HER2 gene amplification in patients with breast cancer with equivocal IHC results.
J Clin Pathol
; 64(12): 1069-72, 2011 Dec.
Article
in En
| MEDLINE
| ID: mdl-21836036
ABSTRACT
AIMS:
Equivocal human epidermal growth factor receptor 2 protein (HER2) (2+) immunohistochemistry (IHC) is subject to significant interobserver variation and poses a challenge in obtaining a definitive positive or negative test result. This equivocal test result group accounts for approximately 15% of all tumours, and for optimal guidance of HER2 targeted therapy, a further analysis of quantification of gene copy number and amplification status is needed for patients with early or metastatic breast cancer.METHODS:
553 breast-cancer specimens with equivocal HER2 IHC(2+) test results were collected and subsequently centrally retested by chromogenic in situ hybridisation (CISH), and HER2 gene copy numbers per tumour cell nucleus were determined.RESULTS:
Using CISH, 77 of 553 equivocal HER2 IHC(2+) test result cases (13.9% of total) showed high levels of HER2 gene amplification (≥10.0 gene copies per nucleus), and 41 of 553 (7.4% of total) showed low-level HER2 gene amplification (6.0-9.9 gene copies per nucleus). In 73.6% of cases, no amplification of the HER2 gene was shown, and in only 4.9% of cases was an equivocal test result by CISH observed (4.0-5.9 gene copies per nucleus).CONCLUSIONS:
Testing by CISH of all equivocal HER2 IHC(2+) test result provides a definitive guidance in HER2 targeted therapy in 95.1% of cases. A significant proportion (21.3%) of patients with equivocal IHC(2+) test results show amplification of the HER2 gene.
Full text:
1
Collection:
01-internacional
Database:
MEDLINE
Main subject:
Breast Neoplasms
/
Gene Amplification
/
In Situ Hybridization
/
Genes, erbB-2
Type of study:
Clinical_trials
/
Evaluation_studies
/
Guideline
Limits:
Female
/
Humans
Language:
En
Journal:
J Clin Pathol
Year:
2011
Document type:
Article
Affiliation country: