Elsevier

Annals of Oncology

Volume 13, Issue 7, July 2002, Pages 1036-1043
Annals of Oncology

Original article
Breast cancer
Comparison of HER-2 status between primary breast cancer and corresponding distant metastatic sites

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Abstract

Background

The humanized anti-HER-2 monoclonal antibody trastuzumab (Herceptin®) is a new treatment modality for metastatic breast cancer, the efficacy of which is directly correlated with the HER-2 status of the tumour, evaluated either by immunohistochemistry (IHC) and/or by fluorescence in situ hybridisation (FISH). This analysis is generally performed on the primary tumour. There are few data regarding the HER-2 status in the corresponding distant metastases.

Methods

HER-2 status in 107 patients with a primary breast tumour and at least one distant metastatic lesion was analysed by IHC and FISH.

Results

We found similar levels of amplification (25% and 24%) and overexpression (13% and 19%) of HER-2 in primary and metastatic samples, respectively. Among paired primary/metastatic tumours, six (6%) showed discordance by HercepTest™ (n = 100): all six cases showed greater Her-2 overexpression in the metastatic tissue. By FISH (n = 68), five (7%) cases were discordant: two cases were amplified in the primary tumour but not in the metastasis, and three samples showed amplification in the metastasis but not in the primary. Finally, we analysed HER-2 status in different metastatic lesions from 17 patients that had at least two distant metastatic sites. Discordance between different sites from the same patient was 18% by IHC and 19% by FISH.

Conclusions

Between the paired primary tumour and distant metastatic lesions, 94% and 93% of samples had concordant HER-2 status when analysed by IHC or FISH, respectively. These results do not support routine determination of HER-2 on metastatic sites, particularly when FISH results from the primary tumour are available.

Keywords

breast cancer
HER-2
metastatic
primary

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