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Editorial |

Misclassification of Lymph Nodes in Lung Cancer Staging: Can We Improve? FREE TO VIEW

Galit Aviram, MD; Marie-Pierre Revel, MD, PhD
Author and Funding Information

FINANCIAL/NONFINANCIAL DISCLOSURES: None declared.

aDepartment of Radiology, Tel Aviv Sourasky Medical Center, Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv, Israel

bDepartment of Radiology, Cochin Hospital, Paris Descartes University, Sorbonne Paris Cité, Paris, France

CORRESPONDENCE TO: Galit Aviram, MD, Department of Radiology, Tel Aviv Sourasky Medical Center, 6 Weitzman St, Tel Aviv 6423906, Israel


Copyright 2016, American College of Chest Physicians. All Rights Reserved.


Chest. 2017;151(4):733-734. doi:10.1016/j.chest.2016.10.050
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Published online

Lung cancer continues to be the leading cause of cancer-related mortality worldwide. Accurate staging with precise and universally accepted nomenclature is fundamental for estimating prognosis, selecting treatment, and conducting and reporting clinical trials internationally. Assessing the node status might be the most challenging of the tumor/node/metastasis (TNM) staging system for lung cancer.

FOR RELATED ARTICLE SEE PAGE 776

The first lymph node map was created 50 years ago by Naruke et al in Japan. It was followed by subsequent attempts to refine the anatomic descriptors, leading to the development of the American Thoracic Society map and the Mountain-Dresler modified American Thoracic Society (MD-ATS) map. The important differences between the Japanese and US lymph node maps can result in some tumors being staged as N2 by the MD-ATS map and as N1 by the Naruke map. In 1998, the International Association for the Study of Lung Cancer (IASLC) established its Lung Cancer Staging Project, which led to the development of an international lung cancer database. Analyses of that database led to creation of the seventh edition of the TNM staging system for lung cancer published in 2009, which included the IASLC lymph node map. The IASLC Staging Committee anticipated that this lymph node map would supersede all previous maps for the purposes of precision and international uniformity in nomenclature. An updated version of TNM classification is scheduled to be published in the eighth edition.

Is the IASLC lymph node map actually used in clinical practice? To what extent does it allow accurate N classification?

In this issue of CHEST, El-Sherief et al challenged real-life interpretation of the IASLC lymph node map by showing illustrative cases that deal with terminology and classification to various specialists in lung cancer management. By creating an online questionnaire which included image- and text-based cases, the authors asked members of professional societies in North America in the fields of thoracic radiology, thoracic surgery, and invasive pulmonology to name the stations and classify the N stage of the presented cases. The responses to this questionnaire revealed huge gaps between the desired optimal oncologic patient care and current daily practice. Only one-half of the respondents from all disciplines reported using the IASLC lymph node map in daily practice, whereas approximately one-third of them still use the MD-ATS system. Surprisingly, the rate of correct answers to unambiguous classifications, such as right- vs left-sided paratracheal lymph nodes, was no more than 45%, even among those using the IASLC lymph node map. When challenged by ambiguous or missing IASLC map definitions, the rates of stage misclassification (N1 vs N2, N2 vs N3, and even N vs M), which can lead to suboptimal management of patients with lung cancer, were devastatingly high (often > 50% of responders replying incorrectly in reference to the authors’ definitions). Lung specialists from Europe and Japan are not represented in this report.

How to explain such worrisome results? El-Sherief et al suggest that this failure rate is partially related to weak penetration and lack of sufficient familiarity of the updated IASLC lymph node map, which should have taken place during the 4 years since its introduction. Frankly, it may also suggest that the use of the presently proposed lymph node map is too complicated and that it requires mastering a considerable number of complicated details. Moreover, it contains ambiguous definitions and sometimes lacks detailed clarifications,, which must be applied when considering the very complex three-dimensional anatomy and lymph drainage pathways that exist within the thorax.

