Comprehensive immunohistochemical analysis of Her-2/neu oncoprotein overexpression in breast cancer: HercepTest™ (Dako) for manual testing and Her-2/neuTest 4B5 (Ventana) for Ventana BenchMark automatic staining system with correlation to results of fluorescence in situ hybridization (FISH)

PURPOSE: The objective of our study was to compare the methods used in the literature to analyze HER-2/neu status on archival breast cancer tissue. Therefore, a series of antibodies was evaluated to assess their immunohistochemical (IHC) sensitivity in correlation to gene amplification determined by fluorescence in situ hybridization (FISH). MATERIALS AND METHODS: HER-2/neu overexpression was studied on paraffin sections of 85 invasive breast cancers using a panel of five monoclonal (9G6, 3B5, CB11, TAB250, GSF-HER2) and two polyclonal antibodies (A8010, A0485) in addition to the HercepTest (DAKO, Glostrup, Denmark). HER-2/neu gene amplification was determined by FISH using a dual-color probe (PathVysion; Vysis, Stuttgart-Fasanenhof, Germany). RESULTS: HER-2/neu overexpression was demonstrated in 26% (9G6, TAB250, GSF-HER2), 27% (3B5, CB11), 33% (A8010) and 42% (A0485, HercepTest) of the tumors. FISH on paraffin sections identified gene amplification in 28% of the tumors. Strongly positive IHC results (3+) were always associated with gene amplification. Among the 16 tumors presented with weakly positive IHC results (2+) using the HercepTest, 12 (75%) lacked gene amplification. CONCLUSION: The comparison of IHC and FISH demonstrated an excellent correlation of high-level HER-2/neu overexpression (3+) with gene amplification; ie, FISH does not provide further information in these tumors. However, weakly positive IHC results (2+) obtained with the HercepTest share only a minor association with gene amplification.

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Assessment of Methods for Tissue-Based Detection of the HER-2/neu Alteration in Human Breast Cancer: A Direct Comparison of Fluorescence In Situ Hybridization and Immunohistochemistry

Journal of Clinical Oncology ◽

10.1200/jco.2000.18.21.3651 ◽

2000 ◽

Vol 18 (21) ◽

pp. 3651-3664 ◽

Cited By ~ 450

Author(s):

Giovanni Pauletti ◽

Suganda Dandekar ◽

HongMei Rong ◽

Lilllian Ramos ◽

HongJun Peng ◽

...

Keyword(s):

Breast Cancer ◽

In Situ Hybridization ◽

Fluorescence In Situ Hybridization ◽

Gene Amplification ◽

Survival Probability ◽

Human Breast Cancer ◽

Patient Survival ◽

Human Breast ◽

Her 2

PURPOSE: To compare the efficacy of fluorescence in situ hybridization (FISH) and immunohistochemistry (IHC) in detecting the HER-2/neu alteration in human breast cancer. PATIENTS AND METHODS: Unselected stage I, II, and III breast cancer patients (N = 900) were tested for HER-2/neu gene amplification by FISH in paraffin-embedded, formalin-fixed archival material. Of these samples, 856 were tested for HER-2/neu overexpression by non–antigen-retrieval IHC with the polyclonal antibody R60, the sensitivity and specificity of which was preliminarily compared with the United States Food and Drug Administration–approved HercepTest (Dako Corp, Carpinteria, CA). Patient survival was analyzed in relation to the presence of the HER-2/neu alteration as determined by these two methodologies. RESULTS: A total of 189 (21%) of 900 patients were positive by FISH and 147 (17.2%) of 856 were positive by IHC. This discrepancy is consistent with expected loss of IHC sensitivity associated with tissue fixation/embedding. The HercepTest did not improve sensitivity and introduced false positives. Comparison of R60-based IHC with FISH demonstrates that patient survival is associated progressively to gene amplification level as determined by FISH, whereas for IHC an association is found only in the highest (3+) immunostaining group. Among FISH-negative tumors, 45 (6.6%) of 678 were IHC-positive, with a survival probability similar to that of FISH-negative/IHC-negative cases; FISH-positive/IHC-negative patients have a survival probability similar to that of FISH-positive/IHC-positive cases. CONCLUSION: IHC does not consistently discriminate patients likely to have a poor prognosis, whereas FISH provides superior prognostic information in segregating high-risk from lower-risk beast cancers. HER-2/neu protein overexpression in the absence of gene amplification occurs infrequently in breast cancer, in which case, patient outcome is similar to that of patients without the alteration.

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