HER-2/neu analysis in breast cancer bone metastases
- J Zustin1,
- K Boddin1,
- M C Tsourlakis1,
- E Burandt1,
- M Mirlacher1,
- F Jaenicke2,
- J Izbicki3,
- W Ruether4,
- J M Rueger5,
- C Bokemeyer6,
- R Simon1,
- G Sauter1
- 1Institute of Pathology, University Medical Center Hamburg-Eppendorf, Germany
- 2Department of Gynecology, University Medical Center Hamburg-Eppendorf, Germany
- 3Department of General, Visceral and Thoracic Surgery, University Medical Center Hamburg-Eppendorf, Germany
- 4Department of Orthopaedics, University Medical Center Hamburg-Eppendorf, Germany
- 5Department of Trauma, Hand and Reconstructive Surgery, University Medical Center Hamburg-Eppendorf, Germany
- 6II. Department of Internal Medicine, University Medical Center Hamburg-Eppendorf, Germany
- Dr J Zustin, Institute of Pathology, University Medical Center Hamburg-Eppendorf, Martinistrasse 52, 20246 Hamburg, Germany; j.zustin{at}uke.uni-hamburg.de
- Accepted 23 January 2009
Abstract
Background: HER-2 is the target for antibody-based treatment of breast cancer (trastuzumab), which is highly successful in both advanced disease and the adjuvant setting. HER-2 can be analysed by fluorescence in situ hybridisation (FISH) for gene amplification or immunohistochemistry (IHC) for protein overexpression.
Aim: As both methods are known to be influenced by previous tissue processing, to analyse the applicability of both FISH and IHC to decalcified bone metastases of breast cancer.
Methods: A tissue microarray (TMA) was constructed from 149 breast cancer bone metastases. Consecutive TMA sections were analysed by FISH (PathVysion) and IHC (HercepTest).
Results: FISH analysis was interpretable in 113 (85.0%) cases. Amplification was seen in 14 (12.4%) interpretable metastases. HER-2 positivity on IHC analysis was 3+ in 9.8% of cases and 2+ in 11.3%. A comparison of the two techniques revealed high concordance. Of the 14 cases of amplification, 10 (71%) showed 3+ IHC staining, two (14%) showed 2+, one (7%) showed 1+, and one (7%) showed 0+. Three of the four amplified cases that did not show 3+ IHC staining had an equivocal FISH result, with a HER-2/centromere 17 ratio of 1.8–2.2. Of the 13 cases that showed IHC 3+ staining, amplification was present in 10 (77%).
Conclusions: HER-2 FISH analysis has an excellent success rate in highly standardised EDTA-decalcified bone metastases, suggesting that this method is easily applicable to decalcified tissues. The high concordance between IHC and FISH suggests that HER-2 IHC may be equally applicable to EDTA-treated tissues as to the usual formalin-fixed tissues.
Footnotes
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Competing interests: None.
