Medical Oncologist
CION Cancer Clinics
Exome, genome or panel: which genetic test does what | CION Cancer Clinics
For inherited cancer risk, a multigene panel is usually the right first test. It reads a chosen set of cancer genes deeply and returns results a counsellor can act on. Exome and genome sequencing read far more, but they are mainly used when a panel comes back clear and the family history still looks strongly inherited. This page explains what each one reads and when each makes sense. At CION Cancer Clinics in Hyderabad, our oncologists review your family history with you and guide you to the right genetic counselling and testing.
NG
Medically reviewed by Dr. Naresh GunduConsultant Medical Oncologist · MBBS, DNB (Internal Medicine), DM (Medical Oncology, AIIMS) · last reviewed September 2026, next review due September 2027
17+specialists on panel
15,000+patients treated
35+centres across Telangana & AP
4.8★ / 800+Google rating
On this page
- What is the difference between a panel, an exome and a genome?
- What does each test actually read?
- How does a counsellor decide which test you need?
- The words you will meet, in plain language
- Panel, or exome and genome: how do they compare?
- What this page cannot tell you
- Four things families assume, and what is actually true
- Common questions about panels, exomes and genomes
The short answer
What is the difference between a panel, an exome and a genome?
A panel reads a chosen list of genes already known to raise cancer risk. An exome reads almost every gene in the body. A genome reads nearly all of your DNA, including the long stretches between genes. For most families asking about inherited cancer, the panel is the test that answers the question.
More reading does not mean a clearer answer
Reading more DNA sounds safer. In practice, every extra gene read is another chance of finding a change nobody can yet explain. A panel reads fewer genes, reads each one more thoroughly, and every gene on it has a known link to cancer and a known plan if a fault turns up. That is why counsellors usually start there.
Where exome and genome earn their place
They are mostly used when a panel has come back clear and the family history still looks strongly inherited. They also help when a child or young adult has an unusual mix of problems that no single syndrome explains. For an ordinary question about breast, bowel or ovarian cancer in the family, they are rarely the starting point.
All three tests read inherited DNA from blood or saliva. Testing the tumour itself to choose a medicine is a separate question, covered on our targeted therapy pages.The options, one by one
What does each test actually read?
Think of your DNA as a very long book. The tests differ in how many pages they open, and how carefully they read each one.
Multigene panel
Reads a fixed list of genes, each chosen because it has a known link to cancer. Lists range from a handful of genes to several dozen. Because the list is short, each gene is read many times over, which makes the result more dependable.
Usually suits
- A family history of cancer
- Someone already diagnosed
- A first inherited test
Whole exome
Reads the parts of nearly every gene that carry the instructions for making proteins. That is a small fraction of your DNA, but it is where most known disease-causing faults sit. Any single gene may be read less deeply than on a panel.
Whole genome
Reads almost everything, including the stretches between genes and the switches that turn genes on and off. It is the widest net available. Much of what it reads cannot yet be interpreted with confidence, and it usually costs more and reports more slowly.
A test for one known fault
When a relative already has a confirmed fault, the rest of the family usually needs a test for that exact change and nothing wider. It is quicker, costs less and gives the clearest answer of all.
See testing for one known variant.How the choice is made
How does a counsellor decide which test you need?
-
Your family tree comes first
The counsellor draws out who had cancer, which kind and at roughly what age, on both sides. The pattern points to the genes that matter, and that decides which test makes sense.
-
A known fault in the family narrows it
If a relative already has a confirmed result, you are tested for that one change. No wider test is needed to answer your question.
-
Otherwise, a panel matched to the pattern
A breast and ovarian pattern, a bowel and womb pattern and a mixed pattern each have panels built for them. The counsellor picks one that covers the likely genes without piling on genes of doubtful value.
-
Exome or genome only if the panel leaves a gap
If the panel is clear and the history still looks strongly inherited, a wider test may be discussed. It is a considered second step, usually after a specialist has reviewed the case.
-
The result goes back to the person who ordered it
Whichever test is run, the report is explained by the counsellor who arranged it. What your specific variant means is a question for that person, not for a search engine.
Not sure whether this applies to you?
Ask an oncologistOn your report
The words you will meet, in plain language
- Panel
- A fixed list of genes read together in one test. The report should name every gene on the list, so you can see what was looked at.
- Exome
- The protein-making parts of almost all your genes, read together in one test.
- Genome
- All of your DNA: the genes and the long stretches between them.
- Coverage
- How many times each piece of DNA was read. Deeper coverage makes a missed fault less likely.
- Deletion or duplication
- A missing or extra chunk of a gene. Some tests pick these up well, and some need an extra method to find them.
- Secondary finding
- A fault in a gene unrelated to the reason you were tested. You should be asked beforehand whether you want to hear about these.
Side by side
Panel, or exome and genome: how do they compare?
A multigene panel
An exome or genome
Reads genes chosen for their cancer link
Reads almost every gene, related or not
Each gene read deeply
Each gene often read less deeply
Fewer uncertain results to explain
More uncertain results to explain
Usually costs less and reports sooner
Usually costs more and takes longer
Rarely says anything about other illnesses
Can turn up findings about other conditions
Being straight with you
What this page cannot tell you
It cannot tell you which test your family needs. That depends on who was diagnosed, with what, at what age, and whether anyone has already been tested. A genetic counsellor works that out from your family tree before a sample is ever taken.
