The epidermal growth factor receptor (EGFR) is a protein that sometimes appears in high amounts on the surface of cancer cells and helps them grow.12
Some lung cancer cells have a DNA mutation that affects the EGFR. This is known as having a tumour that is EGFR mutation-positive.23
Mutated EGFRs show an increased rate of uncontrolled tumour growth, which can speed up the cancer’s progression.23
Importance of knowing mutation status
It is important to know the EGFR mutation status because it can help doctors select the most appropriate treatment for a patient.
Cancer cells with mutated EGFRs (mutation-positive) are constantly signalling the tumour to grow and are therefore, very sensitive to cancer treatments known as targeted therapies such as the Epidermal Growth Factor Receptor Tyrosine Kinase Inhibitor (EGFR-TKI) therapy.23
In advanced NSCLC, there are two main treatment options: chemotherapy and targeted therapy. Medical studies have shown that patients with EGFR mutation-positive tumours gain more benefit from targeted therapies than with standard chemotherapy,23 while patients with EGFR mutation-negative tumours gain more benefit from chemotherapy than with targeted therapies.23
Factors that may be predictors of EGFR Mutations
There are some factors that may predict how likely an individual is to have an EGFR mutation. For example, EGFR mutations are more likely to be observed in:23
- Patients with adenocarcinomas (the most common subtype of non-small cell lung cancer – about 40% of NSCLC)- Nonsmokers (or ex-light smokers)
- Those of Asian descent
People diagnosed with advanced NSCLC and fit into any of the four groups listed above should talk to their doctor about EGFR mutation testing. The only way to find out if a tumour is EGFR mutation-positive and select the most appropriate treatment for a patient is to have an EGFR mutation test. See EGFR Mutation Testing section for more information.
12. Tests for non-small cell lung cancer. American Cancer Society. 05/16/2016. Available at: https://www.cancer.org/cancer/non-small-cell-lung-cancer/detection-diagnosis-staging/how-diagnosed.html. Accessed 9 Feb 2017.
23. Important information for people with advanced non-small cell lung cancer - EGFR. Quebec Lung Association, Quebec Respiratory Health Foundation. Available at: https://pq.lung.ca/pdf/EGFR/EGFRen.pdf. Accessed 9 Feb 2017.
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 the epidermal growth factor receptor tyrosine kinase inhibitor (EGFR-TKI) therapy.
What is an EGFR mutation test?EGFR mutations can lead to uncontrolled growth of cancer cells.24 An EGFR mutation test is to look for the presence or absence of EGFR mutations in the tumour. It can help determine which treatment options might be best for patients with NSCLC.
Testing for EGFR mutation may be recommended if a patient has the adenocarcinoma sub-type of NSCLC, though other sub-types can also have EGFR mutation.25
How to get tested
If there is enough tissue from the original biopsy of a patient’s tumour, this tissue can be tested. If not, a second biopsy to get enough tissue to test may be needed. Some doctors may also want a second biopsy to see if a patient has developed a new mutation called T790M mutation at the failure of first line EGFR-targeted therapy.25 The T790M mutation will cause resistance to EGFR-targeted drugs.25 See About EGFR T790M Mutation section for more information.
In general, results of an EGFR mutation test are available in 1 to 3 weeks’ time.25
Apart from using tumour tissue for testing, other new approaches are being used, including “liquid biopsy”, such as circulating tumour DNA (ctDNA) test which uses blood to study gene changes.26 These tests help guide treatment decisions when additional biopsies are not possible.
24. EGFR Mutation Testing: The Test. American Association for Clinical Chemistry. July 15, 2016. Available at: https://labtestsonline.org/understanding/analytes/egfr-her1/tab/test/. Accessed 9 Feb 2017
25. New lung cancer treatment possibilities through molecular tumor testing. freetobreathe.org, USA 2016. Available at: http://www.freetobreathe.org/images/uploads/MTTBrochure-2017update.pdf. Accessed 9 Feb 2017.
26. Ma MW, et al. Liquid biopsy” - ctDNA detection with great potential and challenges. Ann Transl Med 2015;3(16):235.
For patients with advanced (metastatic) non-small cell lung cancer (NSCLC) whose tumours have epidermal growth factor receptor (EGFR) mutations, researchers have developed drugs called EGFR tyrosine kinase inhibitors (EGFR TKIs) that specifically target the genetic changes that cause cancer.27
The goal of targeted therapies is to accurately target the individual tumor, which hopefully leads to more effective treatments and less side effects. Targeted therapies work in similar ways in all cancers but certain drugs are more effective in certain subtypes of lung cancer.19
Medical studies have demonstrated that EGFR TKIs such as gefitinib, erlotinib and afatinib are effective first-line treatment options in patients with EGFR-mutated (EGFR-positive) non-small cell lung cancer.28
19. Targeted therapy for lung cancer - A guide for the patient. Lung Cancer Alliance. 2016. Available at: http://www.lungcanceralliance.org/Educational%20Materials/Targeted%20Therapy_Brochure_dig.pdf. Accessed 9 Feb 2017.
27. Gerber DE. EGFR Inhibition in the Treatment of Non-Small Cell Lung Cancer. Drug Dev Res. 2008;69(6):359–372.
28. Haaland B, et al. Meta-analysis of first-line therapies in advanced non-small-cell lung cancer harboring EGFR-activating mutations. J Thorac Oncol. 2014;9(6):805-181.
For patients who are diagnosed with advanced lung cancer, it is important to talk with your doctor about the type of lung cancer you have and if EGFR mutation testing is recommended for you. If your doctor recommends one of the EGFR TKIs, it is important to discuss the treatment risks and benefits, as well as the expected outcome.
Sample questions to ask your doctor:
- What type of lung cancer do I have?
- What stage is my lung cancer, and has it spread to other parts of my body?
- What are my treatment options?
- Which treatment am I recommend? Why?
- Will my tumour be tested for an EGFR mutation? If not, why?
- What should be done if my tumour is EGFR mutation-positive?
- What should be done if my tumour is EGFR mutation-negative?
- If an EGFR TKI is recommended, what are the benefits and risks/side effects of this treatment?
- How can I get help to manage any side effects?
- When can I start my treatment, and how long will it last?