The Impact of the Eighth TNM Classification for Lung Cancer on the Endobronchial Ultrasound Procedure
Authors: Hussein Assallum, Kassem Harris
Journal: Journal of Thoracic Oncology (2018)

Major changes in lung cancer staging were reported in the new eight TNM classification.1Rami-Porta R. Asamura H. Travis W.D. Rusch V.W. Lung cancer—major changes in the American Joint Committee on Cancer eighth edition cancer staging manual.CA Cancer J Clin. 2017; 67: 138-155Crossref PubMed Scopus (206) Google Scholar The bronchoscopist should adapt to these changes to provide the most comprehensive lung cancer staging, which will be an important determinant of the management strategy. In the new TNM classification, the nodal staging was not changed from the seventh TNM classification.2Detterbeck F.C. Boffa D.J. Kim A.W. Tanoue L.T. The eighth edition lung cancer stage classification.Chest. 2017; 151: 193-203Abstract Full Text Full Text PDF PubMed Scopus (818) Google Scholar However, many suggestions related to nodal staging were highlighted and are of significant relevance for the appropriate staging of lung cancer. Pathologic nodal staging has shown that the more involved stations, the worse the prognosis. Interestingly, patients with lung cancer with N1b (N1 multiple) and N2a1 (N2 single with skip metastasis) disease have similar prognoses, with 5-year survival rates after resection of 50% and 54%, respectively, for R0 settings (no residual tumor) and 50% and 52%, respectively, for any R settings (presence of residual tumor after resection). Patients with lung cancer and N2a2 disease (single N2 nodal station with N1 involvement) have a significantly worse prognosis than do those with N2a1 disease, with 5-year survival rates of 43% and 54%, respectively.3Asamura H. Chansky K. Crowley J. et al.The International Association for the Study of Lung Cancer Lung Cancer Staging Project: proposals for the revisions of the N descriptors in the forthcoming 8th edition of the TNM classification for lung cancer.J Thorac Oncol. 2015; 10: 1675-1684Abstract Full Text Full Text PDF PubMed Scopus (443) Google Scholar Endobronchial ultrasound–guided transbronchial needle aspiration (EBUS TBNA) is the procedure of choice for staging NSCLC.4Wahidi M.M. Herth F. Yasufuku K. Shepherd R.W. et al.Technical aspects of endobronchial ultrasound-guided transbronchial needle aspiration: CHEST guideline and expert panel report.Chest. 2016; 149: 816-835Abstract Full Text Full Text PDF PubMed Scopus (259) Google Scholar During the EBUS TBNA procedure, the N3 lymph node stations are sampled first, followed by the N2 then N1 lymph node stations.5Kinsey C.M. Arenberg D.A. Endobronchial ultrasound-guided transbronchial needle aspiration for non-small cell lung cancer staging.Am J Respir Crit Care Med. 2014; 189: 640-649Crossref PubMed Scopus (90) Google Scholar The EBUS TBNA procedure for NSCLC staging should be adapted to the new TNM classification changes. When rapid on-site evaluation is used, a positive N3 station makes the patient stage IIIB and there is no need to sample the N2 or N1 stations, considering that enough specimens are taken for molecular testing. If the N3 stations are negative, the N2 stations should be sampled. If the first sampled N2 station is positive, the other N2 stations should be sampled and the EBUS needle should be changed to prevent tissue contamination and false declaration that the patient has N2b (multiple N2 stations) disease.6Ernst A. Feller-Kopman D. Herth F.J. Endobronchial ultrasound in the diagnosis and staging of lung cancer and other thoracic tumors.Semin Thorac Cardiovasc Surg. 2007; 19: 201-205Abstract Full Text Full Text PDF PubMed Scopus (19) Google Scholar If two or more N2 stations are positive, the nodal staging will be N2b and the EBUS procedure can be concluded without any need to sample the N1 node stations. However, if only one N2 station is positive, sampling the N1 node stations becomes important to differentiate between N2a2 and N2a1 nodal staging. Previously, the procedure could be concluded after the finding of positive N2 stations and there would be no need to sample the N1 lymph nodes. It is also imperative to change the EBUS needle before sampling the N1 stations to prevent sample contamination after the malignant N2 lymph node station. When rapid on-site evaluation is not available, all stations should be sampled and the EBUS needle should be changed between the different N2 stations and when moving from the last N2 station sampled and N1 lymph node stations.7Berim I. Colanta A. Saeed A. et al.Contamination of needles used for endobronchial ultrasound guided biopsies: myth confirmed.Am J Respir Crit Care Med. 2017; 195: A2868Google Scholar Although the nodal staging has not changed, the quantification by the number of nodes involved with cancer is a new addition in the eighth TNM lung cancer staging classification and should be adopted in the pathologic lymph nodes staging by EBUS TBNA.