What is EGFR-positive Lung Cancer?

In this video, we discuss EGFR-positive lung cancer and how EGFR mutations drive tumor growth, including common mutation types, how testing is done through tissue or liquid biopsy, and why identifying the mutation is key to choosing targeted treatments.

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Read the full video transcript below:

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This video is an overview of EGFR-positive lung cancer. It is part 1 of a 3-part series.

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For patients and families, understanding how lung cancer forms and what the EGFR mutation means can help them make sense of their diagnosis and treatment options.

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Lung cancer happens when cells in the lungs grow in ways they aren’t supposed to. There are different types of lung cancer - the most common is called non-small cell lung cancer, or NSCLC for short. The most common kind of NSCLC is adenocarcinoma. But, not all lung cancers are the same. Some are caused by changes – or mutations – in the DNA of the cancer cells. 

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Even if the cancer looks the same under a microscope, it can behave differently depending on the proteins inside the cells that help control how they grow. One of these proteins is called EGFR, which stands for epidermal growth factor receptor. Normally, EGFR sits on the surface of cells and acts like a light switch, turning cell growth on and off when needed.

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However, sometimes a mutation, or change, in the EGFR gene keeps this light switch stuck in the “on” position. This causes the cells to grow out of control, which can eventually form a cancerous tumor. This is called EGFR-mutant lung cancer.

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There are different types of EGFR mutations. The most common are called exon 19 deletions and L858R mutations, sometimes called Exon 21. An Exon 19 deletion means a small piece of the EGFR gene is missing. An L858R mutation is a tiny change in the gene's code. Both changes make the EGFR protein overactive, which causes cancer cells to grow. There are also less common EGFR mutations, like Exon 20 insertion.  An insertion means extra pieces are added to the gene’s code. There are also other even less common EGFR mutations, in fact, there are around 70 different uncommon EGFR mutations beyond the main ones. Not all EGFR mutations are the same—and because of these differences, they may not all respond to the same treatments. That’s why it is important to know exactly which EGFR mutation is driving the cancer.

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To find out if a tumor has an EGFR mutation, doctors test a sample of the cancer tissue from a biopsy - or sometimes use a blood test called a liquid biopsy, which looks for pieces of tumor DNA in the bloodstream. However, not every tumor sheds enough tumor DNA into the bloodstream to be detected, so a tissue biopsy is still essential in most cases.

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Knowing if a tumor has an EGFR mutation is very important because there are treatments that specifically target those cancer cells. Waiting for results can be stressful, but that information is key to choosing the most effective treatment plan.

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To learn more about treatments for early-stage EGFR-positive lung cancer, watch Part 2, and for advanced stage EGFR positive lung cancer, watch Part 3. To learn more about living with EGFR-mutant lung cancer, watch Part 4.

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This is not medical advice. Talk to your doctor before making any medical decisions.

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