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F. Thivolet-Béjui
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P2.04 - Poster Session with Presenters Present (ID 466)
- Event: WCLC 2016
- Type: Poster Presenters Present
- Track: Mesothelioma/Thymic Malignancies/Esophageal Cancer/Other Thoracic Malignancies
- Presentations: 1
- Moderators:
- Coordinates: 12/06/2016, 14:30 - 15:45, Hall B (Poster Area)
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P2.04-005 - WHO Classification and IASLC/ITMIG Staging Proposal in Thymic Tumors: Real-Life Assessment (ID 4273)
14:30 - 14:30 | Author(s): F. Thivolet-Béjui
- Abstract
Background:
Thymic epithelial tumors (TETs) are rare intrathoracic malignancies which are categorized histologically according to the World Health Organization (WHO) classification, recently updated in 2015 based on a consensus statement of ITMIG (Marx et al. J Thorac Oncol 2014;9:596), and for which the standard Masaoka-Koga staging system is intended to be replaced by a TNM staging system based on an IASLC/ITMIG proposal (Detterbeck et al. J Thorac Oncol 2014;9:S65). Our objectives were 1/ to analyze the feasibility of assessing ITMIG consensus major and minor morphological and immunohistochemical (IHC) criteria in a routine practice setting, and their diagnostic performance for TETs histologic subtyping, and 2/ to assess the feasibility and the relevance of the proposed IASLC/ITMIG TNM staging system with regards to the Masaoka-Koga staging system.
Methods:
This is a monocenter study conducted at the Lyon University Hospital, one of the largest centers for TETs in France. Overall, 188 consecutive TETs diagnosed in 181 patients since 2000 at our center were analyzed. Systematic pathological review of cases was conducted.
Results:
There were 168 (89%) thymomas, including 9 (5%) type A, 67 (36%) type AB, 19 (10%) type B1, 46 (24%) type B2, and 27 (14%) type B3, and 20 (11%) thymic carcinomas (TC). After exclusion of necrotic and non-suitable specimens, 178 tumors were reviewed for ITMIG consensus major and minor criteria. Major criteria were identified in 100% of type A, AB, B1 and B2 thymomas. With regard to minor criteria, rosettes, glandular formations, subcapsular cysts, and pericytomatous vascular pattern were typical for type A thymomas, and were not identified in other subtypes. Perivascular spaces were more frequent in type B thymomas (48% of cases) than AB thymomas (7% of cases). For type B3 thymomas, pink appearance at low magnification, lobular growth, lack of intercellular bridges and lack of expression of CD117 were presents in all cases. Masaoka-Koga staging was assessable for 156 patients: there were 42 (27%) stage I, 55 (35%) stage IIa, 28 (18%) stage IIb, 22 (14%) stage III, 4 (3%) stage IVa, and 5 (3%) stage IVb tumors. After restaging according to the IASLC/ITMIG TNM classification, there were 127 (81%) stage I, 3 (2%) stage II, 17 (11%) stage IIIa, no stage IIIb, 5 (3%) stage IVa, and 4 (2%) stage IVb.
Conclusion:
Our results indicate the feasibility of the ITMIG consensus statement on the WHO histological classification, and highlights the switch in staging when applying the IASLC/ITMIG TNM classification proposal.
