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Staging of Lung Cancer FREE TO VIEW

Robert Milroy, MD
Author and Funding Information

Glasgow, Scotland

Correspondence to: Robert Milroy, MD, Department of Respiratory Medicine, Stobhill Hospital, 133 Balornock Rd, Glasgow, G21 3UW, Scotland, UK; e-mail: robert.milroy@northglasgow.scot.nhs.uk


Chest. 2008;133(3):593-595. doi:10.1378/chest.07-2638
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Published online

The accurate staging of lung cancer is essential in planning treatment, and it is of crucial prognostic significance. Indeed, in the assessment of lung cancer patients, staging along with obtaining a histologic diagnosis are the two essential factors in treatment planning. In addition, accurate assessment of and documentation of performance status and clear recording of comorbidity are vital.

Lung cancer staging hinges on both noninvasive (CT and CT positron emission tomography),1minimally invasive (transbronchial needle aspiration with or without endobronchial ultrasound guidance,2endoscopic ultrasound fine-needle aspiration3and neck ultrasound fine-needle aspiration),4as well as sometimes invasive staging (mediastinoscopy, mediastinotomy, and nodal dissection at thoracotomy).5The current TNM classification for lung cancer is based on the most recent revision of the international staging system published by Mountain6 in 1997. This is based on a relatively small database of 5,319 cases of non-small cell lung cancer (NSCLC). As in previous lung cancer staging publications, the tumor stage (T1–T4) was based on tumor size and proximity to and involvement of vital intrathoracic structures as well as including non–size-based descriptors. Specifically in the case of T2 disease, stage was not only based on size but also based on visceral pleura invasion, hilar atelectasis, and obstructive pneumonitis, and a tumor could be staged as T2, even if < 3 cm, if any of these non–size-based descriptors were present. Nodal status was divided into N0 (no local node involvement), N1 (ipselateral hilar node), N2 (ipselateral mediastinal node), or N3 (contralateral mediastinal node or supraclavicular node) involvement. Using the T and N descriptors, in the absence of metastatic disease, lung cancer has been staged as 1A, 1B, 2A, 2B, 3A, and 3B. This staging system has proved extremely useful in categorizing patients both in terms of treatment and recruitment to studies and in terms of prognosis.

The International Association for the Study of Lung Cancer (IASLC) established a lung cancer staging project in 1998 to bring together the large databases available worldwide and to form recommendations for the seventh edition of the TNM staging system. Data were obtained from 46 sources in 19 countries, and a total of almost 68,000 cases of NSCLC treated with all modalities of care between 1990 and 2000 were entered into the database. Following analysis and intensive validation of this large database, recommendations for changes to the T, N, and M descriptors were incorporated into TNM subsets, and these will be incorporated in the seventh edition of the TNM classification of malignant tumors due to be published in 2009.

The IASLC lung cancer staging project committee has recognized the crucial importance of tumor size and has recommended that T1 tumors be subclassified into T1a (≤ 2 cm) and T1b (> 2 cm). In addition, the committee recommend that T2 tumors be classified into T2a (> 3 cm and < 5 cm), T2b (> 5 cm and < 7 cm), and T2c (> 7 cm), with T2c being reassigned to T3.7 However, the IASLC staging project7 did not incorporate recommendations regards non–size-based T2 descriptors because “these could not be evaluated either because of the small number of patients, the inconsistent clinical and pathologic results, or lack of validation.”

The details of this major project have been summarized recently in a series of articles in the Journal of Thoracic Oncology.811 The authors have indicated, however, that one of the main limitations of this staging project is that most of the contributing databases were not specifically designed to study the TNM classification.

The study by Ou et al12 published in this edition of CHEST (see page 662) is an interesting and important population-based analysis of > 10,000 patients with stage 1B NSCLC addressing the prognostic significance of non–size-based T2 descriptors, and adds valuable information regarding T2 staging. The study reports a large retrospective series evaluating the prognostic features of surgically resected stage 1B NSCLC in terms of T status. The authors adjusted for many known prognostic factors such as age, gender, histology, tumor location, socioeconomic status, and type of surgical treatment in their analysis of prognostic factors. An important aspect of this study is the fact that the patients analyzed were restricted to stage IB (T2N0) patients, thereby avoiding any confounding factors related to hilar and mediastinal nodal involvement.

