Definition

EGFR exon 18 mutations are found in about 3 to 5% of EGFR mutation-positive NSCLC patients; the most common variant is G719X (75.6%), followed by E709X (15.9%). These mutations affect the kinase domain of EGFR, leading to ligand-independent activation of the receptor; they are associated with higher sensitivity to second-generation TKIs (afatinib, neratinib) compared with first/third generation.

Gene/Region Examined

EGFR Exon 18, EGFR Exon 19, EGFR Exon 20, EGFR Exon 21

Method

DNA analysis

Accepted Sample Types

Fresh tumor tissue, FFPE

Description

Response to drug therapy.

Inheritance

EGFR exon 18 mutations are acquired (somatic) mutations in tumor tissue.

Related Tests

Inheritance Patterns

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

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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

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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.

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

A genetic test result falls into three main categories

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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.

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