[92] 2007 ASCO/CAP Guidelines: Impact on HER 2 IHC Results.

Gabriela Acosta Haab, Isabel Frahm, Sandra Sarancone, Valeria Caceres. Hospital Marie Curie, Buenos Aires, Argentina; Sanatorio Mater Dei, Buenos Aires, Argentina; Laboratorio Quantum, Rosario, Santa Fe, Argentina; Productos Roche, Tigre, Buenos Aires, Argentina

Background: Precise, validated and reproducible HER 2 assessment is critical for breast cancer patient's management. A joint ASCO/CAP Task Force updated guidelines and recommendations for HER2 testing in 2007, an important step forward in attempting to improve HER2 accuracy. Guidelines counsel how results should be interpreted and reported: HER2 3 + immunohistochemical (IHC) scoring has changed the threshold from 10 to 30% membrane staining. The aim of study was to determine the impact of the 2007 ASCO/CAP guidelines on HER 2 IHC results.
Design: HER2 over-expression was prospectively analyzed by IHC test in 4318 invasive breast carcinomas cases from March 2009 to September 2010. HER-2 was performed using policlonal antibody anti Her 2 (DAKO), microwave antigenic recovery, detection system EnVision (Dako) and developed with diaminobenzidine. Results were recorded simultaneously with both scoring criterion.
Results: Based on the updated guidelines, we found:

2007 ASCO/CAP HER 2 Testing Score in 4318 cases
ScoreCases%
Negative358182.93
Equivocal1313.03
Positive60614.03


10 cases/606 (1.65 %) were down-scored from 3+ to 2+ (equivocal), 2/10 were core biopsies then reanalyzed in tissues samples and scored again as 3 +, and 4 /10 were also dubious by FISH (1.8-2.2).
Conclusions: Our study demonstrated that 2007 ASCO/CAP Guidelines threshold staining change, in fact, has no effect upon reducing the number of 3+ cases (1.65%). Core biopsies should be analyzed with caution. The ASCO/CAP Task Force recognizes that there is an equivocal gray zone or borderline category that is occasionally encountered when interpreting the results (4 cases).
Category: Breast

Wednesday, March 2, 2011 9:30 AM

Poster Session V # 4, Wednesday Morning

 

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