The short answer
This guide helps readers separate changes found in cancer cells from inherited changes that may be present throughout the body. It supports—but does not replace—individual medical, legal, or coverage advice.
The goal is to separate changes found in cancer cells from inherited changes that may be present throughout the body.
Ask what sample was tested and the purpose of the test.
Clarify whether a tumor finding warrants confirmatory germline testing.
Discuss implications for treatment separately from implications for relatives.
Choose how you want to understand this
The full explanation.
What this guide helps you do
Two very different tests both get called "genetic testing" in cancer care. Mixing them up causes real confusion. Tumor testing looks at changes inside your cancer cells. Inherited testing looks at changes you were born with. These are present in every cell in your body. This guide helps you tell them apart. That way you know what a test can, and cannot, tell you and your family.
Tumor testing: changes inside the cancer
Tumor testing is also called somatic testing. It checks a sample of your tumor tissue for genetic changes. These changes happened during your lifetime. They live inside the cancer cells, not the rest of your body. Doctors order this test to help plan your treatment. Certain tumor gene changes point toward specific drugs. Those drugs work better against that particular cancer.
A tumor test can sometimes turn up a change that looks inherited, just by chance. But a tumor test was not built to answer that question. It does not replace formal inherited testing. If a tumor result raises that possibility, ask directly whether follow-up inherited testing makes sense.
Inherited testing: changes present since birth
Inherited testing is also called germline testing. It uses a blood or saliva sample, not tumor tissue. It looks for specific gene changes you were born with. These are present in every cell in your body, not just the cancer. A doctor or genetic counselor usually orders this. They review your personal and family cancer history first.
This is the test that matters for your blood relatives. If you carry an inherited change linked to cancer risk, your children, siblings, and parents may carry it too. Each of them may want to consider testing for themselves. That is a very different conversation than picking a drug for your current tumor.
Why the distinction matters in practice
Confusing these two tests leads to real mistakes. A negative tumor test does not mean your family is in the clear. It was never built to look at inherited risk in the first place. A positive tumor finding is not automatically something your children need to worry about either. That is only true if follow-up testing confirms it is also in your normal, non-cancer cells.
Questions that improve the conversation
Ask exactly which sample was tested: tumor tissue, or blood or saliva. Ask the purpose of this specific test. Was it guiding your treatment, or checking inherited risk? If a tumor test found something unusual, ask whether it needs confirmatory inherited testing. Ask your team to explain what a result means for your treatment. Then ask, separately, what it means for your relatives. These are genuinely two different topics, not one.
Getting the right specialist involved
A genetics professional, usually a genetic counselor, is the right person for consent conversations. They also handle family-risk questions around inherited testing. They can help you think through who in your family to tell, and when. That conversation carries its own weight, separate from your own treatment decisions.
A simple way to keep them straight
If the sample came from your tumor or biopsy tissue, it is telling your doctor about the cancer, not about you and your family in general. If the sample was a blood draw or a saliva kit taken specifically for genetic testing, it is telling you about your own body and, potentially, your relatives. When in doubt, ask which sample was used. That single question usually clears up which conversation you are actually having.
Safety and scope
This guide cannot diagnose a symptom. It cannot set your personal urgency. It cannot guarantee what insurance will cover. Follow your treating team's instructions for your specific situation. Do not change medicines or treatment based on this page alone.
For immediate danger, contact local emergency services. In the United States, call or text 988 for suicide or mental health crisis support.
Sources
Words to know
Tap any term to see what it means.
Common questions
What is tumor testing?
Tumor testing, also called somatic testing, checks a sample of your tumor tissue for genetic changes that happened during your lifetime. Those changes live inside the cancer cells, not the rest of your body. Doctors order it to help plan treatment, because certain tumor gene changes point toward specific drugs that work better against that cancer.
What is inherited testing?
Inherited testing, also called germline testing, uses a blood or saliva sample rather than tumor tissue. It looks for gene changes you were born with, which are present in every cell in your body. A doctor or genetic counselor usually orders it after reviewing your personal and family cancer history.
Does a negative tumor test mean my family is in the clear?
No. A tumor test was never built to look at inherited risk, so a negative result says nothing about your relatives. A positive tumor finding is not automatically something your children need to worry about either. That is only true if follow-up testing confirms the change is also in your normal, non-cancer cells.
Which test matters for my relatives?
Inherited testing. If you carry an inherited change linked to cancer risk, your children, siblings and parents may carry it too, and each of them may want to consider testing. That is a very different conversation from picking a drug for your current tumor.
How can I keep the two straight?
Look at the sample. If it came from your tumor or biopsy tissue, it is telling your doctor about the cancer. If it was a blood draw or a saliva kit taken specifically for genetic testing, it is telling you about your own body and, potentially, your relatives. When in doubt, ask which sample was used.
Questions to ask your doctor
Being prepared helps you get the most out of your appointments. Save or print these questions.
Tap a question to save it to your list (kept on this device).
Your next step
Turn this guide into a short list for your care team.
Speak With Trained Specialists & Human Navigators
Cancer Explained provides educational guidance, but does not replace trained specialists, social workers, or your medical team.
Talk to a trained cancer information specialist
Free, confidential assistance from NCI Cancer Information Service via phone, chat, or email.
Contact your oncology team
Locate after-hours contact numbers, portal messages, or urgent triage phone lines.
Find a patient navigator
Get one-on-one help with appointments, logistics, translation, and care coordination.
Find a genetic counselor
Discuss inherited mutation risk, family history, and genetic testing options.
Find an oncology social worker
Access emotional counseling, family support groups, and mental health resources.
Find a financial navigator
Locate copay assistance foundations, grant programs, and lodging/travel support.
Find a clinical-trial specialist
Search matching studies and speak with NCI trial information specialists.
Get urgent help
Immediate emergency guidance for fever (>100.4°F during chemo), severe pain, or shortness of breath.
Help Us Improve This Guide
Did this explanation answer your question and help you determine your next step?
Know someone who needs this?
Plenty of people are looking for something like this and do not know where to start. If this would help a friend or someone you love, send it on — we have written an opening line so you do not have to stare at an empty message. You can change every word of it.
Your message is written and sent in your own email or messaging app — we never see who you send it to, and nothing is added to any list.
Plain-language explanation of the published sources cited on this page. AI-assisted, source-checked, not clinician-reviewed.
Sources last checked: 2026-07-22 what this meansLast updated: 2026-08-05Next planned review: 2027-07-22
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.
General education — varies by person. Answers genuinely differ between people. This page explains what commonly varies and points you to your care team 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.
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.
Read more about our editorial process, our use of AI, and our corrections policy.
Spotted a problem? Report an error — a factual mistake, broken or outdated source, confusing wording, or anything that seems unsafe. Please do not include names, medical record numbers, dates of birth, addresses, or other identifying medical information in your report.
After using this page, do you understand what to do next?
Anonymous — we only record the answer, never who gave it.
Related articles
Still have questions?
Educational answers, plain language
Free to print and share