Medical Oncologist
CION Cancer Clinics
When a tumour result triggers a germline test | CION Cancer Clinics
Some tumour results point to a fault that may have been there from birth. A BRCA or Lynch syndrome gene fault in the tumour, or a missing repair protein in a bowel or womb cancer, usually leads to a blood test. That test shows whether the fault is inherited and whether relatives should be tested. This page explains the common triggers and what happens next. 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
- Which tumour results should lead to a blood test?
- What in a tumour report usually prompts a germline test?
- What happens between the tumour result and the blood test?
- The words you will meet, in plain language
- Which findings usually lead to a blood test, and which do not
- What this page cannot tell you
- Four things families assume about tumour findings
- Common questions about tumour results and blood tests
The short answer
Which tumour results should lead to a blood test?
A tumour result should lead to a blood test when it finds something that is often inherited. The usual triggers are a fault in a gene such as BRCA1, BRCA2 or one of the Lynch syndrome genes, or a repair protein missing from a bowel or womb tumour. The blood test then shows whether the fault was there from birth.
Why a tumour result can point both ways
A tumour test reads the DNA of the cancer. Some faults in it arose during life and stay in the tumour. Those are called somatic. Others were present in every cell from birth, and the tumour simply carries them too. Those are called germline. The tumour test sees both but usually cannot tell them apart.
Why confirming it matters
If a fault is confirmed as inherited, brothers, sisters and children can be tested for that exact fault. Those who carry it can start screening early. Those who do not can stop worrying. Treatment for the person with cancer can sometimes change as well.
This page is about the family question. Tumour results that guide medicines are covered on our targeted therapy pages.The common triggers
What in a tumour report usually prompts a germline test?
No single rule covers every cancer. Your oncologist weighs the finding against your age, cancer type and family history.
A fault in a gene that is often inherited
Some genes turn up in tumours mostly because the person was born with the fault. A finding in one of these usually leads to a blood test.
Typical examples
- BRCA1, BRCA2 and PALB2
- MLH1, MSH2, MSH6 and PMS2, the Lynch genes
- A few rarer genes, depending on the cancer
A missing repair protein
An MMR stain on a bowel or womb tumour that shows a missing protein, not explained by a change that happened only in the tumour, points towards Lynch syndrome.
A fault in a very high share of the DNA
An inherited fault is in every cell, so it tends to show up in a large share of what the lab reads. This is a hint only. It cannot prove the fault was inherited.
The person and the cancer
A finding carries more weight in ovarian, pancreatic or male breast cancer, in someone diagnosed young, or in a family with several affected relatives.
Not sure whether this applies to you?
Ask an oncologistFrom report to blood test
What happens between the tumour result and the blood test?
Your oncologist reviews the report
They check whether the finding is one that is often inherited, and whether the report itself flags a possible germline fault.
You meet a genetic counsellor
The counsellor draws your family tree, explains what a positive or negative result would mean, and asks for your consent. Counselling in Telugu can be arranged.
The person with cancer gives blood
A blood or saliva sample is tested for the gene the tumour pointed to, and often a few related genes. Testing the affected person first gives the clearest answer.
The family is offered testing, if needed
If the fault is confirmed, adult relatives can be tested for that exact fault. The counsellor gives you a letter to share with them.
On your report
The words you will meet, in plain language
- Germline follow-up
- A recommendation to test blood because a tumour finding may be inherited. It is a suggestion, not a result.
- Variant allele frequency
- The share of the DNA read that carries the fault. A very high share can hint at an inherited fault.
- Somatic
- Found only in the tumour. It developed during life and cannot be passed on.
- Germline
- Present in every cell from birth. It can be inherited and passed to a child.
- Confirmatory testing
- The blood test that checks whether a fault seen in the tumour is really inherited.
- Cascade testing
- Testing relatives, one circle at a time, for a fault already confirmed in the family.
Leave a number, we will call you
One field. No form to fill in, and no charge for the call.
Side by side
Which findings usually lead to a blood test, and which do not
More likely to lead to a blood test
Less likely on its own
A BRCA fault in ovarian or pancreatic cancer
A TP53 fault in an older person's lung cancer
MSH2 and MSH6 missing on the stain
MLH1 missing with methylation found
A fault in a very high share of the DNA
A fault in a small share of the DNA
Cancer at a young age, several relatives affected
Cancer at an older age, a quiet family history
Being straight with you
What this page cannot tell you
It cannot tell you whether the fault on your tumour report is inherited. That is the whole point of the blood test. What your specific variant means is a question for the counsellor who ordered the test.
