Predictors of nodal metastasis and prognostic significance of lymph node ratio and total lymph node count in tracheobronchial adenoid cystic carcinoma

Yang Wo, Shicheng Li, Yuanyong Wang, Tong Lu, Yi Qin, Xiao Sun, Wenjie Jiao Department of Thoracic Surgery, Affiliated Hospital of Qingdao University, Qingdao, People’s Republic of China Purpose: To identify potential risk factors of lymph node metastasis and to verify the prognostic significance of the lymph node ratio (LNR) and the total number of lymph nodes examined (NNE) in tracheobronchial adenoid cystic carcinoma (ACC) patients, using a large population-based database.Patients and methods: From Surveillance, Epidemiology, and End Results database, we identified 263 patients with tracheobronchial ACC in whom complete lymph node data could be obtained. Logistic regression analysis was performed to determine predictive factors of nodal metastasis. X-tile software determined the optimal cut-off points for LNR and NNE. Kaplan–Meier analyses and Cox regression models were adopted for survival analysis.Results: Of 263 patients, 75 (28.5%) had lymph node involvement. Tumors of bronchial origin (P<0.001) and tumors larger than 30  mm (P<0.001) were associated with a higher likelihood of nodal involvement. Examination of more than ten lymph nodes could avoid understaging and resulted in improved survival; meanwhile, patients with a LNR of 0.07 or less had favorable prognosis.Conclusion: Patients with tracheobronchial ACC have significant risk of lymph node metastasis. Bronchial ACC and larger tumor size are both risk factors of lymph node metastasis. LNR and NNE may provide a more precise prediction of survival and could be taken into account in future clinical work.Keywords: adenoid cystic carcinoma, trachea, bronchus, lymph node, SEER databas