It cannot read a report you already hold
If you have a panel, exome or genome report in hand, the gene names on it can mean very different things depending on the exact variant and how it was classified. Bring it to someone qualified to read it rather than looking the variant up online.
Who this does not apply to
Most people do not need any of these tests. One relative diagnosed at an older age, with no young diagnoses and no rare cancers, rarely justifies inherited testing at all. If your oncologist wants to test the tumour to choose a medicine, that is a different question from this page.
Where the evidence is still thin
Studies comparing exome and genome directly with panels for inherited cancer are still limited, and practice differs between countries and laboratories. Expect advice to keep changing as the evidence grows.
Commonly believed
Four things families assume, and what is actually true
"The biggest test must be the best test."
Bigger tests read more, but often read each gene less deeply, and they return more results nobody can yet explain. The right test is the one matched to your family's pattern.
"A genome test reads everything, so it cannot miss anything."
Some kinds of change are still hard to detect, and much of the genome cannot yet be interpreted. A clear genome is not proof that your family carries no inherited fault.
"My exome was normal, so I do not need a cancer panel."
An exome ordered for another reason may not have been read with cancer genes in mind. Ask the counsellor whether your exome actually answered the cancer question before assuming it did.
"An exome from an online lab is the same as one a doctor orders."
The sequencing may be similar. The interpretation, the checking of findings and the follow-up can differ widely. A result with no counsellor behind it leaves the family holding a report nobody has explained.
Questions we are asked
Common questions about panels, exomes and genomes
Which test should I have first?
For most people with a family history of cancer, a multigene panel chosen for the family's pattern. If a relative already has a confirmed fault, a test for that one change is enough. Exome or genome is usually a second step, discussed only when a panel leaves a strong suspicion unanswered.
Is an exome the same as a very large panel?
Not quite. Many laboratories run an exome and then report only the genes on a chosen list, sometimes called a virtual panel. Those genes may be read less deeply than on a dedicated panel, so ask how well the cancer genes you care about were covered.
Why would my doctor advise against a genome test when I am willing to pay?
Because a wider test can create problems it cannot solve. It is more likely to return uncertain results, and it can reveal findings about unrelated conditions. If a panel answers your question, a counsellor will usually recommend the panel, whatever your budget.
Can a panel miss something an exome would find?
Yes, if the fault sits in a gene that is not on the panel. That is why the panel is matched to your family's pattern. If a panel is clear and the history still looks inherited, the counsellor may suggest a wider test, or a newer panel later on.
Do these tests use blood or tumour tissue?
Inherited testing uses blood or saliva, because the question is about what you were born with. Tumour testing looks for changes inside the cancer to guide treatment. It is a different test with a different purpose, and one does not replace the other.
Will an exome or genome tell me about diseases other than cancer?
It can. These are called secondary findings. Before testing, you should be asked whether you want to hear about them. You are allowed to say no, and your choice should be written into the consent form you sign.
How long do results take?
It varies between laboratories and depends on how much is read. Panels usually report soonest and genomes take longest. Ask the laboratory for its current reporting time before the sample is sent, especially if the result will shape a treatment or surgery decision.
Where do I start if I am unsure which test I need?
Write down who in the family had cancer, which kind and roughly at what age, on both sides. Take that list to a genetic counsellor or your oncologist. Call the CION helpline if you are not sure who to approach, and we will point you to the right clinic.
Your Specialists
Meet CION's oncologists. Bring your family history or genetic report to them.
Our medical oncologists see people with a strong family history of cancer, arrange genetic counselling and testing where it fits, and plan the checks that follow.
Medical Oncologist
Dr. C. Raghavendra Reddy
MBBS(Gold Medal), DNB(General Medicine), DM(Medical Oncology)(Gold Medal)
Medical Oncologist
Dr. Bharati Devi Gorantla
MBBS, MD(General Medicine), DM(Medical Oncology)(Adyar,Chennai), ECMO, MRCP SCE(UK)
Medical Oncologist
Dr. Owais Mohammed
MBBS, MD (General Medicine), DrNB (Medical Oncology), ECMO, MRCP SCE (Medical Oncology) (UK)
Medical Oncologist
Medical Oncologist
Want a specific doctor for your case? Mention them when booking.
Book Free ConsultationBook an appointment with our specialist
Share your name and number — we'll call you back within 30 minutes to schedule your consultation.
Sources
- National Cancer Institute — Genetic Testing for Inherited Cancer Susceptibility Syndromes
- MedlinePlus Genetics — What are whole exome sequencing and whole genome sequencing?
- MedlinePlus Genetics — What are the types of genetic tests?
- NHS — Genetic and genomic testing
This page is general information, not a prescription. Do not change or stop any treatment based on what you read here. If anything is worrying you, contact your own treating team — or call our helpline and we will help you reach the right specialist.
Keep reading
Related pages
Multigene panel testing explainedThe usual first test, in more detailWhole exome sequencing explainedWhat an exome reads and where it falls shortWhole genome sequencing explainedThe widest test, and why it is rarely the firstWhy a bigger panel is not always betterThe trade-off between more genes and clearer answers
Talk to us
Not sure which test your family actually needs?
Tell us who in your family was diagnosed and at what age, and we will help you work out whether a panel, a single-variant test or no test at all makes sense. One helpline serves every CION centre.