Eighth Edition Staging of Thoracic Malignancies: Implications for the Reporting Pathologist

Our plain-English summary of Eighth Edition Staging of Thoracic Malignancies: Implications for the Reporting Pathologist, by A.G. Nicholson, M.S. Tsao, W.D. Travis, et al (Archives of Pathology & Laboratory Medicine, 2018).

The study

• Authors: A.G. Nicholson, M.S. Tsao, W.D. Travis, D.T. Patil, F. Galateau-Salle, M. Marino, S. Dacic, M.B. Beasley, K.J. Butnor, Y. Yatabe, H.I. Pass, V.W. Rusch, F.C. Detterbeck, H. Asamura, T.W. Rice, R. Rami-Porta
• Journal: Archives of Pathology & Laboratory Medicine
• Published: 2018;142(5):645-661
• Type of article: Review
• Cited by: 15 articles, as counted by NIH iCite
• Read it: PubMed · Publisher

Abstract

Context The Staging and Prognostic Factors Committee of the International Association for the Study of Lung Cancer, in conjunction with the International Mesothelioma Interest Group, the International Thymic Malignancy Interest Group, and the Worldwide Esophageal Cancer Collaboration, developed proposals for the 8th edition of their respective tumor, node, metastasis (TNM) staging classification systems. Objective To review these changes and discuss issues for the reporting pathologist. Data Sources Proposals were based on international databases of lung (N = 94 708), with an external validation using the US National Cancer Database; mesothelioma (N = 3519); thymic epithelial tumors (10 808); and epithelial cancers of the esophagus and esophagogastric junction (N = 22 654). Conclusions These proposals have been mostly accepted by the Union for International Cancer Control and the American Joint Committee on Cancer and incorporated into their respective staging manuals (2017). The Union for International Cancer Control recommended implementation beginning in January 2017; however, the American Joint Committee on Cancer has deferred deployment of the eighth TNM until January 1, 2018, to ensure appropriate infrastructure for data collection. This manuscript summarizes the updated staging of thoracic malignancies, specifically highlighting changes from the 7th edition that are relevant to pathologic staging. Histopathologists should become familiar with, and start to incorporate, the 8th edition staging in their daily reporting of thoracic cancers henceforth.

In plain English

This review article, written for pathologists on behalf of International Association for the Study of Lung Cancer committees, described the 8th edition of the tumor, node, metastasis (TNM) cancer staging rules. It covered lung cancer, mesothelioma, thymic epithelial tumors, and cancers of the esophagus and esophagogastric junction, and highlighted changes from the 7th edition. It did not study asbestos exposure. The rules it summarized were based on international databases, including 94 708 patients with lung cancer and an international mesothelioma data set. For malignant pleural mesothelioma, the article reported that pathologic staging did not demonstrate a survival difference between neighboring T categories, except T3 versus T4. T1a and T1b were merged into a single T1. The former N1 and N2 node categories were combined into N1, and the former N3 became N2. The M category was unchanged. Tumor thickness and nodular or rindlike tumor shape were associated with survival. For lung cancer, tumors over 5 cm up to 7 cm became T3, and tumors over 7 cm became T4. The authors concluded that pathologists need to use the new systems so that data are collected consistently.

We wrote this plain-English summary from the full article with the help of AI, and a second AI model checked each sentence against the article. It is not the authors' wording; the abstract and the article are their own account.

What the study did and found

• Design: review article summarizing the 8th edition TNM staging systems for thoracic cancers and their implications for pathologists
• Who was studied: No new patients were studied. The reviewed staging proposals drew on international databases: 94 708 patients with lung cancer, a mesothelioma data set (3519 per the article), more than 10 000 thymic epithelial tumor cases, and esophageal/esophagogastric junction cancers (22 654 per the abstract).
• Exposure: Not applicable. The article concerns cancer staging rules and does not discuss asbestos or any other exposure.
• Main results:
  • Mesothelioma: pathologic staging did not demonstrate a survival difference between adjacent T categories, except T3 versus T4.
  • Mesothelioma: performance improved when T1a and T1b were collapsed into a single T1.
  • Mesothelioma: tumor thickness and nodular or rindlike morphology were significantly associated with survival. They were recommended for further study rather than added to staging.
  • Mesothelioma: the 7th edition N1 and N2 categories were combined into N1, and former N3 nodes were reclassified as N2. The M category remained unchanged.
  • Lung cancer: tumors greater than 5 cm but not more than 7 cm are now T3, and tumors greater than 7 cm are T4.
  • Lung cancer: only the invasive component is used for the T size measurement in nonmucinous lung adenocarcinomas.
  • Thymic epithelial tumors: tumor size was not a useful discriminator for T category.
  • Esophageal cancer: N category is based on the number of positive regional lymph nodes: N1 (1 to 2), N2 (3 to 6), N3 (7 or more).
• The authors' conclusion: The authors concluded that the 8th edition, built from work over a decade covering more than 100 000 patients, produced staging systems that practicing pathologists need to use so that data are collected consistently.
• Limitations the authors state:
  • For thymic tumors, the T, N, and M definitions in this first version relied heavily on expert consensus.
  • Proposed lung cancer N subdivisions were not adopted because the data came only from pathologic staging and could not be validated clinically.
  • The actual impact of formalin fixation on lung cancer size and staging remains uncertain.

Topics

Medical terms in this study, explained in our Lexicon: Staging, Lung Cancer, Mesothelioma, Esophageal Cancer, Metastasis.

Related studies

• The IASLC Mesothelioma Staging Project: Proposals for the M Descriptors and for Revision of the TNM Stage Groupings in the Forthcoming (Eighth) Edition of the TNM Classification for Mesothelioma — V.W. Rusch, K. Chansky, et al. (2016)
• The IASLC Mesothelioma Staging Project: Proposals for Revisions of the N Descriptors in the Forthcoming Eighth Edition of the TNM Classification for Pleural Mesothelioma — D. Rice, K. Chansky, et al. (2016)
• Scientific Advances in Thoracic Oncology 2016 — R.A. Soo, E.C.A. Stone, et al. (2017)
• [18F]Fluorodeoxyglucose PET in Thoracic Malignancies — M.H. Vilstrup, D.A. Torigian (2014)
• COVID-19 in patients with thoracic malignancies (TERAVOLT): first results of an international, registry-based, cohort study — M.C. Garassino, J.G. Whisenant, et al. (2020)
• Chimeric Antigen Receptor (CAR) T-Cell Therapy for Thoracic Malignancies — S. Kiesgen, L. Chicaybam, et al. (2018)

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