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- Title
False-Positive FISH for HER2 Amplification in a Breast Cancer Owing to Loss of CE P17: A Case Report and Literature Review.
- Authors
Jie Xu; Ettler, Helen; Engbers, Peter
- Abstract
The authors present a case of breast cancer with equivocal status for HER2 protein overexpression by initial immunohistochemistry (IHC). Dual-colour fluorescence in situ hybridization (FISH) of paraffin sections of the tumour showed a HER2/CEP17 ratio of 2.6:1, indicative of HER2 gene amplification. However, this was interpreted as a false-positive test due to a loss of CEP17 in 92% of the cells; this was supported by a negative result on repeat IHC testing. Monosomy 17, as indicated by single CEP17, has been reported in 1-6% of patients with breast cancer and can result in false-positive result on FISH; There have been no national guidelines on how to manage and interpret such findings. The literature suggests that when a possible false-positive result on FISH for HER2 amplification due to a loss of CEP17 is indicated, a confirmation by repeat IHC testing, single-colour FISH, or array comparative genomic hybridization (CGH) can help one to make an accurate interpretation and a final decision on whether the patient is eligible for treatment with trastuzumab. More case reports and large clinical studies would help to correlate FISH with clinicopathological findings and to determine how patients with breast cancer with single CEP17, with or without HER2 gene amplification, respond to treatment with trastuzumab or other drugs.
- Subjects
BREAST cancer; HER2 protein; IMMUNOHISTOCHEMISTRY; FLUORESCENCE in situ hybridization; HER2 gene; CANCER treatment
- Publication
Canadian Journal of Pathology, 2013, Vol 5, Issue 1, p15
- ISSN
1918-915X
- Publication type
Case Study