[1839] Determination of HER2 Status Variability by Immunohistochemistry in Chile.

Luis Contreras, Maria Garmendia, Jorge Levican, Antonio Piottante. Clinica Las Condes, Santiago, Chile

Background: The cancer treatment based on molecular targets, is in active research and development. The HER2 is one of the most studied drug targets The determination of HER2 gene status in breast cancer is a prognostic and predictive marker. This status must be determined with an exact technique for an adequate therapeutic decision.
Design: During 2008 and 2009 we analyzed 221 biopsies from 221 women with invasive breast cancer sent by 41 chilean pathology laboratories to determine HER2 status by Fluorescent In Situ Hybridization (FISH). 201 biopsies allow analysis (90.1%). In our Lab the HER2 status was determined by IHC and FISH in a standardized way in accordance with the American Society of Clinical Oncology and the College of American Pathologists (ASCO/CAP) recommendations. These results were compared with the original HER-2 IHC reports from different laboratories.
Results: The variability of the assessment of HER2 status in the 41 national laboratories is similar to that described in international literature, reaches 19.7% when compared with standard IHC technique and reach 26.9% when compared with FISH. The rate of false positives in IHC is 15.7% and 25.6% when compared to FISH, the false negative rate reaches 28.7% for both IHC and FISH.
Conclusions: This study confirms the need for Chilean laboratories carrying out the determination of HER2 status to implement validated IHC technique with stringent quality controls both internal and external, employing standardized technical and interpretative procedures according to international recommendations for a proper therapeutic decision.
Category: Quality Assurance

Monday, February 28, 2011 1:00 PM

Poster Session II # 210, Monday Afternoon


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