The Significance Of Subcarinal Lymph Node Dissection And Prognostic Factor Analysis In Middle And Lower Thoracic Esophageal Squamous Cell Carcinoma

Objective: Esophageal cancer is one of the most common gastrointestinal tumors in China.However,the range of lymph node dissection during surgery has always been the focus of controversy.In the UICC guidelines,the number of positive lymph nodes was used for the N staging standard,and the number of lymph nodes dissected should be no less than 15.However,the lymphatic network for the esophagus is abundant,and lymph node metastasis is easy to occur even in the early stage of esophageal cancer.Thus,there are many limitations to define N stages simply by the number of positive lymph nodes.For instance,the prognosis of the patients could be different if the positive lymph nodes gathered in one area or distributed in different areas.Therefore,some Japanese researchers suggested that lymph nodes should be dissected according to the lymph node metastasis patterns of esophageal cancer.However,these two methods of dissection have their own advantages and disadvantages,and consequently,there is no consensus on how to dissect the lymph nodes of esophageal cancer intraoperatively.In this study,the significance of subcarinal lymph dissection and prognostic factor of middle and lower thoracic esophageal cancer were analyzed to preliminary investigate the ranges of lymph nodes dissection for esophageal cancer.Methods: Data of patients underwent esophagectomy for middle and lower thoracic esophageal squamous cell carcinoma from Jan.2008 to Jan.2014 in the Fourth Hospital of Hebei Medical University were collected in this retrospective study.All patients did not receive preoperative adjuvant therapy(radiotherapy,chemotherapy)and distant metastasis disease were excluded.Postoperative pathology analysis confirmed the diagnosis of squamous cell carcinoma in the middle and lower thoracic esophagus.All patients underwent radical resection of esophageal cancer,and the number of intraoperative dissected lymph nodes were no less than 7.Gender,age,smoking history,drinking history,tumor location,tumor size,tumor infiltration depth,positive lymph node number,degree of tumor differentiation,number of dissected lymph nodes,subcarinal lymph nodes dissection situation,stump invasion,vascular invasion situation,survival time,time to progression,and cause of death were collected.1588 patients,including 198 patients without the subcarinal lymph node dissection were recruited.SPSS statistical software 23.0 was used to analyze the gender,age,tumor location,tumor length to diameter,the number of positive lymph nodes,tumor infiltration depth,number of lymph node dissected,history of smoking,history of drinking,stump invasion,vascular invasion,postoperative adjuvant therapy situation using PSM method.Calipers value was 0.05.198 patients without subcarinal lymph node dissection and 1390 patients with subcarinal lymph node ssection were matched by 1:3 near-neighbor matching method.185 patients without subcarinal lymph node dissection were successfully matched with 476 patients subcarinal lymph node dissection,and a total of 661 patients were included in this study.Kaplan-Meier survival curve and log-rank test were used for univariate survival analysis.Cox regression method was used for multivariate survival analysis,and chi-square test was used for counting data.The test level was bilateral =0.05.When P < 0.05,statistical difference was considered to be significance.Prognostic factors were analyzed including including gender,age,tumor location,tumor length to diameter,the number of positive lymph nodes,tumor infiltration depth,the degree of tumor differentiation,number of lymph node dissection,history of smoking and drinking,stump invasion situation,vascular invasion situation,subcarinal lymph node dissection situation,and the risk factors of the subcarinal lymph node metastasis were estimated.Results: Up to the follow-up date,the 3-year and 5-year OS of 661 patients with middle and lower thoracic esophageal squamous cell carcinoma in the whole group was 57.0% and 44.3%,respectively.The median value was 49 months(rang from 1 to 117 months),and both univariate and multivariate analyses showed that the presence or absence of subcarinal lymph nodes dissection was not a factor affecting OS in mid-lower thoracic esophageal squamous cell carcinoma.Further stratified analysis showed that the presence or absence of dissected subcarinal lymph nodes in stage T3 was associated with OS(P=0.014 < 0.05).The 3-year and 5-year DFS of 661 patients with middle and lower thoracic esophageal squamous cell carcinoma were 53.4% and 39.2%,respectively.The median value was 42 months(ranging from 1 to 117 months),and both univariate and multivariate analyses showed that the presence or absence of subcarinal lymph node dissection was not a factor affecting DFS in mid-to-lower thoracic esophageal squamous cell carcinoma.Further stratified analysis showed that DFS was correlated with the presence or absence of dissected subcarinal lymph nodes in stage T3(P=0.024 < 0.05).A total of 476 patients had their subcarinal lymph nodes dissected,and 49 patients had positive subcarinal lymph nodes,with a lymph node metastasis rate of 10.3%.A total of 1592 subcarinal lymph nodes were dissected,70 of which were positive,and the degree of lymph node metastasis was 4.4%.Univariate analysis showed that tumor length and diameter,tumor invasion depth,number of positive lymph nodes,smoking history and drinking history were related to subcarinal lymph node metastasis.Multivariate logistic regression analysis showed that the depth of tumor invasion and the number of positive lymph nodes were high risk factors for subcarinal lymph node metastasis.Conclusion:1 Gender,length of lesion,depth of infiltration,number of positive lymph nodes,number of lymph nodes dissected,and presence or absence of postoperative adjuvant treatment are independent factors affecting OS and DFS in patients with mid-lower thoracic esophageal squamous cell carcinoma.2 Subcarinal lymph node dissection can improve OS and DFS for patients with stage T3 esophageal cancer.Therefore,it is recommended for cancer invading fibrous membrane or beyond.