[61] Ezrin Significance in a Large Series of Ewing's Sarcoma Family of Tumors. Support: EuroBoNet (European Network of Excellence). Contract No. 018814.

Antonio LLombart-Bosch, Isidro Machado, Silvia Calabuig-Farinass, Jose Antonio Lopez-Guerrero, Marco Alberghini, Katia Scotlandi, Piero Picci. Valencia University, Spain; IVO, Valencia, Spain; Institute Ortopedic Rizzoli, Bologna, Italy

Background: Ezrin (a cytoskeletal protein) has been implicated as a conduit for signals between metastasis-associated cell-surface molecules and signal tranduction components. The aim of the present study is to described the implication of ezrin in a large series of genetically-confirmed ESFT and study the clinicopathological significance.
Design: A total of 324 ESFT genetically-confirmed were included in the study. The clinical data were reviewed and stored in a specific database. Out of the 324 tumors analyzed, 272 (84%) corresponded to primary localized tumors, 22 (7%) to disseminated primary tumors, 9 (3%) to recurrences, and 21 (6%) to metastases. For statistical considerations, disseminated primary tumors, recurrences, and metastases were grouped into the same category (disseminated disease). For the prognostic evaluation, we analyzed a cohort of 217 patients with localized disease. IHQ and FISH analysis were performed in TMAs (24). TMA sections were immunostained with ezrin antibody (clone 3C12, dilution 1:250).
Results: ESFT revealed ezrin expression in 61% of the tumors, ezrin was more frequently expressed in PNET (60%) compared with atypical (54%) and conventional (39%) ES (p=0.026). Ezrin was more frequently expressed in recurrences (100%), metastasis (78%) and disseminated primary tumors (61%), compared with the primary tumor (40%) (p<0.0001). Comparing ezrin expression between localized (40%) and disseminated (71%) cases, we observed a significant direct association between ezrin expression and disseminated cases (p<0.0001). In ESFT with strong ezrin expression, apoptotic cells did not express ezrin compared with non-apoptotic cells. In the multivariate analysis, ezrin immunoexpression (positive cases) represents an independent good prognostic factor for progression free survival/PFS (p=0.007) and disease specific survival/DSS (p=0.003).
Conclusions: Ezrin antibody is frequently expressed in ESFT, and does not offer any diagnostic clues for the differential diagnosis with other small round cell tumors of bone (osteosarcoma, chondrosarcoma, etc). Ezrin expression in disseminated cases is more frequently observed than in localized tumors; however, ezrin IHC expression represent an independent good prognostic factor for PFS and DSS.
Category: Bone & Soft Tissue

Tuesday, March 1, 2011 9:30 AM

Poster Session III # 10, Tuesday Morning

 

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