To detect an EGFR gene mutation in tumor tissue to help guide treatment of non-small cell lung cancer
EGFR Mutation Testing
EGFR Mutation Testing
Also Known As
Epidermal Growth Factor Receptor Mutation Analysis
HER-1
erbB-1
Formal Name
Epidermal Growth Factor Receptor
This article was last reviewed
on
This article waslast modified
on
April 24, 2018.
Were you looking instead for Estimated Glomerular Filtration Rate, also known as eGFR? If so, see the article on eGFR.
At a Glance
Why Get Tested?
When To Get Tested?
When you have been diagnosed with non-small cell lung cancer and your health practitioner is considering treatment with tyrosine kinase inhibitors such as gefitinib and erlotinib
Sample Required?
A sample of cancer tissue obtained during a biopsy
Test Preparation Needed?
None
Accordion Title
Common Questions
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How is it used?
EGFR mutation testing is used primarily to help guide treatment and determine whether someone with non-small cell lung cancer (NSCLC) may benefit from targeted therapy such as with the tyrosine kinase inhibitors (TKIs) gefitinib and erlotinib. This testing detects the presence of specific activating mutations in the EGFR gene in the DNA of cells in tumor tissue.
EGFR-activating mutations can lead to uncontrolled growth of cancer cells. TKIs block the action of EGFR, which inhibits cell growth. If a person's lung cancer has an EGFR mutation, then a TKI may be effective in treating his or her cancer.
An EGFR mutation test may be ordered by itself or as part of a series of tests that also includes KRAS and/or ALK mutation testing. Each of these tests may be used to help determine whether a person's lung cancer will respond to targeted therapy and which type will likely be of most benefit.
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When is it ordered?
EGFR mutation testing is ordered when an individual has been diagnosed with non-small cell lung cancer, especially adenocarcinoma, and the person is a candidate for treatment with an EGFR inhibitor.
Currently, if EGFR mutation testing is performed as part of a series of tests, KRAS mutation testing is usually done first. If the tumor is negative for KRAS, then EGFR mutation testing may be done, and if that is negative, then a test for ALK mutation may be performed.
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What does the test result mean?
If KRAS mutation testing is performed and indicates that the tumor lacks a KRAS mutation, then the affected person is likely to respond to an anti-EGFR drug therapy (tyrosine kinase inhibitor, TKI). If the tumor has a KRAS mutation, then it is unlikely to harbor an EGFR mutation or respond to anti-EGFR drug therapy. (In non-small cell lung cancer, EGFR and KRAS mutations are mutually exclusive—the tumor can have one or the other but not both.)
If EGFR mutation testing indicates that an EGFR-activating mutation is present in cancer tissue, then the affected individual is likely to respond to therapy that targets EGFR. If the tumor is negative for an EGFR mutation, then the person is not likely to respond to a tyrosine kinase inhibitor. ALK mutation testing may then used to determine whether the person's tumor would be likely to respond to an ALK kinase inhibitor.
A person could have a negative test result if the tumor tissue sample is insufficient and/or when there are insufficient cancer cells present that contain the mutation. Additionally, there may be EGFR mutations present that are not detected by this testing.
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Is there anything else I should know?
If a patient has already been exposed to a tyrosine kinase inhibitor and is showing signs of resistance to the medication, the health practitioner may order tests that look for specific EGFR resistance mutations.
In addition to non-small cell lung cancer, there is an increased amount of EGFR present in other types of cancer. Some examples include colon cancer, glioblastoma (a type of brain cancer), and cancers of the head and neck, breast, and pancreas. This can be due to amplification and over-expression of the receptor that leads to excessive signaling for growth. Tumors that have increased EGFR protein tend to grow more aggressively, are more likely to metastasize, and are more resistant to standard chemotherapies.
EGFR blocking agents are also routinely used for treatment of metastatic colon cancer and are used with some head and neck cancers.
The utility of EGFR inhibitors and their correlation with EGFR mutations in different types of cancers has yet to be fully established. The role of testing for certain EGFR gene mutations and the mutations' affect on a person's responsiveness to treatment continues to be explored.
EGFR mutation testing is not available in every laboratory. If a health practitioner sends a sample to a reference laboratory, the results may take a few weeks before they are available.
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Can I have my blood tested for EGFR mutations?
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What is the difference between EGFR, also known as Her-1, and Her-2/neu?
EGFR and Her-2/neu are both members of the same family of cell membrane receptors. When either EGFR or Her-2/neu is significantly increased in a cancer, it indicates a more aggressive tumor and a poorer patient prognosis. The primary differences between EGFR and Her-2/neu are that they are ordered to help evaluate different types of cancer and that the drugs that have been developed to target them are specific for that particular receptor, EGFR or Her-2/neu. Her-2/neu is used for evaluating breast cancer.
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Are there other types of testing performed to evaluate EGFR in tumors?
There is a test available that looks at the genetic level for gene amplification; it evaluates the number of copies of the gene present. Sometimes tests for EGFR gene amplification are used to determine the likely course (prognosis) of cancer of the head and neck. Tumors with amplified EGFR tend to grow more aggressively, are more likely to metastasize, and are more resistant to standard chemotherapies. People with these tumors tend to have a poorer outcome.