Invited Commentary

Abstract

Osarogiagbon and colleagues [1Osarogiagbon R.U. Ogbata O. Yu X. Number of lymph nodes associated with maximal reduction of long-term mortality risk in pathologic node-negative non-small cell lung cancer.Ann Thorac Surg. 2014; 97: 385-393Abstract Full Text Full Text PDF PubMed Scopus (102) Google Scholar] have analyzed non-small cell lung cancer (NSCLC) resections in the Surveillance, Epidemiology, and End Results (SEER) database between 1998 and 2009 and found that 13% of resections were performed without any lymph node staging (pNX) [2Osarogiagbon R.U. Allen J.W. Farooq A. et al.Pathologic lymph node staging practice and stage-predicted survival after resection of lung cancer.Ann Thorac Surg. 2011; 91: 1486-1493Abstract Full Text Full Text PDF PubMed Scopus (34) Google Scholar, 3Osarogiagbon R.U. Allen J.W. Farooq A. et al.Objective review of mediastinal lymph node examination in a lung cancer resection cohort.J Thorac Oncol. 2012; 7: 390-396Crossref PubMed Scopus (56) Google Scholar, 4Osarogiagbon R.U. Yu X. Mediastinal lymph node examination and survival in resected early-stage non-small cell lung cancer in the Surveillance, Epidemiology, and End Results database.J Thorac Oncol. 2012; 7: 1798-1806Crossref PubMed Scopus (86) Google Scholar, 5Osarogiagbon R.U. Miller L.E. Ramirez R.A. et al.Use of a surgical specimen-collection kit to improve mediastinal lymph-node examination of resectable lung cancer.J Thorac Oncol. 2012; 7: 1276-1282Crossref PubMed Scopus (33) Google Scholar, 6Osarogiagbon R.U. Yu X. Nonexamination of lymph nodes and survival after resection of non-small cell lung cancer.Ann Thorac Surg. 2013; 96: 1178-1189Abstract Full Text Full Text PDF PubMed Scopus (66) Google Scholar]. Patients with NSCLC who had no clinical evidence of nodal disease but were pNX had a 5-year survival similar those with pN1 tumors, suggesting significant understaging at the time of operation. Using the same SEER dataset, they now focus on pathologically node-negative NSCLC (pT1-3N0) to assess the number of lymph nodes that should be removed to achieve optimal staging. They identify six as the minimum number of lymph nodes that should be removed and 20 as the number associated with the lowest mortality risk (and therefore the optimal number) across all tumor T categories.The advantages of the SEER dataset are the large number of cases available for analysis and the fact that it reflects the daily realities of clinical practice across geographically diverse patient populations. However, it includes a wide range of surgical and pathologic practice and does not provide the level of detail available from more focused surgical series. Twenty lymph nodes presumes an extensive removal of N1 and N2 nodes, but the results of this study do not clarify the relative importance of the number of lymph nodes resected versus the number or location of lymph stations sampled. This study also cannot clarify whether such an extensive retrieval of lymph nodes is necessary for very early lung cancers, including those measuring less than 2 cm in size or adenocarcinomas that have a lepidic predominant pattern. These are critical issues that require further study as the American Joint Commission on Cancer and the International Union Against Cancer move toward the 8th edition of their staging manuals (to be published in 2016) which will provide guidelines for adequate surgical and pathological staging of NSCLC. However, Osarogiagbon and colleagues have again highlighted the importance of adequate lymph node removal in the management of resectable NSCLC and the presence of a quality gap in clinical care that needs to be rectified. Osarogiagbon and colleagues [1Osarogiagbon R.U. Ogbata O. Yu X. Number of lymph nodes associated with maximal reduction of long-term mortality risk in pathologic node-negative non-small cell lung cancer.Ann Thorac Surg. 2014; 97: 385-393Abstract Full Text Full Text PDF PubMed Scopus (102) Google Scholar] have analyzed non-small cell lung cancer (NSCLC) resections in the Surveillance, Epidemiology, and End Results (SEER) database between 1998 and 2009 and found that 13% of resections were performed without any lymph node staging (pNX) [2Osarogiagbon R.U. Allen J.W. Farooq A. et al.Pathologic lymph node staging practice and stage-predicted survival after resection of lung cancer.Ann Thorac Surg. 2011; 91: 1486-1493Abstract Full Text Full Text PDF PubMed Scopus (34) Google Scholar, 3Osarogiagbon R.U. Allen J.W. Farooq A. et al.Objective review of mediastinal lymph node examination in a lung cancer resection cohort.J Thorac Oncol. 2012; 7: 390-396Crossref PubMed Scopus (56) Google Scholar, 4Osarogiagbon R.U. Yu X. Mediastinal lymph node examination and survival in resected early-stage non-small cell lung cancer in the Surveillance, Epidemiology, and End Results database.J Thorac Oncol. 2012; 7: 1798-1806Crossref PubMed Scopus (86) Google Scholar, 5Osarogiagbon R.U. Miller L.E. Ramirez R.A. et al.Use of a surgical specimen-collection kit to improve mediastinal lymph-node examination of resectable lung cancer.J Thorac Oncol. 2012; 7: 1276-1282Crossref PubMed Scopus (33) Google Scholar, 6Osarogiagbon R.U. Yu X. Nonexamination of lymph nodes and survival after resection of non-small cell lung cancer.Ann Thorac Surg. 2013; 96: 1178-1189Abstract Full Text Full Text PDF PubMed Scopus (66) Google Scholar]. Patients with NSCLC who had no clinical evidence of nodal disease but were pNX had a 5-year survival similar those with pN1 tumors, suggesting significant understaging at the time of operation. Using the same SEER dataset, they now focus on pathologically node-negative NSCLC (pT1-3N0) to assess the number of lymph nodes that should be removed to achieve optimal staging. They identify six as the minimum number of lymph nodes that should be removed and 20 as the number associated with the lowest mortality risk (and therefore the optimal number) across all tumor T categories. The advantages of the SEER dataset are the large number of cases available for analysis and the fact that it reflects the daily realities of clinical practice across geographically diverse patient populations. However, it includes a wide range of surgical and pathologic practice and does not provide the level of detail available from more focused surgical series. Twenty lymph nodes presumes an extensive removal of N1 and N2 nodes, but the results of this study do not clarify the relative importance of the number of lymph nodes resected versus the number or location of lymph stations sampled. This study also cannot clarify whether such an extensive retrieval of lymph nodes is necessary for very early lung cancers, including those measuring less than 2 cm in size or adenocarcinomas that have a lepidic predominant pattern. These are critical issues that require further study as the American Joint Commission on Cancer and the International Union Against Cancer move toward the 8th edition of their staging manuals (to be published in 2016) which will provide guidelines for adequate surgical and pathological staging of NSCLC. However, Osarogiagbon and colleagues have again highlighted the importance of adequate lymph node removal in the management of resectable NSCLC and the presence of a quality gap in clinical care that needs to be rectified. Number of Lymph Nodes Associated With Maximal Reduction of Long-Term Mortality Risk in Pathologic Node-Negative Non–Small Cell Lung CancerThe Annals of Thoracic SurgeryVol. 97Issue 2PreviewForty-four percent of patients with pathologic node negative (pN0) non–small cell lung cancer (NSCLC) die within 5 years of curative-intent surgical procedures. Heterogeneity in pathologic nodal examination practice raises concerns about the accuracy of nodal staging in these patients. We hypothesized a reciprocal relationship between the number of lymph nodes examined and the probability of missed lymph node metastasis and sought to identify the number of lymph nodes associated with the lowest mortality risk in pN0 NSCLC. Full-Text PDF