The short answer
After a cancer diagnosis you may be offered two different genetic tests. Tumor (somatic) testing looks at the cancer to guide treatment. Germline testing looks at the DNA you were born with, and it is the only one that tells your blood relatives anything about their own risk.
Tumor testing and germline testing are not the same test; a BRCA change on a tumor report does not tell you whether it was inherited.
Germline testing is recommended for everyone with ovarian, pancreatic, or male breast cancer, and for metastatic prostate cancer, regardless of family history.
A germline result can change treatment options, the scope of surgery, and what your team screens for later.
Most cancer predisposition variants are autosomal dominant, so each parent, sibling, and child has a 50% chance of carrying the same change.
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The full explanation.
Two tests with similar names, asking different questions
After a cancer diagnosis you may be offered genetic testing twice, for two different reasons.
Somatic testing is also called tumor testing, or biomarker testing. It reads the DNA inside the cancer itself. It asks what is driving this particular tumor, and whether a targeted drug exists for it. Those changes arose during your lifetime, in that tissue. They are not in the rest of your body, and you cannot pass them to your children.
Germline testing reads the DNA you were born with. The sample is usually blood or saliva. It asks whether you inherited a change that raised your risk in the first place. If you did, your blood relatives may carry it too.
This is the difference people most often miss. A tumor report that mentions BRCA does not tell you whether that change is inherited. Only germline testing answers that. The National Cancer Institute is explicit: tumor testing does not replace testing for inherited cancer risk. If a tumor test flags something that might be germline, your team may order a separate blood test to confirm it.
Who is usually offered germline testing
National guidelines recommend germline testing for everyone diagnosed with ovarian cancer, pancreatic cancer, male breast cancer, or metastatic prostate cancer. They also recommend it for many people with triple-negative breast cancer, or with colorectal cancer diagnosed before age 50.
Testing is considered in several other situations too. When cancer appears young. When one person has had more than one primary cancer. When several relatives on the same side of the family are affected. Or when a relative already carries a known variant.
In practice, testing is offered far less often than guidelines suggest. NCI reported an analysis of more than a million people with cancer. Only about 7% had germline testing. That included 38% of those with ovarian cancer and 5.6% of those with pancreatic cancer. If no one has raised it and you fit one of these groups, it is reasonable to ask directly.
What a result can change
A germline result can affect your own care in three ways.
- Treatment. Some inherited variants open up specific options, such as PARP inhibitors in BRCA-related ovarian, breast, pancreatic and prostate cancers.
- Surgery and surveillance. Knowing you carry a variant may change how much surgery you choose. It may also add screening at a different site.
- Long-term follow-up. Certain syndromes raise the risk of a second, unrelated cancer. That changes what your team watches for in the years ahead.
It also changes things for people who are not in the room. Most cancer predisposition variants are passed on in a pattern called autosomal dominant inheritance. That means each child, sibling and parent has a 50% chance of carrying the same variant. Your result is what lets them be tested for that one specific change. This is called cascade testing, and it is faster and clearer than starting from scratch.
What the law protects, and what it does not
The Genetic Information Nondiscrimination Act (GINA, 2008) makes it illegal for health insurers to use genetic information to set eligibility, coverage or premiums. It also bars employers with 15 or more employees from using it in hiring, firing, pay or promotion.
GINA does not cover life insurance, disability insurance or long-term care insurance. In most states those insurers may still ask about genetic test results, and act on them. GINA also does not restrict the US military in employment decisions. And it does not apply to employers with fewer than 15 staff. Some states have passed broader laws.
Clinics rarely mention this gap. It is worth knowing before you test, especially if you were planning to buy or increase any of those policies.
How the process usually works
Testing normally runs through genetic counseling, both before and after. The pre-test conversation covers a three-generation family history. It covers which genes the panel includes. It covers what each possible result would, and would not, tell you. It covers cost and coverage. And it ends with written informed consent. Results usually take a few weeks.
Ask for a copy of the full report, rather than a one-line summary. Relatives and future doctors will need the exact gene and variant name. Reports are also easier to get now than they will be years from now.
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Common questions
My tumor test already found a BRCA mutation. Do I still need a blood test?
Often yes. A tumor test cannot reliably tell whether a change is inherited or arose in the cancer during your lifetime. NCI is explicit that tumor testing does not replace testing for inherited cancer risk. If your team wants to know whether relatives are affected, a separate germline test from blood or saliva is what answers that.
Will genetic testing delay my treatment?
Results usually come back in a few weeks, and treatment rarely waits on them unless the result would change the first decision. If timing matters in your case, ask directly whether the result is expected to change what happens next, and when your team needs it by.
Can my health insurer drop me or raise my premiums because of a positive result?
Not for health insurance. GINA prohibits health insurers from using genetic information for eligibility, coverage, or premiums, and bars employers with 15 or more staff from using it in employment decisions. Life, disability, and long-term care insurers are not covered by GINA and in most states may still ask.
What if my test finds nothing?
A negative result means nothing harmful was found in the genes examined. If your family history is strong, that is called an uninformative negative and it does not rule out an inherited cause. Your screening may still follow your family history rather than the test.
Does a positive result mean my children will get cancer?
No. It means each child has a 50% chance of inheriting the variant, and inheriting a variant raises risk rather than guaranteeing cancer. It also means they can be tested for that one specific change and access screening earlier than they otherwise would.
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Written by: Cancer ExplainedSources last checked: 2026-07-30 what this meansLast updated: 2026-08-11Next 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. We do not employ clinicians and do not intend to — our work 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 checked line by line against the sources listed on it. That confirms the sources support what the page says. 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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