FISH test using HER2 (ERBB2) DNA-probe is used in the detection of amplification of the HER2 (ERBB2) gene that plays a key role in the regulation of cell growth. This gene is amplified in some patients with human breast and gastric cancer. These patients respond well to trastuzumab (Herceptin®) treatment.
Newly-cut fresh breast cancer sections is ideal.
The FISH test is optimal with fresh tissue samples. Tissue sections should preferably be between 4 - 6mm in thickness on coated/positively-charged slides. The optimal fixation time in formalin should be between 6 - 72 hours. An accompanying Hematoxylin and Eosin (H&E) stained slide with the invasive tumour region marked out by a pathologist should be submitted together with at least 3 unstained sections.
Fluorescence In Situ Hybridization using direct-labelled LSI HER2 (ERBB2) and CEP 17 DNA probes are hybridized to target loci and analysed under fluorescence microscopy.
Findings are reported in accordance to the International System for Human Cytogenomic Nomenclature (ISCN, 2020).
ASCO/CAP guidelines - Reference ranges for ERBB2 amplification: 1. Positive - Ratio greater or equal to 2.0. 2. Positive - Ratio less than 2.0 with average ERBB2 copy numbers greater or equal to 6.0 signals/cell. 3. Equivocal - Ratio less than 2.0 with average ERBB2 copy numbers greater or equal to 4.0 and less than 6.0 signals/cell. 4. Negative - Ratio less than 2.0 with average ERBB2 copy numbers less than 4.0 signals/cell. For gastric/GEJ carcinomas, results are positive if the ratio is ≥2.0
3 ~ 9 days
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