How Does Biomarker Testing Identify Genetic Mutations?
Most genetic mutations related to non-small cell lung cancer are somatic mutations. Biomarker testing is used to determine if any somatic genetic mutations are present. The results of biomarker testing impacts the non-small cell lung cancer treatments selected.
Biomarkers, also known as biological markers, are substances such as genes, proteins, hormones, or other compounds found in cancer cells, surrounding tissues, and bodily fluids such as blood. These molecular markers offer valuable information about the characteristics of cancer.
Lung Biopsy to Collect Tissue Sample for Biomarker Testing
Typically, patients undergo a biopsy to confirm the presence of lung cancer. The tumor cells removed during the biopsy can be used for biomarker testing. Sometimes, this tissue sample can be taken during surgery to remove the tumor. However, if surgery isn't an option, your oncologist may recommend other methods to get a tumor tissue sample. One standard method is a bronchoscopy, which involves using a flexible tube inserted through your nose or mouth and into your lungs to extract tissue.
Once a sample is collected, one or more tests will be performed to identify the presence of any gene mutations. A report is provided that lists any genetic changes and overgrowth of proteins in a “tumor profile.”
Gene Mutations Associated with Non-Small Cell Lung Cancer
Biomarker testing is usually done on the tissue removed from a lung tumor biopsy. If surgery is performed before a biopsy, the tissue removed during the procedure will be used for testing. Several genes are known to be related to genetic mutations found in non-small cell lung cancer:
- TP53 - the most common mutation found in about half of NSCLC patients
- KRAS
- EGFR
- ROS1
- RET
- BRAF
- ALK
- MET
- HER2
- NTRK
Read our blog: Lung Cancer Gene Mutations: What Are They and How Do They Affect Treatment?
Tests Used to Identify Genetic Mutations in Lung Cancer Cells
- Sequencing isn’t as sensitive as other methods but is used as an early test that assesses the entire gene for mutations. Sequencing involves breaking DNA strands into smaller pieces to see if there are changes to any of the genes.
- Allele-specific testing is a faster, less expensive, and more accurate method that can identify mutations in several genes, such as EGFR, MET, BRAF, HER2, and KRAS.
- Next-generation sequencing (NGS) uses computers to identify more mutations than can be found in standard sequencing. The doctors will use blood or tissue samples. It searches for multiple biomarkers at the same time.
- Fluorescence in-situ testing (FISH) is a method for identifying mutations in ALK, ROS1, RET, and other genes.
- Immunohistochemistry (IHC) is another method for identifying mutations in ALK and ROS1. It is faster and less expensive than FISH.
- Liquid biopsies use blood samples to measure tumor cells' DNA and can quickly identify EGFR mutations.
