A Brief Analysis Of Intrathoracic Lymph Nodes Metastasis Rules In Non-small Cell Lung Cancer

Objective:Investigating the relationship between the size of tumor(T), location ofprimary tumor, central/peripheral, histopathological types, carcino-embryonic antigen(CEA) and intrathoracic lymph nodes metastasis in non-small cell lung cancer;Analyzing the basic rules and distribution characteristics of intrathoracic lymph nodesmetastasis. So as to provide an important clinical evidence for lymph node dissection,improve the cleaning rate of positive lymph nodes, postoperative pathologic staging andguide postoperative comprehensive therapy reasonably.Methods:Collecting medical records of173patients with non-small cell lung cancerunderwent surgical treatment in affiliated hospital of Yan’an university from Jan2010toDec2010. All information about these patients were retrospectively analyzed.Lobectomy/pneumonectomy＋SMLND was performed on173patients. The dissectedlymph nodes were grouped by the new intrathoracic lymph nodes distribution standardproposed by International Association for the Study of Lung Cancer(IASLC), thenmarked and done routine pathological specimens analysis respectively. Thepostoperative pathological stage was according to the new TNM staging standardspresented by IASLC. Collecting and recording the preoperative value of CEA, the size oftumor(T), location of primary tumor, histopathological types, central/peripheral and thestatus of the dissected and metastasising intrathoracic lymph nodes. All cases weregrouped by the size of tumor(T), location of primary tumor, central/peripheral,histopathological types and the value of CEA respectively, analyzed metastaicdistribution rules and characteristics of lymph nodes.Results:A total number of948groups,2388intrathoracic lymph nodes were dissected in173cases of NSCLC patients during operation; metastasis occurred in209groups,458lymph nodes, and were confirmed by pathological test. The rate of skip metastasis（pureN2metastasis）was11.0%, and total metastasis rate of the lymph nodes was52.6%in173cases of NSCLC patients. The metastasis rate of the4,5,6,7,10and11groups were19.8%,27.3%,19.4%,27.3%,35.5%and31.4%. There was statistically significantdifference in the metastasis rates of intrathoracic lymph nodes between T1、T2、T3and T4patients(P <0.01).There was no statistically significant difference in the transfer ratesof N2lymph nodes among of each lobe(P>0.05). The difference of N2lymph nodesmetastasis rate between upper lobe and lower lobe has statistical significance (P <0.05).The difference of the lymph node metastasis rate between central and peripheral NSCLChas statistical significance(P <0.01); The difference of N1and N2nodal metastasis ratebetween two groups was statistical significance (P <0.05). The difference ofintrathoracic lymph node metastasis rate between adenocarcinoma and squamous cellcarcinomas has statistical significance (P <0.017). The difference of intrathoracic lymphnode metastasis rate between the high and normal CEA group has statistical significance(P <0.01). The metastasis rate of lymph node was72.0%in the high CEA group ofadenocarcinoma, the metastasis rate of lymph node was55.8%in the high CEA group ofsquamous cell carcinomas, the difference was statistically significant(P <0.05); thedifference of N2metastasis lymph node metastasis rate between the high and normalvalue of CEA in each groups has statistical significance(P <0.05).Conclusions:The incidence of intrathoracic lymph node metastasis had a certainrelationship with the size of tumor(T), location of primary tumor, central/peripheral,histopathological types and the value of CEA. The metastatic incidences in groups closedto the hilar were than those of regions far from hilar. With the increase of the tumor sizeand outer invasion scope, the possibility of intrathoracic lymph node metastasis wasincreased. N2lymph node metastasis have the same probability in each lung lobe, thegroup of7thlymph node is the intersection connecting N2lymph node in the upper andlower mediastinum; Tumors located in the upper lobe has a tendency of metastasis to N2 lymph node in the upper mediastinum frequently, while tumors located in the lower lobehad a tendency of metastasis to the upper and lower mediastinum. Intrathoracic lymphnode of central NSCLC occurred metastasis more easily than peripheral NSCLC, thecentral type often occurred N2lymph node metastasis, while the peripheral is N1lymphnode. The rate of lymph node metastasis were different in each histopathological types,adenocarcinoma is more likely to occur lymph node metastasis. Betweenadenocarcinoma and squamous cell carcinomas, the high CEA NSCLC has an higherpossibility of lymph node metastasis than those in normal CEA, the former occurredmore skip metastasis. Intrathoracic lymph node metastasis of NSCLC has acharacteristics of multiple, jumping, area and trans-region. Therefor, SMLND isnecessary during operation, it can improve the cleaning rate of positive lymph nodes,postoperative pathologic staging and guide postoperative comprehensive therapyreasonably.