Medically reviewed by Dr. Doug Blayney on May 1, 2024. This educational article was supported by Lilly.
What is biomarker testing?
Biomarker testing for lung cancer is like detectives searching for clues in a mystery. But instead of looking for fingerprints or footprints, they're looking for tiny signs inside the body called biomarkers. These biomarkers can help doctors understand more about the type of lung cancer someone has and how best to treat it. It's like having a special map that shows the way to the right treatment. By finding these biomarkers, doctors can choose the most effective medicine to fight the cancer. So, biomarker testing is an important tool for lung cancer patients because it helps doctors make smarter treatment decisions with their patients.
What is the difference between biomarker testing and genetic testing?
I have been in the “cancer world” for a while, and I still get confused about the difference between biomarker testing and genetic testing. Here are some simple definitions of the two types of mutations:
Germline mutation (often called a genetic mutation or genetic change): Changes in the genes passed from parents to children, affecting how the body develops and works. In one person, the germline mutations do not generally change over time. Many people are familiar with the breast cancer gene mutations, BRCA1 and BRCA2.
Somatic mutation (often called a biomarker): Changes that occur after birth, affecting only certain parts of the body and not necessarily passed on to future generations. In a cancer, the somatic mutations can change over time, and in different cancer deposits (that is metastases) in the body. For example, in lung cancer, there may be changes in the EGFR genes, the ALK genes, the RET genes or several others.
We spoke with Kimary Kulig, an expert in biomarkers and biomarker testing, who provides individual Biomarker Navigation services to cancer patients as My Biomarker Navigator™. She broke down genetic testing like this:
“Genetic testing, as it's called in the clinic, is really looking at germ line changes in DNA. And what does that mean? Germ line refers to the origin of the DNA being from germ cells. You got an egg from mom, sperm from dad. Those are germ cell lineages. And so, when we talk about genetic testing or germ line mutation testing, we're really looking at what is an inherited gene alteration, a mutation for example, that you got from your parents. And it's in all of your DNA, in all of your cells, in your entire body. It's not just in your tumor.”
Kimary went on to describe biomarker testing like this: “When we talk about somatic mutation testing, we're looking at something that is in the tumor and not in your germ line. So, when you have tumor biomarker testing, you're looking at somatic mutations mostly.”
(Listen to the full podcast episode with Kimary Kulig here).
Why is biomarker testing important for lung cancer patients?
We spoke with Dr. Geoff Oxnard, thoracic oncologist and Vice President, Clinical Development, Global Head, Thoracic Cancer at Loxo@Lilly about why biomarker testing is important for lung cancer patients:
“For lung cancer, the genomic diversity is so crazy in its evolution that precision testing has become an absolutely critical part of how we treat lung cancer.” Dr. Oxnard went on to speak about how finding specific biomarkers increases the ability to target those specific biomarkers with treatments that are much more effective for that subset of patients. “And what we realize is that you could figure out which are those patients by profiling. And so, in fact, you can find the EGFR mutation and therefore say, 'oh, wait, I don't have to guess empirically what the therapy is right for you.' I can actually know based on this fingerprint that if you get an EGFR inhibitor, you're going to have a much more favorable outcome, and I can right size your therapy."
(Listen to the full podcast episode with Dr. Geoff Oxnard here).
What do patients say about biomarker testing?
Aurora Lucas, a lung cancer survivor with an EGFR mutation said that when she first heard the word “mutation” it sounded really scary. But once she realized that having a mutation actually made it easier to find treatments to target her mutation, she was relieved. “When I first heard the word ‘mutation’ I thought of cartoon movies, such as the Hulk. That word is so daunting, and I was already on the edge of having just had a lung cancer diagnosis at age 28. But once my oncologist explained that it would actually help determine the best treatment possible, I felt relief and I was able to breathe. I wouldn't turn into the Hulk, after all.”
(Listen to the full podcast episode with Aurora Lucas here).
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