Chest
Volume 151, Issue 4, April 2017, Pages 776-785
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Original Research: Lung Cancer
Cross-Disciplinary Analysis of Lymph Node Classification in Lung Cancer on CT Scanning

https://doi.org/10.1016/j.chest.2016.09.016Get rights and content

Background

Accurate and consistent regional lymph node classification is an important element in the staging and multidisciplinary management of lung cancer. Regional lymph node definition sets—lymph node maps—have been created to standardize regional lymph node classification. In 2009, the International Association for the Study of Lung Cancer (IASLC) introduced a lymph node map to supersede all preexisting lymph node maps. Our aim was to study if and how lung cancer specialists apply the IASLC lymph node map when classifying thoracic lymph nodes encountered on CT scans during lung cancer staging.

Methods

From April 2013 through July 2013, invitations were distributed to all members of the Fleischner Society, Society of Thoracic Radiology, General Thoracic Surgical Club, and the American Association of Bronchology and Interventional Pulmonology to participate in an anonymous online image-based and text-based 20-question survey regarding lymph node classification for lung cancer staging on CT imaging.

Results

Three hundred thirty-seven people responded (approximately 25% participation). Respondents consisted of self-reported thoracic radiologists (n = 158), thoracic surgeons (n = 102), and pulmonologists who perform endobronchial ultrasonography (n = 77). Half of the respondents (50%; 95% CI, 44%-55%) reported using the IASLC lymph node map in daily practice, with no significant differences between subspecialties. A disparity was observed between the IASLC definition sets and their interpretation and application on CT scans, in particular for lymph nodes near the thoracic inlet, anterior to the trachea, anterior to the tracheal bifurcation, near the ligamentum arteriosum, between the bronchus intermedius and esophagus, in the internal mammary space, and adjacent to the heart.

Conclusions

Use of older lymph node maps and inconsistencies in interpretation and application of definitions in the IASLC lymph node map may potentially lead to misclassification of stage and suboptimal management of lung cancer in some patients.

Section snippets

Methods

From April 2013 through July 2013, all members of the Fleischner Society, Society of Thoracic Radiology, General Thoracic Surgical Club, and the American Association of Bronchology and Interventional Pulmonology were invited to participate in an anonymous online 20-question image-based and text-based survey on lymph node classification for lung cancer staging on CT images. The survey was distributed using SurveyGizmo, a commercial online survey tool (Widgix, LLC dba SurveyGizmo). Cookie-based

Results

Complete responses were submitted by 337 individuals, representing approximately 25% participation. Respondents self-reported themselves as thoracic radiologists (n = 158), thoracic surgeons (n = 102), and pulmonologists who perform endobronchial ultrasonography (n = 77). Most respondents (89% [300 of 337]) practiced in North America.

Principal Findings

Our study reveals that 4 years after its introduction, the IASLC lymph node map is used by approximately 50% of thoracic radiologists, approximately 50% of thoracic surgeons, and approximately 50% of pulmonologists who perform endobronchial ultrasonography.

For lung cancer specialists who use the IASLC lymph node map, a disparity exists between the IASLC definition sets, their interpretation, and their application on CT imaging, in particular for lymph nodes (1) near the thoracic inlet, (2)

Conclusions

The presence of inconsistencies in lymph node classification among lung cancer specialists indicates that a universally implemented regional thoracic lymph node map has not yet been realized. One reason may be that lymph node stations are traditionally defined using anatomic textual descriptions that require an additional layer of interpretation before use in the operating room, bronchoscopy suite, or radiology reading room. The inconsistencies, ambiguities, and unpredictability introduced by

Acknowledgments

Author contributions: A. H. E-S. had full access to all the data in the study and takes responsibility for the integrity of the data and the accuracy of the data analysis, including and especially any adverse effects. A. H. E-S., C. T. L., N. A. O., A. C. M., T. W. R., and E. H. B. contributed substantially to the study design/implementation, data analysis and interpretation, and writing of the manuscript.

Financial/nonfinancial disclosures: None declared.

Other contributions: The authors

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FUNDING/SUPPORT: The authors have reported to CHEST that no funding was received for this study.

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