EGFR (HER1/erb-B1), CEP 7
Brain, Breast, lung and colon cancer
Fluorescence in situ Hybridization (FISH)
*Performed by affiliate laboratory
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 fixative; Tissue not fixed; Insufficient tissue; Specimen exposed to extreme temperature
In a cell with normal copy numbers, two orange signals (EGFR) and two green signals (CEP 7) is observed. Abnormal copy number of the EGFR gene is indicated by three or more copies of the orange signal. Simultaneously, the copy number of chromosome 7 can be quantified by enumeration of the green signals observed within the same cell. Enumeration of both the orange and green signals provide a mechanism for determining EGFR copy number relative to total chromosome 7 copy number.
Sequence alterations of the EGFR gene have frequently been identified in non-small cell lung carcinoma (NSCLC), primarily in those patients who were responsive to Gefitinib, an EGFR tyrosine kinase inhibitor. A higher elevation of EGFR mRNA transcript has been observed in prostate cancers than in benign prostate hyperplasia (BPH) and normal prostate tissues. Colorectal cancer (CRC) patients with high EGFR gene copy number have an increased likelihood to respond to cetuximab therapy. FISH can detect this rearrangement in either interphase or metaphase cells.