The purpose of the study was to evaluate the prognostic significance of non–size-based descriptors for T2, namely visceral pleura invasion, hilar atelectasis or obstructive pneumonitis (T2p), and main bronchus involvement > 2 cm from the carina (T2c). The authors have confirmed that size (ie, T2 due to tumor > 3 cm, T2s) is an important prognostic indicator. This is consistent with the recommendations of the IASLC Staging Committee.

However, the authors have also clearly demonstrated that if the tumor is graded as T2 solely on the basis of non–size-based descriptors (T2p or T2c), then these patients who have tumors ≤ 3 cm have a better prognosis than T2s patients (ie, patients with tumors > 3 cm). This was the case in 2,224 of 10,545 patients evaluated (21.1%) who had stage IB tumors ≤ 3 cm because they were staged as T2 solely by non–size-based T2 descriptor criteria. Despite these patients being staged as IB, their 5-year and median overall survival rates were similar to that of a group of almost 10,000 stage IA patients used as comparator. Thus, T2p tumors that are T2 only for this reason (ie, T2p and < 3 cm) demonstrate an independent favorable prognosis when compared to stage IB patients who are staged IB because of tumor size > 3 cm. In addition, the authors have shown that the presence of T2p in tumors > 3 cm is an independent poor prognostic factor for survival.

It is, of course, well known that tumor size is a classic determinant of survival in NSCLC, but the authors have clearly shown that the prognostic significance of non–size-based T2 descriptors (specifically visceral pleura invasion/hilar atelectasis/obstructive pneumonitis) are adverse prognostic factors in tumors > 3 cm, whereas in tumors < 3 cm their presence does not indicate an adverse prognosis and in fact patients with T2 only due to non–size-based descriptors have a prognosis equivalent to stage 1A patients.

This is an important piece of work that adds significantly to discussions in relation to the next revision of the TNM staging system for NSCLC that is scheduled to be released in 2009. In particular, future considerations to the changes in the T2 descriptor in the lung cancer staging system for NSCLC suggests that non–sized-based criteria should be linked to size criteria rather than remaining as independent criteria.

Dr. Milroy is Consultant Physician, Department of Respiratory Medicine, Stobhill Hospital.

The author has no conflict of interest to disclose.

References

Devaraj, A, Cook, GJ, Hansell, DM (2007) PET/CT in non small cell lung cancer staging-promises and problems.Clin Radiol62,97-108
 
Herth, FJ, Rabe, KF, Gasparini, S, et al Transbronchial and transoesophageal (ultrasound-guided) needle aspirations for the analysis of mediastinal lesions.Eur Respir J2006;28,1264-1275
 
Micames, MD, McCrory, DC, Pavey, DA, et al Endoscopic ultrasound-guided fine-needle aspiration for non-small cell lung cancer staging a systematic review and metaanalysis.Chest2007;131,539-548
 
Kumaran, M, Benamore, RE, Vaidhyanath, R, et al Ultrasound guided cytological aspiration of supraclavicular lymph nodes in patients with suspected lung cancer.Thorax2005;60,229-233
 
Graham, ANJ, Chan, KJM, Pastorino, U, et al Systematic nodal dissection in the intrathoracic staging of patients with non-small cell lung cancer.J Thorac Cardiovasc Surg1999;117,246-251
 
Mountain, CF Revisions in the international staging system for staging lung cancer.Chest1997;111,1710-1717
 
Rami-Porta, R, Ball, D, Crowley, JJ, et al The IASLC Lung Cancer Staging Project: proposals for revision of the T descriptors in the forthcoming (seventh) edition of the TNM classification of malignant tumours.J Thorac Oncol2007;2,593-602
 
Goldstraw, P, Crowley, J, Chansky, K, et al The IASLC Lung Cancer Staging Project: proposals for the revision of the TNM stage groupings in the forthcoming (seventh) edition of the TNM classification of malignant tumours.J Thorac Oncol2007;2,603-612
 
