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EGFR amplification (7p11.2) by FISH

Test Code

FP EGFR

Test Synonyms

EGFR (HER1/erb-B1), CEP 7

Associations

Brain, Breast, lung and colon cancer

Methodology

Fluorescence in situ Hybridization (FISH)

Turnaround Time

3-5 days

Specimen Requirements

10% neutral buffered formalin fixed paraffin embedded tissue
5 mm^3 fresh tissue or 3.0 mL (min. 2.0 mL) FNA in MPLN RPMI media

Specimen Stability
Paraffin blocks stable at 18-25°C indefinitely
Fresh tissue or FNA stable at 2-8°C for 72 hours
Storage & Handling

Fresh tissue, FNA or paraffin embedded tissue, ship in a Styrofoam container with a cool/refrigerated pack (Do not allow cool pack to directly contact sample)

Causes for Rejection

Improper fixative; Tissue not fixed; Insufficient tissue; Specimen exposed to extreme temperature

Reference Range

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.

Description

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.

References
  1. Cappuzzo F et al. (2008). EGFR FISH assay predicts for response to cetuximab in chemotherapy refractory colorectal cancer patients. Annals of Oncology 19(4):717-723.
  2. Franco-Hernandez C et al. (2007). Cancer Genetics and Cytogenetics. 173:63-67.
  3. Moroni M et al. (2008). EGFR FISH in colorectal cancer: what is the current reality? The Lancet Oncology - Volume 9, Issue 5 May.