HER2/neu, CEP 17,17q11.2q12 amplification
HER2-positive tumors have shown to benefit from Herceptin treatment. Current recommendations for HER2 testing include using FISH as a follow up for all IHC 2+ cases.
Fluorescence in situ Hybridization (FISH)
FFPE tissue is acceptable for FISH analysis. Preferred fixative is 10% neutral buffered formalin. Tissues preserved in B5 fixative or decalcified are usually not suitable for FISH. Tumor sections cut 3-5 µm thick and mounted on positively charged organosilane coated (silanized) slides work well. Request several unstained sections (two for each probe) and one H&E stained slide
4°C to 25°C during transit, but specimens may be transported on refrigerated gel packs. Do not allow the gel pack to come in contact with the specimen. Do not freeze. Extreme temperatures should be avoided.
Improper specimen labeling; Insufficient sample; Inadequate fixation and/or processing
Specimens with amplification of HER2 show a HER2/CEP17 ratio greater than or equal to 2.0. Non-amplified tissue shows a ratio of less than 2.0.
Her2/neu, also known as erbB2 or HER2, plays a key role in the regulation of cell growth. HER2 is over expressed through gene amplification in 25-30% of breast cancer patients. Over expression of HER2 has also been observed in ovarian, endometrial, gastric and salivary gland carcinomas.
Clinical studies have shown that HER2/neu amplification as demonstrated by FISH is a statistically significant and independent predictor of tumor recurrence when compared to other commonly used prognostic markers such as tumor size, grade, patient age at diagnosis and hormone receptor status.