Rusch, V, Crowley, JJ, Goldstraw, P, et al The IASLC Lung Cancer Staging Project: proposals for revision of the N descriptors in the forthcoming (seventh) edition of the TNM classification of malignant tumours.J Thorac Oncol2007;2,706-714
 
Postmus, PE, Brambilla, E, Chansky, K, et al The IASLC Lung Cancer Staging Project: proposals for revision of the M descriptors in the forthcoming (seventh) edition of the TNM classification of malignant tumours.J Thorac Oncol2007;2,686-693
 
Groome, PA, Bolejack, V, Crowley, JJ, et al The IASLC Lung Cancer Staging Project: validation of the proposals for revision of the T, N, and M descriptors and consequent stage groupings in the forthcoming (seventh) edition of the TNM classification of malignant tumours.J Thorac Oncol2007;2,694-705
 
Ou, SHI, Zell, JA, Ziogas, A, et al Prognostic significance of the non-size based AJCC T2 descriptors: visceral pleura invasion, hilar atelectasis or obstructive pneumonitis in stage 1B non-small-cell lung cancer is dependent on tumour size.Chest2008;133,662-669
 

Figures

Tables

References

Devaraj, A, Cook, GJ, Hansell, DM (2007) PET/CT in non small cell lung cancer staging-promises and problems.Clin Radiol62,97-108
 
Herth, FJ, Rabe, KF, Gasparini, S, et al Transbronchial and transoesophageal (ultrasound-guided) needle aspirations for the analysis of mediastinal lesions.Eur Respir J2006;28,1264-1275
 
Micames, MD, McCrory, DC, Pavey, DA, et al Endoscopic ultrasound-guided fine-needle aspiration for non-small cell lung cancer staging a systematic review and metaanalysis.Chest2007;131,539-548
 
Kumaran, M, Benamore, RE, Vaidhyanath, R, et al Ultrasound guided cytological aspiration of supraclavicular lymph nodes in patients with suspected lung cancer.Thorax2005;60,229-233
 
Graham, ANJ, Chan, KJM, Pastorino, U, et al Systematic nodal dissection in the intrathoracic staging of patients with non-small cell lung cancer.J Thorac Cardiovasc Surg1999;117,246-251
 
Mountain, CF Revisions in the international staging system for staging lung cancer.Chest1997;111,1710-1717
 
Rami-Porta, R, Ball, D, Crowley, JJ, et al The IASLC Lung Cancer Staging Project: proposals for revision of the T descriptors in the forthcoming (seventh) edition of the TNM classification of malignant tumours.J Thorac Oncol2007;2,593-602
 
Goldstraw, P, Crowley, J, Chansky, K, et al The IASLC Lung Cancer Staging Project: proposals for the revision of the TNM stage groupings in the forthcoming (seventh) edition of the TNM classification of malignant tumours.J Thorac Oncol2007;2,603-612
 
Rusch, V, Crowley, JJ, Goldstraw, P, et al The IASLC Lung Cancer Staging Project: proposals for revision of the N descriptors in the forthcoming (seventh) edition of the TNM classification of malignant tumours.J Thorac Oncol2007;2,706-714
 
Postmus, PE, Brambilla, E, Chansky, K, et al The IASLC Lung Cancer Staging Project: proposals for revision of the M descriptors in the forthcoming (seventh) edition of the TNM classification of malignant tumours.J Thorac Oncol2007;2,686-693
 
Groome, PA, Bolejack, V, Crowley, JJ, et al The IASLC Lung Cancer Staging Project: validation of the proposals for revision of the T, N, and M descriptors and consequent stage groupings in the forthcoming (seventh) edition of the TNM classification of malignant tumours.J Thorac Oncol2007;2,694-705
 
Ou, SHI, Zell, JA, Ziogas, A, et al Prognostic significance of the non-size based AJCC T2 descriptors: visceral pleura invasion, hilar atelectasis or obstructive pneumonitis in stage 1B non-small-cell lung cancer is dependent on tumour size.Chest2008;133,662-669
 
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