Predictors And Survival Impact Of Station 4L Metastasis In Left Non-small Cell Lung Cancer

Background and aims:Lymph node dissection(LND)is an important component in the surgical treatment of non-small cell lung cancer(NSCLC)due to its crucial role in accurate staging and prognostic implication.However,the extent of LND has partly depended on the experience of thoracic surgeons.Station 4L LND has been omitted by some surgeons because of the anatomic limitation,but it is seemed to be necessary to perform station 4L LND because of the relatively common involvement of this station lymph nodes.It remains unclear about the predictors and survival impact of station 4L metastasis in left-sided non-small cell lung cancer(NSCLC).This study aims to investigate these issues to explore the significance of station 4L lymph node dissection(LND).Methods:We retrospectively reviewed the records of all patients who underwent left NSCLC surgery in our department from January 2013 to August 2018 and ultimately enrolled 405 patients with station 4L LND and then divided them into the positive station 4L metastasis group and the negative station 4L metastasis group.The clinical and pathological characteristics were collected from the hospital electronic medical records system.The measurement data and numeration data of two groups were statistically analyzed with t test and ?2 test respectively.If there were clinicopathological characteristics showing significant differences between two groups,multivariate analysis was performed for those characteristics by the binary logistic regression to identify the factors predicting station 4L metastasis.The survival outcomes including disease-free survival(DFS)and overall survival(OS)were analyzed by the Kaplan-Meier method and the log-rank test in the subgroup of pN2 patients to explore the prognostic effect of station 4L metastasis.Univariate and multivariate Cox regression analysis were further performed to identify the independent survival factors among the different metastatic lymph node stations.Results:There were 48(11.9%)patients in the positive station 4L metastasis group and 357(88.1%)patients in the negative station 4L metastasis group.Station 5 metastasis(P=0.008,OR=7.578,95%CI=1.710-33.589),station 10 metastasis(P=0.004,OR=7.133,95%CI=1.904-26.717)and cN2(P=0.010,OR=5.062,95%CI=1.473-17.392)were independent risk factors of station 4L metastasis.In the subgroup analysis of pN2 patients,the median DFS was 17 months(95%CI=6.458-27.542)and 37 months(95%CI=16.549-57.451)in the positive station 4L metastasis group and the negative station 4L metastasis group,respectively.The median OS was 28 months(95%CI=16.971-39.029)and 54 months(95%CI=25.602-82.398)in the positive station 4L metastasis group and the negative station 4L metastasis group,respectively.The patients with station 4L metastasis group had inferior DFS(P=0.019)and OS(P=0.006)compared with those without station 4L metastasis,and station 4L metastasis was identified to be the independent risk factor for poor prognosis by Cox regression analysis.Conclusion:Station 4L metastasis is not rare and has a more unfavorable prognosis than other stations involvement,so it is of great necessity to perform station 4L LND in left NSCLC to adequately assess the status of station 4L lymph nodes.