Dr. Bazhenova: Hi. I’m Dr. Lyudmila Bazhenova, a Professor of Medicine and Thoracic Medical Oncologist, from the University of California, San Diego.
Graphic: How do you explain what EGFR-mutated lung cancer is to patients?
Dr. Bazhenova: Some patients with lung cancer will have a mutation or abnormality in the gene called EGFR. There are several types of EGFR mutations, and we basically separate them into three main categories. Number one, and the most common one, is what we call the sensitizing or classical EGFR mutations, and then you can have an atypical EGFR mutation. There is a third category of EGFR mutations called EGFR exon 20 insertions.
About 20% of patients with lung cancer will have an EGFR mutation, and the likelihood of a patient having an EGFR mutation depends on ethnicity. For example, a patient of Asian ethnicity will have a higher likelihood of having EGFR mutations, as well as a prior smoking history. Patients who have never smoked or were former light smokers also have a higher likelihood of having an EGFR mutation.
Graphic: Is EGFR-mutated lung cancer hereditary, and who is most likely to get it?
Dr. Bazhenova: The majority of patients have EGFR-mutated lung cancer that is not hereditary. This is a mutation which is an acquired mutation that you developed while you were living. There is a very small proportion of patients with mutations called T790M, and there are a couple of other rare mutations, which could be hereditary but are uncommon. What causes lung cancer in patients, who either didn’t have a prior smoking history or a light smoking history, we do not really know.
Graphic: How do you detect whether someone has EGFR-mutated lung cancer, and at what point in the diagnosis process would you get tested?
Dr. Bazhenova: There are several ways of determining if your tumor, a lung cancer, has an EGFR mutation. Number one is to get a sample of the tumor, and subject that tumor to something that’s called sequencing; where we extract the DNA from the cancer, and then try to read the DNA, or decipher the DNA, to see if there is a mutation in the EGFR.
The second option is to do something that’s called a liquid biopsy; where you take a sample of blood, and using the same technology, try to extract the DNA from the blood, and then try to decipher the DNA and see if you can find a mutation in the EGFR gene. Those liquid biopsies and tissue biopsies, in my opinion, are complementary because liquid biopsies can be false negative in about 3% of the patients. If the only testing you are doing to find an EGFR mutation is liquid testing, it is not the right approach. Liquid can be false negative in about 30% of the patients, so it is very important that tissue analysis is performed as well.
The second question is when to test patients for the EGFR mutations. Until recently, we were only testing patients for EGFR mutations if they have a stage IV or metastatic disease because our treatments were only approved for patients with stage IV disease. Recently, we had results from a trial showing that adding targeted therapy for patients after surgical resection also improves their survival. So currently, I am testing it for patients with stage II, some stage I patients, and then stage III and stage IV, of course.
Graphic: How does the EGFR testing process work, and what can patients expect?
Dr. Bazhenova: It depends on where you do the biopsy. Let’s say, you have a tumor in the middle of the chest lymph node, something that’s called mediastinal, then your typical biopsy would be through something called bronchoscopy. A camera goes in the trachea, and then at the end of the camera, we have tools that are able to get a needle in there and get a sample of that lymph node.
If you have, for example, a tumor in the liver, or a tumor in the adrenal gland, that will require something that’s called a CT-guided biopsy; where you are in a CT scanner, and looking in the CT scanner, the needle is introduced from the outside in. Usually, those procedures are done under local anesthesia if it’s a CT-guided biopsy, and under general anesthesia if it’s a bronchoscopy. Generally, it is – again, I’m not the patient – but I haven’t heard a lot of complaints from patients that they were very uncomfortable during the biopsy.
Graphic: Is it important for a patient to know whether they have EGFR-mutated lung cancer?
Dr. Bazhenova: Absolutely important. I think it’s paramount for patients with lung cancer to know their molecular status, and the EGFR is not the only molecular abnormality we care about. There are actually 11 molecular alterations that change what we do for patients with lung cancer. There are 11 molecular alterations that affect my management of patients with stage IV lung cancer. Currently, there is one molecular alteration in the EGFR, to be specific, that affects my management in patients with early-stage disease.
I think the reason why it’s important to know if you have a mutation in the EGFR, as well as other mutations, is because it changes your treatment. We have done studies where we took a patient with stage IV lung cancer and compared targeted therapy to EGFR and chemotherapy. We found out that if you get targeted EGFR therapy, it works longer, and your quality of life is also better. So that’s why it’s very important to make sure that your tumor is being tested.
