“Validation” of the Proposed IASLC/ITMIG Staging Revisions of Thymic Carcinomas Using Data from 287 Patients Yang Zhao; Heng Zhao Division of Thoracic Surgery Shanghai Chest Hospital AATS ， Seattle, April 27th 2015

Disclosure No conflicts related to this presentation; Not a true validation study, only evaluation process; Some statistic flaw amended by professional statistic personnel with resultant new results and conclusions;

BACKGROUND Thymic carcinoma ： A relatively rare neoplasm; With distinct pathologic and clinical characteristics (overt cytological atypia;lack of organotypical features); First reported by Shimosato (Am J Surg Pathol 1977;1:109–21); Nomenclature: 1982, Snover, Levine, Rosai (Am J Surg Pathol 1982;6:451-70); 2004 WHO classification: 13 histological subtypes;

No official stage classification for thymic malignancies has been defined by the UICC and AJCC; From 2010, ITMIG recommended Masaoka-Koga stage classification system; (James Huang. JCO 2010;5: ) 1981, Masaoka, based on 93 patients; 1994, Koga, based on 79 patients; Has many ambiguities that have not been clearly defined

The Masaoka system is limited to thymomas and does not seem to properly predict the outcome of TC. Masaoka stage did not have any statistical impact on survival. (Pier Luigi Filosso.Lung cacer 2014;83; ) (40cases) (Yang Zhao. Ann Thorac Surg 2013;96:1019–24) (105 cases) (Yusuke Okuma. Lung Cancer 2014;84: ) (68 cases) (Usman Ahmad. JTCVS 2015;149:95-101)(ITMIG&ESTS,1042cases) (Motoki Yano. JTO 2008;3: ) (30 cases) But not in the SEER cohort (Benny Weksler ATS2013;95: )

In 2014, the IASLC/ITMIG launched a worldwide TNM staging proposal to inform the next edition of thymic tumors. Recommended that this proposed staging system is also applicable to thymic carcinomas.

The rationale of this study is that a solidly staging system should been subjected to an intense evaluation process before officially published and widely accepted.

METHODS A retrospective review, single institution, consecutive patients, Pathologically confirmed thymic carcinoma; Carcinoid tumors were excluded ； Treated from February 2003 to April 2014; The last general follow-up of survivors was done at the end of October 2014;

287 patients was enrolled and 263 (91.6%) of them had complete follow-up data. Follow-up data was completed with a median of 32.0 months (range, months).

Patients Characteristics

Survival OS: 5-years = 63.0%; 10-years = 46.5%; the median survival time = ± 19.1 months; DFS: 5-years = 43.4%; 10-years = 23.5%; the median recurrence time = 40.0 ± 7.4 months; At the conclusion of the study: 127 patients (48.3%) were alive with no evidence of disease progression; 57 were alive with the disease (21.7%); 72 died with the disease (27.4%); Seven patients (2.7%) died from disease-unrelated causes postoperatively.

A migration of stage distribution between these two system

OS of our 263 TC patients IASLC & ITMIG

ITMIG & IASLC OS of our 263 TC patients

Masaoka-Koga systemProposed TNM system

Overall Survival Masaoka-Koga systemProposed TNM system

Disease-free Survival Masaoka-Koga systemProposed TNM system

Limitations: Inherent biases associated with the retrospective study design; Experience of a single center ； Strengths: An international classification system must be reproducible in the diverse setting in which it is applied. In our 287 patients, 9.4% (27/287) managed nonsurgically, thus making this findings more generalizable. The prognostic ability of the staging system was verified by a multivariate analysis that considers other prognostic factors, i.e., sex, age, completeness of resection, yielding statistically valid analyses.

Summary The proposed TNM staging system shows priority on predicting clinical course compared with the conventional Masaoka-Koga system in thymic carcinoma patients for its capability of predicting both OS and DFS efficiently, compared failure of Masaoka-Koga system on OS predicting. We advocate this new system to be an official one on our clinical practice.

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