Definition

HER2 (ERBB2) is an oncogene encoding a tyrosine kinase receptor that plays a role in cell growth signaling. Gene amplification and/or protein overexpression is seen in approximately 15 to 20% of breast cancers and in a subgroup of gastric cancers. Confirmation of amplification/overexpression is required before trastuzumab treatment; the response rate is 80 to 90%.

Method

FISH analysis

Accepted sample types

Fresh tumor tissue, FFPE

Description

Response to drug treatment.

Inheritance

HER2 amplification is an acquired (somatic) event in the tumor; unlike hereditary breast cancer predisposition genes (such as BRCA1/2), it does not show germline transmission.

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 →