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Ann Thorac Surg 2003;75:1718-1719
© 2003 The Society of Thoracic Surgeons

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Original article: general thoracic

Invited commentary

^a Department of Surgery, Memorial Sloan-Kettering Cancer Center, 1275 York Avenue, Rm C-867New York, NY 10021, USA

e-mail: ruschv{at}mskcc.org

Malignant pleural mesothelioma (MPM), previously thought to be uniformly fatal within two years of diagnosis, is now known to be resectable in many patients with a significant chance of 5-year survival. The patients who are most likely to benefit from surgery and adjuvant therapy include those with early stage, node negative, purely epithelial tumors. However, the accurate preresection staging of MPM patients remains challenging. Imaging studies, especially CT scanning, are the best noninvasive ways of staging MPM, but fail to identify correctly either locally advanced primary tumor (T3 or T4) or lymph node metastases (N1 or N2 disease) in 10 to 20 percent of patients. Schouwink and colleagues find that cervical mediastinoscopy is considerably more accurate than CT in detecting N2 disease, and recommend that it be used routinely for preresection staging. Is this recommendation on target?

The inaccuracies of CT scanning in detecting N2 disease are well known. Difficulties in distinguishing between mediastinal pleural disease and mediastinal lymph nodes, a lack of correlation between nodal size and the presence of malignancy, and metastatic lymph nodes in unusual locations (eg the peridiaphragmatic or internal mammary regions) all contribute to the inaccuracy of CT. Therefore, it is not surprising that mediastinoscopy identifies N2 disease more accurately. Importantly, this study corroborates and extends findings in previous large series. However, the authors also do not fully emphasize the shortcomings of mediastinoscopy. Nine of 43 (21 percent) of patients were found to have N2 disease that was not diagnosed by mediastinoscopy, either because the lymph nodes were missed or were inaccessible.

Although lymph node metastases have an adverse prognostic impact, it is still unclear whether all MPM patients with N2 disease should be denied resection because several other factors play important roles in determining outcome. These include the number of involved lymph nodes, the primary tumor T status, the histological subtype, and as yet unidentified biological factors. It is likely, for example, that a T2 epithelial tumor with two positive lymph nodes has a different prognosis than a T3 tumor of mixed histology with 10 positive lymph nodes. Until additional data become available that allow patients to be stratified more accurately based on the relative impact of multiple prognostic factors in MPM, we need to be cautious about making arbitrary treatment decisions related to a single prognostic factor. A decision not to offer a patient resection and adjuvant therapy implies that the therapeutic approach offers no benefit or that a better treatment is available, or both. The median postoperative survival of patients with stage III MPM is approximately one year, so the decision to do a procedure such as an extrapleural pneumonectomy can legitimately be questioned. Unfortunately, our lack of precise knowledge of prognostic factors in this disease still makes it difficult to predict outcome for an individual patient. In essence, additional data are needed to construct a treatment nomogram for MPM.

Schouwink et al provide important information about the contribution of mediastinoscopy to the initial staging of MPM. Although caution should be exercised about making treatment decisions solely on the basis of mediastinoscopy, it is an useful staging tool. Current trials testing the use of induction chemotherapy, surgical resection and adjuvant hemithoracic radiation target patients who have locally advanced MPM (T3 or T4 or N2). In this setting, mediastinoscopy can be key in selecting patients for protocol therapy.

This Article Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Email this article to a friend Similar articles in this journal Alert me to new issues of the journal Add to Personal Folders Download to citation manager Author home page(s): Valerie W. Rusch Permission Requests Citing Articles Citing Articles via Google Scholar Google Scholar Articles by Rusch, V. W. Search for Related Content PubMed Articles by Rusch, V. W.