Factors involved in lymph node metastasis in clinical stage I non-small cell lung cancer—From studies of 604 surgical cases

SummaryPurposeTo identify the factors involved in lymph node metastasis, 604 clinical stage I non-small cell lung cancer cases were studied.Materials and methodsAge, sex, Brinkmann Index (BI), histopathological type, histopathological differentiation degree, tumor size and CEA value were studied as factors involved in lymph node metastasis for 604 cases that were diagnosed to be clinical stage I (T1-T2N0M0; 1997 TNM categorization) non-small cell lung cancer.ResultsLymph node metastasis was observed in 161 cases (27%). The factors involved in lymph node metastasis included the degree of histopathological differentiation and the tumor size. While the metastasis rate was less than 10% in well-differentiated cancers (even when the tumor size exceeded 4 cm), in moderately differentiated and poorly differentiated cancers, the lymph node metastasis rate increased in proportion to tumor size.ConclusionIn stage I non-small cell lung cancer cases, cases with a low probability of lymph node metastasis are well-differentiated cancers. In these cases, lymph node dissection may be omitted in surgery (reduction surgery), and such cases may thus be good subjects for undergoing either stereotactic body radiotherapy (SBRT) or particle therapy.