8.5%, 27.4% and 61.2% respectively ( P < 0.005). No lymphatic metastasis was observed in well-differentiated squamous cell carcinoma, however, the lymph node metastatic rates in moderate- and poor-differentiated squamous cell carcinoma were 16.8% and 19.6% respectively. The lymph node metastatic rates were 27.5% and 71.6% in moderate- and poor-differentiated adenocarcinoma respectively ( P < 0.005). The total lymph node metastatic rates in central and peripheral squamous cell carcinoma were 19.6% and 11.7% respectively ( P < 0.005), while in adenocarcinoma, the rates were 57.9% and 24.0% respectively ( P < 0.005). The N2 metastatic rates in central and peripheral squamous cell carcinoma were 10.9% and 2.9% respectively ( P < 0.005), while in adenocarcinoma, the rates were 47.5% and 17.8% respectively ( P < 0.005 ). Under the same T status, cell differentiation or location of tumor, the metastatic rate of adenocarcinoma was much higher than that of squamous cell carcinoma ( P < 0.005 ).

CONCLUSIONSThe frequency of lymph node metastasis significantly correlate with size of primary tumor, pathological classification, cell differentiation and location of tumor.