[1932] Automated Brightfield Dual In Situ Hybridization (BDISH) Technique Is Applicable for ASCO/CAP Guideline for HER2 Testing (ISH,IHC) in Breast Cancers: A Comparative Study

T Itoh, H Itoh, A Serizawa, N Kato, S Umemura, RY Osamura. Tokai Uvniersity School of Medicine, Isehara, Kanagaswa, Japan

Background: In addition to advanced breast cancers(BCs), early BCs have been treated with Trastuzumab and the incidence of HER2 testing has been increased. Heterogeneity of HER2 expression has been recommended to be included in the HER2 report as it is directly related to the therapeutic response(Arch Pathol Lab Med 2009;133:611-612). Our current study is aimed at to elucidate the feasibility of BDISH in interpreting HER2 expression according to ASCO/CAP guideline.
Design: Total 22 cases invasive ductal carcinoma of the breast were subjected to the following HER2 analysis, automated BDISH(Ventana Medical Systems Inc.), HER2/CEP17 Silver ISH(SISH),FISH(Vysis,Abbott). IHC included HercepTest(DAKO), CB11 and 4B5(Ventana Medical Systems Inc.).
Results: By FISH, cases #1-9 showed amplification by ASCO/CAP guideline. #10 and 11 were equivocal being 1,90 and 1.87 respectively. #12-22 were HER2 negative. By SISH, #1-8 and #19(1.18 by FISH)revealed amplification. #11 was equivocal. #10 and other cases were negative. By BDISH, #1-10 showed amplification. #11 and #17(1.30 by FISH) were equivocal. The remaining cases were negative.

For HER2 IHC, #1-9 were 3+ by 4B5 antibody. Case #2 was 2+ by HercepTest and CB11. #10-13,15-17,19-21 were 2+ by HercepTest. #11,13,17,19,21 were 2+ by CB11. The remaining cases were either 0 or 1+. Thus, 4B5 showed better concordance with ISH.
Conclusions: The combination of BDISH and IHC by 4B5 is expected to serve as good as, or slightly better than, the combination of FISH and HercepTest. Particularly, BDISH is more suitable for the interpretation of heterogeneity of HER2 gene amplification by using light microscope.
Category: Techniques

Monday, March 22, 2010 1:00 PM

Poster Session II # 257, Monday Afternoon

 

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