Summary: This resource outlines frequently asked questions about biomarker testing for targeted therapy
By JAX Clinical Education | May 2026
Q: What is biomarker testing?
Biomarker testing assesses molecules found in blood, other fluids, or tissue that can indicate when an abnormal process or a disease may be present. Biomarkers can include DNA, RNA, and proteins. In cancer care, testing can analyze hundreds of biomarkers that inform the diagnosis, treatment, and prognosis.
NOTE: Biomarker testing can sometimes be referred to as somatic cancer panels, tumor profiling, tumor molecular tests, cancer genomic tests, and genomic tumor tests.
Q: What is biomarker testing for targeted therapy?
Biomarker testing for targeted therapy assesses biomarkers (e.g., gene variants, fusions, amplifications, protein expression levels) that may predict response to targeted therapies. These therapies may be FDA-approved in the patient’s cancer type, FDA-approved in a different cancer type (off-label), or undergoing testing in clinical trials.
Q: For which patients is biomarker testing for targeted therapy appropriate?
A: Professional guidelines recommend multigene panel–based biomarker testing for patients with metastatic or advanced cancer when more than one biomarker-linked therapy is approved for the disease (e.g., NCCN). Multigene testing is also preferred even when a single biomarker-linked therapy exists, due to tumor-agnostic treatment approvals (e.g., MSI-H, TMB-H, NTRK fusions).
Biomarker testing is now recommended at the initial workup of metastatic disease for many cancer types, rather than waiting for disease progression. For example, guidelines for advanced non-small cell lung cancer recommend biomarker testing before first-line therapy to guide optimal treatment selection (NCCN, 2026).
In some cancers, biomarker testing is also relevant in earlier‑stage disease when biomarker‑linked adjuvant or neoadjuvant therapies are available.
Q: For which patients may biomarker testing for targeted therapy not be useful?
A: Biomarker testing may have lower clinical yield in cancers where few actionable biomarkers have been identified or when available therapies are unlikely to change management.
While biomarker testing was historically less common in early‑stage cancers, its role is expanding as biomarker‑linked therapies are increasingly approved for use in earlier disease settings.
Q: What are the benefits of biomarker testing?
A: Biomarker testing can help identify whether a patient is eligible for targeted therapies, immunotherapies, or biomarker‑directed clinical trials based on the specific molecular make-up of their cancer.
Broad biomarker testing can also reduce the need for multiple sequential single‑gene tests, which can be helpful especially when there is limited tissue available. Use of broad testing has been associated with higher rates of receiving matched targeted therapy compared to patients who receive limited or no testing.
Q: What are limitations of biomarker testing?
A: Biomarker testing provides important information about a cancer, but no single test can capture every relevant biomarker. Cancers are often heterogeneous, meaning different areas of a tumor or different metastatic sites may have distinct molecular features. In addition, a cancer’s molecular profile can change over time as cancer cells grow and divide. As a result, biomarkers identified from one sample taken at a single point in time may not fully reflect the cancer elsewhere in the body or at later stages, and it may not be feasible to sample every site.
Different biomarker testing methods use different types of samples and can help address some of these challenges, but each approach has its own limitations. For example, liquid biopsy testing uses a blood sample and may detect biomarkers shed from cancer cells throughout the body. However, this approach depends on the tumor actively releasing tumor DNA into the bloodstream; when shedding is low, some biomarkers may not be detected.
Because of these limitations, multiple testing approaches or repeat testing may sometimes be needed to more fully evaluate a cancer. For more information, see Understanding Biomarker Testing: Types, Benefits & Limitations.
Q: How is biomarker testing done?
A: Biomarker testing is performed in CLIA-certified laboratories using one or more testing approaches, depending on the biomarkers being assessed. Testing may be performed on tumor tissue obtained from a biopsy or surgical sample, or on circulating tumor DNA (ctDNA) obtained from a blood sample (liquid biopsy).
Q: What are the potential outcomes of biomarker testing?
A: Biomarker testing does not always lead to an immediate change in therapy. When actionable biomarkers are identified, they may help predict response, or lack of response, to specific targeted therapies or immunotherapies. However, the presence of a biomarker does not guarantee that a particular therapy will be effective. In addition, access to recommended therapies may be limited by factors such as clinical trial availability or insurance coverage.
In some cases, biomarker testing does not identify actionable biomarkers linked to an available targeted therapy. Results may also be limited or incomplete, suggesting the need for repeat testing, testing of additional biomarkers, or testing of other tumor sites.
Beyond treatment selection, biomarker testing may provide additional clinical insights, including information about prognosis and diagnosis.
Q: Can biomarker testing for targeted therapy identify individuals with hereditary cancer syndromes?
A: In some cases. Genetic testing for hereditary cancer syndromes (e.g., Lynch syndrome, hereditary breast and ovarian cancer syndrome) typically involves testing a blood or oral sample to identify germline pathogenic variants that are present in every cell of the body and can be passed from parent to child. Germline variants in these hereditary cancer genes increase a person’s chance of developing certain cancers in their lifetime and may also provide additional options for targeted treatment.
Not all types of biomarker testing can determine whether a gene variant is present only in cancer cells (somatic) or in all cells (germline). If the oncologist suspects a variant might be in the germline, further work-up by a genetic specialist or genetic testing for inherited cancer risk may be indicated.
Not all variants associated with hereditary cancer syndromes may be included on biomarker tests. Even when the variants are included on the panel, they may not be reported or may be undetectable. It is important to assess the patient’s personal and family history of cancer to determine whether further evaluation by a genetic expert is warranted, regardless of the results from testing.
Q: What have patient experiences been with biomarker testing so far?
A: Cancer patients consistently report a high willingness and interest but may not understand much about genomics or the implications for their care. Managing patient expectations should be part of the conversation when considering biomarker testing.
Understanding Biomarker Testing: Types, Benefits & Limitations. Defines and compares benefits and limitations of types of biomarker testing for identifying targeted treatments.
Exploring Cancer Biomarker Testing (CME|CNE). Learn about benefits, limitations, and challenges of using cancer biomarker testing.
5 Things to Know About Biomarker Testing (JAX). This 30-minute webinar highlights the key benefits and limitations of various cancer biomarker tests.
Interpreting Cancer Biomarker Testing – When is Additional Testing Needed? (CME|CNE). Learn when additional cancer biomarker testing is indicated for further evaluation of genome-informed therapy.
Indications for Genetic Testing for Inherited Cancer Risk After Biomarker Testing. Provides a quick reference about the factors to consider when determining the appropriateness of genetic testing for inherited cancer risk.
Burkett MS. Molecular testing and precision oncology: An overview. Nursing. 2024;54(12):46-50.
Chakravarty D, Johnson A, Sklar J, et al. Somatic Genomic Testing in Patients With Metastatic or Advanced Cancer: ASCO Provisional Clinical Opinion. J Clin Oncol. 2022;40(11):1231-1258.
DaCosta Byfield S, Bapat B, Becker L, et al. Biomarker Testing Approaches, Treatment Selection, and Cost of Care Among Adults With Advanced Cancer. JAMA Netw Open. 2025;8(7):e2519963.
National Comprehensive Cancer Network. NCCN Clinical Practice Guidelines in Oncology: Non-Small Cell Lung Cancer. Version 5.2026.
All information in this resource is provided for educational purposes only.