The short answer
Biomarker testing looks at genes, proteins, and other substances in your cancer. Here is what NCI says about insufficient tissue, liquid biopsy, results with no matching therapy, and retesting.
NCI says biomarker testing looks at genes, proteins, and other substances in your cancer to find its unique pattern.
Not enough tumor tissue in the biopsy sample can prevent testing. A liquid biopsy on blood is one alternative.
Testing may not help if no biomarker matches an available therapy.
Biomarkers can change over time, so your care team may recommend repeat testing if the cancer comes back.
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This page is for people waiting on biomarker test results after a cancer diagnosis. It explains what NCI says about the testing and what to ask your care team.
What biomarker testing is
NCI says biomarker testing looks at genes, proteins, and other substances in your cancer to find its unique pattern. Tests range from checking a single biomarker to looking at many genes at once. The results can help your care team choose treatment.
Why there may be a delay
Ask your care team how long your testing is expected to take and whether it is done in-house or sent to another laboratory. NCI says testing may not be possible if there is not enough tumor tissue in the biopsy sample. If that happens, ask whether a repeat biopsy or a liquid biopsy (a test of blood or other fluids) is an option.
Whether treatment should wait
This depends on your cancer and your symptoms. Ask your care team directly: does my treatment plan depend on these results, and is there any risk in waiting? Do not start, stop, or delay any treatment on your own.
When nothing matches
NCI says testing may not help if the results show no biomarkers that match available therapies. Ask your care team what the plan is, including whether a clinical trial could be an option.
Inherited changes and retesting
NCI says biomarker testing is different from genetic testing for inherited mutations. Some tests may find inherited (germline) changes, which call for genetic counseling. NCI also says biomarkers in your cancer can change over time, and a test gives a snapshot of one moment. Your care team may recommend repeat testing if the cancer comes back.
Sources
Common questions
Should treatment start before the results come back?
It depends on your cancer and your symptoms. Ask your care team directly whether your treatment plan depends on these results and whether there is any risk in waiting. Do not start, stop, or delay any treatment on your own.
They said there was not enough tissue. Did something go wrong?
NCI notes that biomarker testing may not be possible if there is not enough tumor tissue in your biopsy sample. A liquid biopsy, which tests blood or other fluids, may be an option for some people. Ask your care team what applies to you.
What does it mean if nothing matches a treatment?
NCI says testing may not help if the results show no biomarkers that match available therapies. Ask your care team what the plan is, including whether a clinical trial could be an option.
Does this tell me whether my cancer is hereditary?
NCI says biomarker testing is different from genetic testing for inherited mutations. Some tests may find inherited (germline) changes, which call for genetic counseling. Ask your care team.
Questions to ask your doctor
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Written by: Cancer ExplainedSources last checked: 2026-10-16 what this meansLast updated: 2026-10-16Next planned review: 2027-07-30
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How this page was created
Cancer Explained does not originate medical claims. Every page restates guidance already published by the National Cancer Institute, the CDC, the USPSTF and the FDA, in plain language, with the source cited so you can check the original yourself. AI does the translating and organizing; automated checks test claims, citations, clarity and safety before anything publishes, and this is translation and navigation, not clinical judgment. Nothing here is personal medical advice, and no page can account for your particular situation.
Editorial status: Source checked — This page was written with AI assistance and then compared with the sources listed on it, looking for statements those sources do not back up. That check is not a sentence-by-sentence record and can miss errors. It is not a medical review, and it does not confirm the page is complete or right for your situation.
Human medical review: not completed. Pages here are not signed off by a clinician before they publish. That is not an oversight we are quietly working around: we restate published guidance and cite it, so the authority belongs to the source rather than to us, and every page names where its claims come from — you can verify us instead of trusting us. Where a volunteer clinician has reviewed a page, their name and credentials appear on it; where no name appears, no clinician has checked it. We are glad to have reviewers and are recruiting them, and we do not hold pages back waiting for one. Use this site to understand your situation and to ask better questions of the people treating you.
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