Epidermal Growth Factor Receptor
EGFR is one of a family of cell membrane receptors that help regulate cell growth, division, survival and death. In a variety of cancers, there is an increased amount of EGFR present in the tumor tissue. 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. Patients with these tumors tend to have a poorer outcome. Consequently, targeting the EGFR is a valuable molecular approach in cancer therapy. EGFR-specific antibodies that bind to the receptor and prevent signaling are used to treat some of the malignancies.
There are two main ways to test tumors for amplified or over-expressed EGFR: one method measures the amount of EGFR protein present; the other looks at the genetic level for gene amplification - it evaluates the number of copies of the gene present.
How is the sample collected for testing?
A sample of cancer tissue is obtained by doing a biopsy. The biopsy procedure required depends on the organ(s) affected.
Is any test preparation needed to ensure the quality of the sample?
No test preparation is needed.
Como o exame é usado?
EGFR testing may be ordered on those diagnosed with cancer, such as colon cancer, non-small cell lung cancer, glioblastoma (a type of brain cancer), and cancer of the head and neck, breast, or pancreas. It is primarily used to help guide treatment of some cancers and to determine whether a patient can benefit from targeted therapy with an antibody to EGFR. Several drugs called “EGFR inhibitors” have been developed to target the action of EGFR. If a person’s tumor has increased amounts of EGFR, then an EGFR inhibitor may be considered as part of the cancer treatment.
The test may also be used as a prognostic marker to help determine how aggressive a cancer is likely to be.
Quando o exame é pedido?
EGFR testing may be ordered as part of an initial workup of particular cancers or performed on those with certain cancers that are not responding to chemotherapy. It may be done at any time, but it requires a sample of the tumor tissue. If a sample is available from a previous biopsy, it can be done on that sample.
O que significa o resultado do exame?
EGFR testing is not diagnostic, but it helps the doctor understand more about the tumor’s characteristics, evaluate a patient’s overall prognosis, and determine treatment options. If testing using either of the methods is positive, then the patient is more likely to have a tumor that is aggressive and resistant to chemotherapy.
Há mais alguma coisa que eu devo saber?
EGFR blocking agents are routinely being used for treatment of colon cancer and are used with some head and neck cancers. Clinical trials are ongoing to study their effectiveness in the treatment of non small cell lung cancer, and their use may soon be considered for breast cancer treatment.
The utility of these EGFR inhibitors and their correlation to EGFR results 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 patient’s responsiveness to treatment is also being explored.
EGFR testing is not available in every laboratory. If your doctor sends your sample to a reference laboratory, the results may take a few weeks to return.
Is there a blood test for EGFR?
Not yet. Researchers have been able to detect excess EGFR, produced by a tumor, in the bloodstream but a clinically useful test is not yet available.
What is the difference between EGFR (Her-1) and Her-2/neu?
EGFR and Her-2/neu are both members of the same family of cell membrane receptors. They are both measured in tumor tissue and evaluated for over-expression or amplification. 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 diagnosis and prognosis of breast cancer.