We congratulate El-Sherief et al for highlighting this important issue. The question that needs to be answered is how to avoid such misclassifications of lymph node staging, which is so critical for patient management. The eighth edition of the TNM staging is already about to be published, with no major changes having been suggested: it should be accompanied by more detailed clarifications of those ambiguous definitions. In addition, development of an interactive, Internet-based computerized application for correct lymph node staging that addresses the relevant questions in detail should be considered. This latter step could also assist clinicians who use a variety of maps or incorrect terms because identification of the correct anatomic location will provide the correct corresponding station classification. A computer-based fully automatic method for mediastinal lymph nodes station labeling may very well emerge as the most effective tool to standardize lymph node classification. Indeed, such a method was recently proposed and tested with promising results on chest CT data of 70 patients. Using the location information of segmented anatomic structures from a multiatlas formulation, it successfully detected enlarged mediastinal lymph nodes and labeled them according to the IASLC map.

To conclude, El-Sherief et al have demonstrated that the IASLC lymph node map is complicated and inaccurately used by an unacceptably large number of lung cancer specialists. The map needs to be simplified and clarified, and computer tools should be developed to help clinicians worldwide. Let us start working on it!

Supplementary Data

Torre L.A. .Bray F. .Siegel R.L. .Ferlay J. .Lortet-Tieulent J. .Jemal A. . Global cancer statistics, 2012. CA Cancer J Clin. 2015;65:87-108 [PubMed]journal. [CrossRef] [PubMed]
 
Detterbeck F. . Stage classification and prediction of prognosis: difference between accountants and speculators. J Thorac Oncol. 2013;8:820-822 [PubMed]journal. [CrossRef] [PubMed]
 
Naruke T. .Suemasu K. .Ishikawa S. . Lymph node mapping and curability at various levels of metastasis in resected lung cancer. J Thorac Cardiovasc Surg. 1978;76:832-839 [PubMed]journal. [PubMed]
 
Mountain C.F. .Dresler C.M. . Regional lymph node classification for lung cancer staging. Chest. 1997;111:1718-1723 [PubMed]journal. [CrossRef] [PubMed]
 
Rusch V.W. .Asamura H. .Watanabe H. .Giroux D.J. .Rami-Porta R. .Goldstraw P. . The IASLC lung cancer staging project: a proposal for a new international lymph node map in the forthcoming seventh edition of the TNM classification for lung cancer. J Thorac Oncol. 2009;4:568-577 [PubMed]journal. [CrossRef] [PubMed]
 
Detterbeck F.C. .Chansky K. .Groome P. .et al The IASLC Lung Cancer Staging Project: Methodology and Validation Used in the Development of Proposals for Revision of the Stage Classification of NSCLC in the Forthcoming (Eighth) Edition of the TNM Classification of Lung Cancer. J Thorac Oncol. 2016;11:1433-1446 [PubMed]journal. [CrossRef] [PubMed]
 
El-Sherief A.H. .Lau C.T. .Obuchowski N.A. .Mehta A.C. .Rice T.W. .Blackstone E.H. . Cross-disciplinary analysis of lymph node classification in lung cancer on CT scanning. Chest. 2017;151:776-785 [PubMed]journal
 
El-Sherief A.H. .Lau C.T. .Wu C.C. .Drake R.L. .Abbott G.F. .Rice T.W. . International association for the study of lung cancer (IASLC) lymph node map: radiologic review with CT illustration. Radiographics. 2014;34:1680-1691 [PubMed]journal. [CrossRef] [PubMed]
 
Kim J.H. .van Beek E.J. .Murchison J.T. .Marin A. .Mirsadraee S. . The International Association for the Study of Lung Cancer Lymph Node Map: a radiologic atlas and review. Tuberc Respir Dis (Seoul). 2015;78:180-189 [PubMed]journal. [CrossRef] [PubMed]
 
Kim A.W. . Lymph node drainage patterns and micrometastasis in lung cancer. Semin Thorac Cardiovasc Surg. 2009;21:298-308 [PubMed]journal. [CrossRef] [PubMed]
 
Asamura H. .Chansky K. .Crowley J. . International Association for the Study of Lung Cancer Lung Cancer Staging and Prognostic Factors Committee, Advisory Board Members, and Participating Institutionset al The International Association for the Study of Lung Cancer Lung Cancer Staging Project: proposals for the revision of the N descriptors in the forthcoming 8th edition of the TNM Classification for Lung Cancer. J Thorac Oncol. 2015;10:1675-1684 [PubMed]journal. [CrossRef] [PubMed]
 