It cannot give you a fixed list
Which tumour findings should trigger a blood test is still being worked out. Expert groups broadly agree on the main genes, but they differ on the rarer ones, and the advice changes as evidence grows. Your oncologist and counsellor apply the current guidance to your case.
Who this does not apply to
Most tumour results do not lead to a blood test. Many faults in tumours are common, acquired changes that say nothing about the family. If your report shows no inherited flag and your family history is quiet, you probably do not need a germline test at all.
If you are unsure whether your report contains a trigger, ask your oncologist one direct question: does anything here need checking on blood?Commonly believed
Four things families assume about tumour findings
"The tumour has a BRCA fault, so the whole family has it."
Only if the blood test confirms it is inherited. Even then, each child or sibling has their own chance of carrying it, and many will not.
"Any gene fault in the tumour means it is hereditary."
Most faults in tumours are acquired during life. Only some genes, in some cancers, lead to a blood test. Your oncologist knows which ones.
"We can test the children straight away."
The person with cancer is tested first. Testing relatives before the fault is confirmed as inherited gives answers that cannot be interpreted. For adult-onset faults, children are usually tested only as adults.
"If the tumour result was important, it would be treated as urgent."
Treatment decisions come first, so the family question can wait weeks without harm. It should not be forgotten, though. Ask about it at a calm visit.
Questions we are asked
Common questions about tumour results and blood tests
My tumour report shows a BRCA2 fault. Is it inherited?
It may be. A BRCA2 fault in a tumour is often inherited, but not always. A blood test on you settles it. Until then, treat the tumour finding as a question, not an answer, and do not start testing relatives.
Why not just test everyone's blood from the start?
For some cancers, such as ovarian and pancreatic cancer, blood testing is often offered to everyone from the start. For others, the tumour result helps decide who benefits. Your oncologist follows the guidance for your type of cancer.
Does the blood test repeat the whole tumour panel?
No. The blood test looks for inherited faults, usually in a smaller set of genes chosen by the counsellor. It may focus on the gene the tumour pointed to, or look at a few related genes at the same time.
What if the blood test does not find the tumour's fault?
Then the fault most likely arose only in the tumour, and relatives do not need testing for it. Their screening is then guided by the family history. Your counsellor will explain what the negative result does and does not rule out.
Will a confirmed inherited fault change my treatment?
Sometimes. For breast, ovarian, pancreatic and prostate cancers, an inherited BRCA fault can open up specific medicines or change surgical choices. Your oncologist will tell you whether it matters for your plan.
Can the blood test be done if I am on chemotherapy?
Usually, yes. Inherited faults are in every cell and do not change with treatment. A few situations, such as a recent blood transfusion or a bone marrow transplant, need a different sample, and your counsellor will advise on those.
The relative who had the tumour test has died. What now?
A stored blood sample or tissue block can sometimes still be tested. If not, well relatives may be tested directly, though the result is harder to interpret. A counsellor will help you choose the most useful route.
Who should I talk to about my tumour report?
Start with your oncologist, who ordered the tumour test. If a possible inherited finding is mentioned, ask for a genetic counsellor. Call the CION helpline if you are unsure who to approach, and someone 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
- National Cancer Institute — Genetics of Breast and Gynecologic Cancers (PDQ) - Health Professional Version
- NCCN — Genetic/Familial High-Risk Assessment: Breast, Ovarian, Pancreatic, and Prostate
- GeneReviews (NCBI) — Lynch Syndrome
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
Tumour-only testing and missing an inherited causeWhy a clear tumour report does not clear the familyMMR staining as a route into Lynch testingThe stain behind most bowel and womb referralsHRD testing and what it says about BRCAA related tumour result that often raises the BRCA questionHow cascade testing worksWhat happens for relatives once a fault is confirmed
Talk to us
Does your tumour report need checking on blood?
Share what the tumour report says and who in the family has had cancer. We will tell you honestly whether a germline test is worth doing, and arrange counselling if it is. One helpline serves every CION centre.