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The importance of biomarker testing
Learn how biomarker testing can help uncover unique biological characteristics that may influence treatment decisions.
5 min read
Key takeaways
Why might two people with the same type of cancer have different treatment plans? One of the reasons could be because they have different biomarkers — measurable features like genes, protein levels, or molecules — that provide information about how a tumor may behave and how it might grow or respond to certain treatments.
Some biomarkers are considered actionable. Actionable biomarkers are measurable signs in the body that have been clinically validated and can be targeted by an approved treatment. Knowing whether these biomarkers are present (or not present) can help doctors make more informed decisions about next steps.
When doctors do biomarker testing, they can use those results to help design a treatment plan that's tailored to each patient.
Biomarker testing overview
Biomarker tests look for indicators like DNA, RNA, proteins, or other features that signal cancer-related changes. These test results can help provide information about how the cancer behaves, and can suggest whether treatments like targeted therapy or immunotherapy may be effective.
Testing can be performed on tumor tissue obtained through a tissue biopsy, or on blood or other body fluids obtained through a liquid biopsy. For more information, see How biomarker testing works.
Biomarkers are classified into different categories based on their role in cancer care. For example, diagnostic biomarkers help identify whether cancer is present and classify the type of cancer, prognostic biomarkers provide insight into how aggressive the cancer may be, and predictive biomarkers provide information on which treatment plans may be appropriate for an individual patient. Because biomarkers can provide such a wide range of information, early testing can help inform treatment decisions sooner and support timely access to more personalized care.
Role of biomarker testing in precision medicine
Precision medicine or personalized medicine refers to treatment that takes individual biologic differences into account. Biomarker testing is a key part of this approach, because it can help identify what makes your cancer unique, including what treatment plans may be more or less effective.
When actionable biomarkers are found, they may point to the use of targeted therapies or immunotherapy. Targeted therapy is a form of personalized medicine that works by acting on specific features, mutations, or substances found in or on cancer cells. Because these treatments are designed to match the cancer’s molecular characteristics, they often focus more directly on cancer cells and may cause fewer side effects than traditional chemotherapy.
New targeted therapies continue to be developed through clinical trials, many of which require biomarker results to determine eligibility. Some trials are designed specifically for cancers with certain mutations. Getting biomarker testing done early can help identify these options if you need them in your treatment journey.
If no actionable biomarkers are found, the results are still valuable. Knowing which biomarkers aren’t present helps identify which treatment plans may or may not work, and allows your care team to focus on appropriate options. Your doctor may also recommend retesting in the future, especially if the cancer changes over time or if new biomarker tests become available.
Alternatives to chemotherapy for cancer treatment
By identifying genetic mutations or specific proteins, doctors can be better informed, helping to identify treatments that target specific features of the cancer, which may have fewer or different side effects compared to traditional chemotherapy. Chemotherapy may still remain part of care, so it’s important to talk to your doctor about what treatment plan is best for you.
Examples of targeted treatments include:
Breast cancer
- HER2-positive breast cancers (overexpression or amplification) are more likely to respond to HER2-targeted treatments.
Melanoma
- The BRAF V600E mutation in melanoma is a predictive biomarker for response to BRAF inhibitors and MEK inhibitors
Lung Cancer
- Mutations in the EGFR gene, such as exon 19 deletions or the L858R mutation, predict a favorable response to EGFR tyrosine kinase inhibitors (TKIs).
- ALK gene rearrangements serve as predictive biomarkers for responsiveness to ALK inhibitors.
Colorectal Cancer
- Colorectal cancers with MSI-H or dMMR may be more likely to respond to immune checkpoint inhibitor therapy.
Bladder Cancer
- FGFR gene alterations in bladder cancer serve as predictive biomarkers for response to FGFR-targeted therapies.
Blood Cancer
- In chronic myeloid leukemia (CML), the BCR-ABL1 fusion gene serves as a crucial biomarker guiding tyrosine kinase inhibitor (TKI) therapy.
Biomarker testing helps personalize your cancer treatment plan
Even when two people have the same type of cancer, their tumors can behave differently. Biomarker testing provides information about the specific characteristics of your cancer, so your doctor can consider more personalized treatment options like targeted therapies or immunotherapy that act on specific features of the tumor, not just the type of cancer you have.
Talk with your doctor about which biomarker tests may be most helpful for your cancer treatment. This discussion guide can help you prepare for that conversation with your care team, so you can advocate for the testing and treatment options that may work best for you.
Planning for biomarker testing: coverage, costs, and logistics
Access to biomarker testing may depend on factors such as insurance coverage, the availability of specific tests, and whether enough tumor tissue is available for testing. Because these factors can affect when and how testing is done, it’s important to discuss them with your care team to understand your options and any potential costs. Ask your care team about:
- Which tests are covered by your insurance and whether prior authorization is needed
- Out-of-pocket costs you may face
- The benefits of testing and which treatment options the results might inform
- How your genetic information will be protected and used
Because biomarkers can provide such a wide range of information, early testing can help inform treatment decisions sooner and support timely access to more personalized care.
To find out more, read “What are cancer biomarkers and what is biomarker testing?”
Correct answer: Because biomarkers can provide such a wide range of information, early testing can help inform treatment decisions sooner and support timely access to more personalized care.
To find out more, read “What are cancer biomarkers and what is biomarker testing?”
Frequently asked questions
When should biomarker testing be done?
Biomarker testing is usually done at the time of diagnosis, or when cancer progresses, to help guide treatment choices. Early testing can help your care team select the most appropriate therapies sooner.
Find out more about when to get tested and why testing early is so important:
Does biomarker testing replace chemotherapy?
No. Biomarker testing does not replace chemotherapy. Biomarkers are measurable signs that show your cancer’s unique characteristics and behavior. Biomarker results can help predict how your cancer may or may not respond to certain treatment plans.
Is biomarker testing available for all cancer types?
No, not all cancers have known biomarkers. Testing is most common in cancers where biomarkers are known to guide treatment plans, such as lung, breast, colorectal, bladder, and some blood cancers.
Are there risks to biomarker testing?
Biomarker testing is generally safe. Risks are usually related to how the sample is collected. For example, a biopsy may cause bleeding or pain. Blood tests carry minimal risk.
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References
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Moore DC, Guinigundo AS. Biomarker-Driven Oncology Clinical Trials: Novel Designs in the Era of Precision Medicine. J Adv Pract Oncol. 2023;14(Suppl 1):9-13. doi:10.6004/jadpro.2023.14.3.16
Yu SH, Kim Ss, Kim S, Lee H, Kang TW. FGFR3 Mutations in Urothelial Carcinoma: A Single-Center Study Using Next-Generation Sequencing. Journal of Clinical Medicine. 2024; 13(5):1305.
Zhou Y, Tao L, Qiu J, et al. Tumor biomarkers for diagnosis, prognosis, and targeted therapy. Signal Transduct Target Ther. 2024;9(1):132. Published 2024 May 20. doi:10.1038/s41392-024-01823-2.