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EGFR FISH

Also known as: EGFR amplification FISH

Test category:

Oncology - Brain cancer

Use of test

Purpose:

Amplification of the EGFR gene, leading to overexpression, can occur in a number of tumour types. This test has diagnostic and prognostic implications in patients with glial tumours.

Utility:

EGFR amplification is currently most clinically useful in brain malignancies of glial origin where it can assist in classification of the tumour. EGFR amplification is a marker of more aggressive disease, but there is conflicting evidence regarding the utility of this association.

Although EGFR amplification can occur in lung tumours, this test does not currently have clinical utility in these tumours. The appropriate EGFR test for lung cancer is Lung cancer focused gene panel.

Ethical considerations:

This is an assay for non-heritable mutations. It does not raise issues of ethics or consent that are different from most other investigations ordered in the routine care of a patient.

Methodology:

Fluorescent in situ hybridisation (FISH) analysis, using probes to enumerate the EGFR gene. This test is performed on thin sections of tissue, so some cells in the section may be sliced by the process, and only contain some of the regions of interest. Sections may contain bony, fatty or necrotic material, which may interfere with processing and/or analysis. Dense tissue also makes identification of individual cells difficult. The accuracy of the results is dependent on the correct identification of tumour on the sections provided, and the assumption that positive results will be identified by a large proportion of cells within the tumour having a rearrangement.

Requesting the test

Ordering:

This test is usually requested by an oncologist. This test is also part of the Oligodendroglioma/Glioma FISH panel.

Request form:

Download the somatic mutation request form.

Sample required:

Formalin-fixed, paraffin embedded tissue (FFPE) - 15 sections of 4 uM thickness, dried overnight at 37°C onto charged/coated slides.

Special instructions:

Please stain the first section with H&E, and label each slide with patient and block identifiers. Label the unstained sections sequentially (slides 2-15). The request should be accompanied by the somatic mutation request form (above) and a copy of the original histopathology report.

Turnaround time:

5 business days.

Price:

Up to $410.

If more information is required, the requesting clinician can call our laboratory on (07) 3377 8573.

Rebate:

This test is not rebated by Medicare. The laboratory assumes that the patient or client has provided informed financial consent for the test.