HER2 FISH (ERBB2)

Formalin-fixed, paraffin-embedded tissue blocks; fixed in 10% neutral-buffered formalin for at least 6 hours, and not more than 72 hours. Tissue should be prepared in sections at 4 microns thick. Sections should be mounted on the positive side of an organosilane-coated slide in order to minimize detachment of the tissue from the slide during FISH assay.

HER2 (c-erbB-2) oncoprotein is a 185 kDa transmembrane tyrosine kinase receptor which is overexpressed in 10-20% of breast cancers and 15-20% of gastric cancers, primarily through gene amplification. It is a prognostic and predictive marker, and HER2 status is tested in all cases of invasive breast carcinoma and in a subset of gastric cancers to determine the use of trastuzumab (Herceptin) and other HER2-targeted therapies. The HER2 fluorescent in situ hybridization (FISH) assay evaluates for HER2 gene amplification using a dual probe system targeting the HER2 gene and the chromosome 17 centromere. Alternative FISH probes for separate loci on chromosome 17 are used in cases that display features of polysomy for chromosome 17.

Room temperature or refrigerated. Ship in cooled container during summer months.

Tissue not verified for the presence of invasive carcinoma, carcinoma in situ, and specimens fixed in fixatives other than formalin are not acceptable. Surgical pathology report should be included. Decalcification compromises the specimen quality, recomend EDTA decal.

10 years FFPE

Only tissue that is clearly invasive carcinoma (established by histopathologic criteria) should be tested. Selection of tissue for the FISH assay should be performed by a pathologist.