Editorial Comment
Cardiothoracic Imaging
June 7, 2023

Editorial Comment: Prognostic Implications of CT-Defined Extranodal Extension of Metastatic Lymph Nodes in Patients With Non–Small Cell Lung Cancer

A major component in the lung cancer TNM staging system is the status of lymph node (LN) involvement, and accurate LN assessment is crucial in patient management. The N component is currently stratified into categories of N0 to N3 solely on the basis of the anatomic stations with metastatic LN involvement. Options for revising the N classification include counting LNs, LN stations, or LN zones, as well as detecting extranodal extension (ENE) [1].
For metastatic LNs, ENE is defined as extension of metastatic cells beyond the LN capsule into perinodal tissue. ENE has been incorporated into N category determination for head and neck cancers and for vulvar cancer. In a meta-analysis of pathologic ENE in patients with non–small cell lung cancer (NSCLC), ENE was associated with poor prognosis in terms of disease recurrence and all-cause mortality [2].
This retrospective study of 382 patients with NSCLC investigated prognostic implications of CT-based ENE and the diagnostic performance of CT-based ENE in predicting pathologic ENE. Indistinct LN margin, coalescent LNs, direct invasion of adjacent structures, and central necrosis were found to be possible CT findings of ENE. These findings were adopted from previously explored CT findings of ENE in head and neck cancer [3]. Two chest radiologists also classified CT examinations for overall confidence in presence of ENE on a patient level as no ENE, possible or probable ENE, and unambiguous ENE. For both readers, 5-year overall survival rates were significantly different among these three tiers. Unambiguous ENE independently predicted worse overall survival and was highly specific in predicting pathologic ENE.
This is the first study, to my knowledge, to evaluate the impact of CT-based ENE in predicting prognosis and pathologic ENE. Although identifying ENE on CT is challenging, this study opens a new window into CT-based evaluation for ENE of metastatic LNs in NSCLC.


Provenance and review: Solicited; not externally peer reviewed.


Osarogiagbon RU, Van Schil P, Giroux DJ, et al.; Members of the N-Descriptors Subcommittee. The International Association for the Study of Lung Cancer lung cancer staging project: overview of challenges and opportunities in revising the nodal classification of lung cancer. J Thorac Oncol 2023; 18:410–418
Luchini C, Veronese N, Nottegar A, et al. Extranodal extension of nodal metastases is a poor prognostic moderator in non-small cell lung cancer: a meta-analysis. Virchows Arch 2018; 472:939–947
Chai RL, Rath TJ, Johnson JT, et al. Accuracy of computed tomography in the prediction of extracapsular spread of lymph node metastases in squamous cell carcinoma of the head and neck. JAMA Otolaryngol Head Neck Surg 2013; 139:1187–1194

Information & Authors


Published In

American Journal of Roentgenology
Pages: 485
PubMed: 37459482


Version of record online: June 7, 2023



Jin Mo Goo, MD, PhD
Seoul National University Hospital, Cancer Research Institute, Seoul National University, Seoul, Korea, [email protected]


Version of record: Aug 16, 2023
The author declares that there are no disclosures relevant to the subject matter of this article.

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