Definition

This FISH test evaluates increase in EGFR gene copy number (amplification and/or chromosome 7 polysomy), separately from EGFR point mutations, and requires standardized scoring (the University of Colorado FISH scoring system). FISH-positive (high copy number) patients have been reported to have longer progression-free survival (6 months versus 3 months) and overall survival (15 months versus 7 months) with cetuximab treatment.

Method

FISH analysis

Accepted sample types

Fresh tumor tissue, FFPE

Description

Response to drug treatment.

Inheritance

Increased EGFR copy number is an acquired (somatic) cytogenetic change in the tumor; it is evaluated independently of mutation status and is not hereditary.

Related Tests

Inheritance Patterns

Describes how a genetic condition is passed on within a family. There are five main patterns

Go to term →

Carrier (Heterozygous / Homozygous)

Why it matters: In autosomal recessive inheritance, when each parent is a carrier (while both appear healthy), the chance of their child being born with the disease is 25% in each

Go to term →

VUS (Variant of Uncertain Significance)

This is the situation where the test has detected a change in the DNA, but the role of this change in the development of disease is unconfirmed.

Go to term →

How to Read a Genetic Test Result (Positive / Negative / VUS)

A genetic test result falls into three main categories

Go to term →

Types of Genetic Tests

A genetic test is a type of medical test that detects changes in genes, chromosomes or proteins. Today there are more than 77,000 genetic tests available.

Go to term →