Ann Thorac Surg 2009;88:378-379. doi:10.1016/j.athoracsur.2009.04.072
© 2009 The Society of Thoracic Surgeons
Original Articles: General Thoracic
Invited Commentary
Alan D. Sihoe, MB BChir, FRCSEd(CTh)
Department of Cardiothoracic Surgery, The University of Hong Kong, Queen Mary Hospital, Hong Kong SAR, China
(Email: adls1{at}lycos.com).
The 2009 revisions for the international TNM staging system for lung cancer are being anticipated with great expectations by many clinicians. One of the key areas for improving the 1997 edition is the redefining of T4 tumors, previously a heterogeneous mix of various clinical situations. Satellite nodules within the same lobe as the primary tumor and malignant pleural effusions are now due to be redefined as T3 and M1 lesions, respectively [1]. For T4 tumors defined by mediastinal invasion, the 2009 revisions are poised to acknowledge emerging evidence suggesting that outcomes of surgery may be reasonably good in carefully selected patients. The study by Yang and colleagues [2] in this issue is one example of such evidence. In one of the largest series to date, they report an overall 5-year survival rate of 22.7% in their cohort of 146 patients with T4 lung cancer defined by mediastinal invasion. In patients with R0 resection and N0 or N1 nodal status, that figure rises remarkably to more than 40%. Such results give emphatic credence to the decision to categorize T4N0M0 and T4N1M0 disease as stage IIIA in the 2009 revisions [3]. Presumably, future surgeons may be called on to contemplate technically challenging resections of such invasive T4 tumors with increasing frequency.
It is helpful that studies such as this have already begun to identify some key criteria for selecting patients for such surgery. One consideration is that all 4 patient deaths in this series occurred after a pneumonectomy, and the authors' advice to consider pneumonectomy only with great caution in these patients should be duly heeded. On the other hand, concern about avoiding pneumonectomy should not override the principle of achieving R0 resection where possible. Another consideration is that N2 nodal metastasis is associated with dismal survival in this group of patients and should contraindicate surgery. It must be emphasized that all 146 patients in this series were deemed not to have N2 nodal metastasis on preoperative staging, yet 95 (65%) were ultimately found to have such metastasis on final pathology. The authors suggest quite reasonably that the central T4 tumors may have confounded accurate mediastinal nodal assessment on computed tomographic scanning. If this is the case, it may also be doubtful whether positron emission tomographic scanning would be any better in this role. Therefore, mediastinoscopy should probably be considered mandatory in all patients with suspected T4 tumors being considered for lung resection.
Even with the best preoperative planning, mediastinal invasion is sometimes only discovered intraoperatively. In this series, T4 tumor status was only confirmed at the time of thoracotomy in almost a quarter of the patients. In such situations, the best course of action is unclear. Given the potentially reasonable survival with R0 resection, can it still be an acceptable option in the future to simply abort further resection? Should N2 mediastinal lymph nodes be immediately sampled for frozen section analysis and further resection based on the results? What is the role of preoperative neoadjuvant or postoperative adjuvant chemoradiotherapy and radiotherapy in such scenarios? These are just some of the questions that need to be addressed by future studies.
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References
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- Rami-Porta R, Ball D, Crowley J, 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 lung cancer J Thorac Oncol 2007;2:593-602.[Medline]
- Yang HX, Hou X, Lin P, Rong TH, Yang H, Fu JH. Survival and risk factors of surgically treated mediastinal invasion T4 non-small cell lung cancer Ann Thorac Surg 2009;88:372-379.[Abstract/Free Full Text]
- Goldstraw P, Crowley J, Chansky K, et al. The IASLC Lung Cancer Staging Project: proposals for revision of the TNM stage groupings in the forthcoming (seventh) edition of the TNM classification of malignant tumours J Thorac Oncol 2007;2:706-714.[Medline]
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