For many years to come, surgery will remain the only curative treatment for non-small-cell lung cancer in early disease stages, and for as many years, the preoperative staging of mediastinal lymph nodes will remain central to the decision whether a patient should undergo surgery or not.

The staging methods have changed considerably with the advent of whole-body FDG-PET scan [1], which can now be combined with chest CT scans [2]. The imaging techniques for the mediastinum, however, are still limited in their sensitivity and specificity. The CT size criteria for mediastinal nodes have long been questioned [3], because inflammatory lymph node enlargements should not exclude patients from the opportunity of curative resection. Metabolic information from FDG-PET, on the other hand, can also show positive signals in inflammatory lymph nodes.

Even with this combined information, however, false-positive and false-negative results occur. In the light of the importance of correct mediastinal staging in non-small-cell lung cancer, where missing a possible resection means missing a chance to cure the patient, we still need cytologic or histologic confirmation of decisive mediastinal node involvement. Clearly, the method of choice, the gold standard, is mediastinoscopy, which allows for the histologic assessment of the most important mediastinal node locations. Although a relatively safe surgical procedure, mediastinoscopy is still an intervention requiring general anaesthesia and an experienced chest surgeon. So, the goal is to avoid unnecessary mediastinoscopies where possible.

Today, no resection of lung cancer should be performed without previous flexible bronchoscopy. This is usually the method of choice for the preoperative histologic assessment of the primary tumour. During the same session, transbronchial needle aspiration (TBNA) techniques allow assessment of the involvement of the most important mediastinal lymph node locations in the paratracheal and tracheobronchial as well as infracarinal locations. If interpreted with caution (lymphocytes need to be in the specimen in order to exclude contamination of the sample with bronchial secretions, which may potentially contain tumour cells), false-positive cytologic results are extremely rare [4]. In experienced hands, this technique is safe and requires little time (a few minutes per location). The negative predictive value has only rarely been assessed, but may be as high as 80% (personal experience). Even with a sensitivity of only 65% (in the study by Hermens et al., this issue of Respiration [5]), there is still a relevant number of mediastinoscopies that can be omitted in TBNA-diagnosed N3 disease. In addition, TBNA adds to the overall diagnostic yield of flexible bronchoscopy. If the histology needle is used, which may be a little harder to push through the bronchial wall, this relates not only to the diagnosis of cancers, but also to benign diseases, such as sarcoidosis, tuberculosis or lymphomas.

Contralateral lymph node involvement proven by TBNA still means inoperability if TBNA was performed with a staging concept in mind, beginning with the node most distant from the primary tumour. Infracarinal or ipsilateral involvement is more difficult to weigh up in the clinical context. If the patient is to undergo neoadjuvant chemotherapy for N2 disease, based on a positive cytology only, it will never become clear if there had been microscopic involvement of the contralateral N3 nodes, which would still exclude a patient from this therapeutic strategy. I would, therefore, strongly advocate performing a mediastinoscopy before neoadjuvant chemotherapy in N2 disease, even if the available staging information includes an FDG-PET compatible with TBNA cytology and CT scan. With the development of new neoadjuvant chemo- and radiotherapy concepts, requiring precise mediastinal staging information, the role of TBNA in mediastinal staging will have to be reevaluated in the context of PET and CT information in prospective clinical trials. Only this approach will allow us to perform relevant cost-benefit analyses for the TBNA technique. The positive proof of N3 involvement by TBNA cytology or histology, however, will remain of decisive value.

1.
Van Tinteren H, Hoekstra OS, Smit EF, van den Bergh JH, Schreurs AJ, Stallaert RA, van Velthoven PC, Comans EF, Diepenhorst FW, Verboom P, van Mourik JC, Postmus PE, Boers M, Teule GJ: Effectiveness of positron emission tomography in the preoperative assessment of patients with suspected non-small-cell lung cancer: The PLUS multicentre randomised trial. Lancet 2002;359:1388–1392.
2.
Lardinois D, Weder W, Hany TF, Kamel EM, Korom S, Seifert B, von Schulthess GK, Steinert HC: Staging of non-small-cell lung cancer with integrated positron-emission tomography and computed tomography. N Engl J Med 2003;348:2500–2507.
3.
Pretreatment evaluation of non-small-cell lung cancer. The American Thoracic Society and The European Respiratory Society. Am J Respir Crit Care Med 1997;156:320–332.
4.
Harkin TJ, Wang KP: Bronchoscopic needle aspiration of mediastinal and hilar lymph nodes. J Bronchol 1997;4:238–249.
5.
Hermens FHW, Van Engelenburg TCA, Visser FJ, Thunnissen FBJM, Termeer R, Janssen JP: Diagnostic yield of transbronchial histology needle aspiration in patients with mediastinal lymph node enlargement. Respiration 2003;70:631–635.
© 2004 S. Karger AG, Basel
2004
Copyright / Drug Dosage / Disclaimer
Copyright: All rights reserved. No part of this publication may be translated into other languages, reproduced or utilized in any form or by any means, electronic or mechanical, including photocopying, recording, microcopying, or by any information storage and retrieval system, without permission in writing from the publisher.
Drug Dosage: The authors and the publisher have exerted every effort to ensure that drug selection and dosage set forth in this text are in accord with current recommendations and practice at the time of publication. However, in view of ongoing research, changes in government regulations, and the constant flow of information relating to drug therapy and drug reactions, the reader is urged to check the package insert for each drug for any changes in indications and dosage and for added warnings and precautions. This is particularly important when the recommended agent is a new and/or infrequently employed drug.
Disclaimer: The statements, opinions and data contained in this publication are solely those of the individual authors and contributors and not of the publishers and the editor(s). The appearance of advertisements or/and product references in the publication is not a warranty, endorsement, or approval of the products or services advertised or of their effectiveness, quality or safety. The publisher and the editor(s) disclaim responsibility for any injury to persons or property resulting from any ideas, methods, instructions or products referred to in the content or advertisements.