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Ann Thorac Surg 2006;82:1170-1171
© 2006 The Society of Thoracic Surgeons

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Correspondence

Reply

Istituto Nazionale Tumori, Via G Venezian 1, Milan, 20133 Italy

(Email: amedeovittorio.bedini{at}istitutotumori.mi.it).

To the Editor:

Utsumi and Okumura [1] focus their letter on three points: (1) they request the data on which our proposal [2] is based, according to the classification of pleural-pericardial implants, (2) they do not approve merging Masaokas's stages IVa and IVb into one set [3], and (3) they recommend dividing Masaoka's stage III into two groups. Utsumi and Okumura [1] conclude that our classification requires more discussion before it can be accepted.

The TNM scheme we propose, which we call the Istituto Nazionale Tumori (INT) system, is based on the proposal by Yamakawa and colleagues [3] who translated Masaoka's system into TNM categories. These are grouped to reproduce Masaoka's stages [3].

In regard to the first point, we modified the TNM descriptors by following resectability criteria [4]. This is clearly stated in our article. Thus there is no need to justify the distinction of one specific feature of disease according to the feasibility or unfeasibility of a standard surgical radical resection. Needless to say, achievement of complete resection is one of the most important prognostic factors in thymic tumors. Moreover, our decision to stage pleural-pericardial implants as T4, when encompassed by margins of standard Jaretzki's procedure [5], and as M1, if beyond its boundaries is analogous with TNM descriptors of lung carcinoma. In fact, the presence of multiple lesions within the lobe of a primary lung tumor is classified as T4 and as M1 if another lobe of the same lung is involved by other lesions. This choice reflects the need to identify the extent of disease amenable to the standard lobectomy in the presence of metastases.

In regard to the second point, Utsumi and Okumura [1] declare that we merge Masaoka's stages IVa and IVb into one set. This is simply not the case. In fact, we group selected IVa patients (those with limited and radically resectable pleural-pericardial implants, which we classified as T4) and selected IVb patients (those with intrathoracic nodal spread, which we classify as N1–2) in the intermediate stage of our system. The remaining Masaoka IVa–IVb cases are included in the advanced stage. Masaoka's system groups both first-level involvement of anterior mediastinal nodes and distant hematogenous metastases together in the most advanced stage (or IVb). This grouping presents no analogy with other TNM staging systems nor logical justifications from our point of view.

We fully agree with the third comment of Utsumi and Okumura [1]. In fact, we stated in the Comment section of our article that "...Some of the features included in INT intermediate stage...could justify a subdivision of this stage into two. However, for the purpose of this initial effort, we thought it prudent to follow strictly the parsimony criterion in order to avoid numerical inconsistency of the groups." The last sentences of our article were: "There is a plan to collect a larger multi-institutional series to perform further assessment of the INT system. We are hopeful that this proposal will be deemed worthy of independent evaluation by the scientific community."

In conclusion, we believe that our TNM proposal describes disease progression with improved accuracy over the TNM definitions suggested by Yamakawa and colleagues [3]. Our stages, which include patients with specific therapy options, show a significantly better prognostic separation than the stages of Masaoka's system. However, we admit that the grouping we propose can be modified by subdivision of the intermediate stage if an adequate number of cases can be evaluated.

	References

Top References

 

1. Utsumi T, Okumura M. A staging system for thymic epithelial tumorsmore discussion is required (letter). Ann Thorac Surg 2006;82:1170.[Free Full Text]
2. Bedini AV, Andreani SM, Tavecchio L, et al. Proposal of a novel system for the staging of thymic epithelial tumors Ann Thorac Surg 2005;80:1994-2001.[Abstract/Free Full Text]
3. Yamakawa Y, Masaoka A, Hashimoto T, et al. A tentative tumor-node-metastasis classification of thymoma Cancer 1991;68:1984-1987.[Medline]
4. Masaoka A, Monden Y, Nakahara K, et al. Follow-up study of thymomas with special reference to their clinical stages Cancer 1981;48:2385-2392.
5. Jaretzki III A, Wolf M. Maximal thymectomy for mhyastenia gravis J Thorac Cardiovasc Surg 1988;96:711-716.[Abstract]

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 Permission Requests Citing Articles Citing Articles via Google Scholar Google Scholar Articles by Bedini, A. V. Search for Related Content PubMed Articles by Bedini, A. V. Related Collections Related Article