HER-2/neu amplification detected by fluorescence in situ hybridization in fine needle aspirates from primary breast cancer.
BACKGROUND
The HER-2/neu gene is amplified in 20-30% of human breast cancers and has been shown to have prognostic and predictive value for treatment with chemotherapy, hormone therapy and antibodies against the HER-2/neu domain (trastuzumab). The aim of our study was to evaluate the reliability of HER-2/neu determination by fluorescence in situ hybridization (FISH) on fine-needle aspirates (FNAs) from primary breast cancer patients by comparison with the results obtained by FISH and immunohistochemistry (IHC) on the corresponding histological sections.


METHODS
HER-2/neu amplification was determined by FISH on 66 breast cancer FNAs. Twenty-three and 36 corresponding formalin-fixed, paraffin-embedded sections were assayed by FISH and by IHC, respectively, in order to detect HER-2/neu amplification and HER-2/neu protein expression.


RESULTS
Twenty-seven per cent (18/66) of breast cancer FNAs showed amplification of HER-2/neu by FISH. Paired results by FISH cytology and FISH histology were available in 22 cases. Concordance was 91% (20/22). Paired results by FISH cytology and IHC were available in 36 cases. Concordance was 92% (33/36). Eighteen of 66 breast cancer FNAs were also submitted to flow cytometric DNA analysis. None of the diploid cases showed HER-2/neu amplification by FISH. Six out of the eight aneuploid cases were amplified and two were polysomic.


CONCLUSIONS
HER-2/neu gene amplification can be reliably estimated by FISH on breast cancer FNAs and a good correlation has been found between FISH and IHC results from the corresponding histological sections.
Bozzetti
C
C
Departments of Medical Oncology and Pathology, University Hospital, Parma, Italy. oncologia@ao.pr.it
Nizzoli
R
R
Guazzi
A
A
Flora
M
M
Bassano
C
C
Crafa
P
P
Naldi
N
N
Cascinu
S
S
D001707:Biopsy, Needle; D001943:Breast Neoplasms / Q000453:epidemiology / Q000235:genetics* / Q000473:pathology*; D046508:Culture Techniques; D005260:Female; D005784:Gene Amplification; D018734:Genes, erbB-2 / Q000235:genetics*; D006801:Humans; D007150:Immunohistochemistry; D017404:In Situ Hybridization, Fluorescence / Q000379:methods*; D016612:Paraffin Embedding; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity