Radical mediastinal nodal removal improves disease-free survival for pulmonary low-grade malignant tumors.

To investigate the prognostic role of radical lymph node dissection in treatment for pulmonary Low Grade Malignant Tumors (LGMTs); specifically, on the extent of nodal removal and its impact on long-term survival.A total of 93 LGMTs cases underwent surgical resection and were histopathologically confirmed. Overall survival rates and disease-free survival were respectively calculated according to the extent of lymph node resection and histopathological grades of tumors. Risk factors of nodal involvement and survival predictors were calculated via multivariate analysis. Life table, Kaplan-Meier, and Cox regression models were used for the statistical analysis.Thirty-eight cases of carcinoid, 17 adenoid cystic carcinomas, and 38 mucoepidermoid carcinomas were included in the current study. Twenty-one cases were high-grade and 72 were low-grade. A total of 813 lymph nodes were removed, at an average of 8.7±5.4 nodes per patient. The numbers of harvested nodes were 11.8±4.5, in the study group via radical nodal removal and 4.0±2.4 nodes per patient in the nodal sampling group. Eleven cases showed lymph nodal involvement (5 mediastinal and 6 hilar lymph node metastasis). No significant differences of overall survival was found among the different histological types (p=0.939), or the extent of nodal removal (p=0.971). Meanwhile, there was a significant difference of disease-free survival (DFS) rates according to the extent of nodal removal (5-YS: 97% of radical nodal dissection vs. 78% of nodal sampling, p=0.038). Overall survival and disease-free survival were closely associated with histological grading (OS: 78% of high grade vs. 97% of low grade, p=0.001; DFS: 57% of high grade vs. 97% of low grade, p<0.0001).Radical lymph node dissection improved disease-free survival for pulmonary low-grade malignant tumors, although no obvious improvement on overall survival was noticed. Histological grade was the most important prognostic factor in LGMTs.