Liu J. .Hoffman J. .Zhao J. .et al Mediastinal lymph node detection and station mapping on chest CT using spatial priors and random forest. Med Phys. 2016;43:4362- [PubMed]journal. [CrossRef] [PubMed]
 

Figures

Tables

References

Torre L.A. .Bray F. .Siegel R.L. .Ferlay J. .Lortet-Tieulent J. .Jemal A. . Global cancer statistics, 2012. CA Cancer J Clin. 2015;65:87-108 [PubMed]journal. [CrossRef] [PubMed]
 
Detterbeck F. . Stage classification and prediction of prognosis: difference between accountants and speculators. J Thorac Oncol. 2013;8:820-822 [PubMed]journal. [CrossRef] [PubMed]
 
Naruke T. .Suemasu K. .Ishikawa S. . Lymph node mapping and curability at various levels of metastasis in resected lung cancer. J Thorac Cardiovasc Surg. 1978;76:832-839 [PubMed]journal. [PubMed]
 
Mountain C.F. .Dresler C.M. . Regional lymph node classification for lung cancer staging. Chest. 1997;111:1718-1723 [PubMed]journal. [CrossRef] [PubMed]
 
Rusch V.W. .Asamura H. .Watanabe H. .Giroux D.J. .Rami-Porta R. .Goldstraw P. . The IASLC lung cancer staging project: a proposal for a new international lymph node map in the forthcoming seventh edition of the TNM classification for lung cancer. J Thorac Oncol. 2009;4:568-577 [PubMed]journal. [CrossRef] [PubMed]
 
Detterbeck F.C. .Chansky K. .Groome P. .et al The IASLC Lung Cancer Staging Project: Methodology and Validation Used in the Development of Proposals for Revision of the Stage Classification of NSCLC in the Forthcoming (Eighth) Edition of the TNM Classification of Lung Cancer. J Thorac Oncol. 2016;11:1433-1446 [PubMed]journal. [CrossRef] [PubMed]
 
El-Sherief A.H. .Lau C.T. .Obuchowski N.A. .Mehta A.C. .Rice T.W. .Blackstone E.H. . Cross-disciplinary analysis of lymph node classification in lung cancer on CT scanning. Chest. 2017;151:776-785 [PubMed]journal
 
El-Sherief A.H. .Lau C.T. .Wu C.C. .Drake R.L. .Abbott G.F. .Rice T.W. . International association for the study of lung cancer (IASLC) lymph node map: radiologic review with CT illustration. Radiographics. 2014;34:1680-1691 [PubMed]journal. [CrossRef] [PubMed]
 
Kim J.H. .van Beek E.J. .Murchison J.T. .Marin A. .Mirsadraee S. . The International Association for the Study of Lung Cancer Lymph Node Map: a radiologic atlas and review. Tuberc Respir Dis (Seoul). 2015;78:180-189 [PubMed]journal. [CrossRef] [PubMed]
 
Kim A.W. . Lymph node drainage patterns and micrometastasis in lung cancer. Semin Thorac Cardiovasc Surg. 2009;21:298-308 [PubMed]journal. [CrossRef] [PubMed]
 
Asamura H. .Chansky K. .Crowley J. . International Association for the Study of Lung Cancer Lung Cancer Staging and Prognostic Factors Committee, Advisory Board Members, and Participating Institutionset al The International Association for the Study of Lung Cancer Lung Cancer Staging Project: proposals for the revision of the N descriptors in the forthcoming 8th edition of the TNM Classification for Lung Cancer. J Thorac Oncol. 2015;10:1675-1684 [PubMed]journal. [CrossRef] [PubMed]
 
Liu J. .Hoffman J. .Zhao J. .et al Mediastinal lymph node detection and station mapping on chest CT using spatial priors and random forest. Med Phys. 2016;43:4362- [PubMed]journal. [CrossRef] [PubMed]
 
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