Medical Oncologist
CION Cancer Clinics
Should young patients with colon cancer have genetic testing? | CION Cancer Clinics
Yes, in almost every case it should be discussed. If colon cancer is found before fifty, you should be offered an inherited gene test as well as the routine test on the tumour. Most young patients will not carry a fault. For those who do, the result can change the operation, the follow-up plan and when brothers, sisters and children start colonoscopy. This page explains how it works. At CION Cancer Clinics in Hyderabad, our oncologists explain colon cancer in plain words and plan care around you and your family.
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Medically reviewed by Dr. Naresh GunduConsultant Medical Oncologist · MBBS, DNB (Internal Medicine), DM (Medical Oncology, AIIMS) · last reviewed October 2026, next review due October 2027
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The short answer
Should you have genetic testing if colon cancer is found young?
Yes, it should be discussed with almost everyone diagnosed before fifty. Two different tests are involved. One looks at the tumour itself and is done for every colon cancer at any age. The other is a blood test that looks for a gene fault you were born with, and young age on its own is a good reason to be offered it.
Why age changes the question
Inherited gene faults tend to cause cancer earlier in life, so a cancer that appears in your thirties or forties is more likely to have one behind it than a cancer found at seventy. Even so, most young patients do not carry an inherited fault. The rise in colon cancer among younger Indians is mostly not explained by genes, as the page on why it is increasing in under-50s explains.
What a result can actually change
For you, it can change how much bowel the surgeon advises removing, which medicines suit your tumour, and how often your colon is checked afterwards. It can also add checks for other organs. For your brothers, sisters and children, it decides whether they need colonoscopy early or can follow ordinary screening.
A test answers a medical question. It is never a judgement on you or on your parents.Two tests, two questions
Which genetic tests is a young patient offered?
People often hear "genetic test" and picture one thing. In colon cancer there are four, and each answers a different question.
The tumour repair test
Done on the biopsy or the removed tumour, it checks whether the tumour's DNA repair system is working. It is called an MMR or MSI test, and every colon cancer should have it.
This tests the tumour, not you.The inherited blood test
A blood or saliva sample is checked for gene faults present from birth, usually with a panel of several bowel cancer genes at once. For young patients many guidelines advise it whatever the tumour result shows.
It looks for
- Lynch syndrome genes
- Polyposis genes such as APC and MUTYH
- Rarer genes linked to bowel cancer
The sorting tests
When the tumour shows a repair fault, extra tumour tests help work out whether it arose by chance in the tumour or points to an inherited cause. The commonest is a BRAF or methylation test on the same tissue.
The family test
Once a fault is found in you, relatives can be tested for that exact fault. It is simpler and clearer than testing them blind, which is why the person with cancer is tested first.
Not sure whether this applies to you?
Ask an oncologistStep by step
How does testing happen after a young diagnosis?
The tumour test on your biopsy
Your oncologist asks the pathology laboratory to run the repair test on tissue already taken. No new procedure is needed. The result goes to the tumour board with your scans.
A conversation before the blood test
A genetic counsellor or your oncologist explains what could be found, what it might mean for relatives, and what you will be told. You can ask questions and take time before you agree.
One blood sample
The sample goes to a genetics laboratory and results usually take some weeks. If the answer could change the operation, the tumour board may wait for it. Otherwise treatment goes ahead.
The result, explained in person
You hear whether a fault was found, none was found, or the laboratory found a change it cannot yet classify. Each leads to a different plan, and none should be read alone.
A plan for you and your family
You get a follow-up schedule that fits the result, and a letter relatives can take to their own doctor. The counsellor helps you decide who to tell first.
On your report
What do the words on a genetic report mean?
- Lynch syndrome
- The commonest inherited cause of colon cancer. It also raises the risk of cancers of the womb, ovary, stomach and urinary tract.
- FAP
- Familial adenomatous polyposis. A fault in the APC gene causes a very large number of polyps, small growths in the bowel lining, from a young age.
- MUTYH polyposis
- A polyp condition that appears only when both parents pass on a fault, so parents are usually well.
- Pathogenic variant
- A gene change known to cause disease. This is what a positive result means.
- Variant of uncertain significance
- A change the laboratory cannot yet classify. It should not change your treatment.
- Lynch-like
- The tumour shows a repair fault but no inherited fault is found. Families are still watched closely.
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Did you know
The tissue from your biopsy or operation is kept by the laboratory as a small wax block. If a tumour test was missed at the time, it can often still be done later on that stored block, without a new procedure.
Being straight with you
What this page cannot tell you
It cannot tell you whether you carry a fault. Only a test can do that, and only after someone has looked at your tumour result and drawn out your family tree on both sides. Online lists of warning signs miss many people who carry a fault, and frighten many who do not.
It cannot read your report
The same gene name can mean very different things depending on the exact change and how it is classified. Bring the report to a counsellor or your oncologist. The page on Lynch syndrome and colon cancer covers the commonest result in more depth.
Who this does not apply to
This page is for people who already have colon cancer. If you are young, well and worried because a parent or sibling had bowel cancer, your route starts with your family history rather than a test on you. If your cancer is in the rectum, the testing is similar but treatment decisions sit with the rectal cancer pages.
Not sure whether a test was done on your tumour? Call the helpline with your biopsy report in hand and someone will check it with you.Questions we are asked
Common questions about genetic testing when young
Does a young diagnosis mean my cancer is inherited?
No. Most people diagnosed young do not carry an inherited fault. Young age makes one more likely than it would be at seventy, which is why testing is offered, but the usual result is that no fault is found. That answer is useful too, because it reassures the family.
Is the tumour test the same as genetic testing?
No. The tumour test looks only at the cancer and tells your doctors how it behaves and which medicines may work. The blood test looks at the genes you were born with. A tumour result can point towards an inherited cause, but only the blood test can confirm it.
My tumour repair test was normal. Do I still need the blood test?
Often yes, if you were diagnosed young. A normal tumour test makes Lynch syndrome less likely, but polyp conditions such as FAP and MUTYH polyposis leave the repair system working. Your oncologist will weigh your age, your polyps and your family history before advising.
Can the result change my operation?
Sometimes. With Lynch syndrome a surgeon may discuss removing more of the colon to lower the chance of a second cancer. With FAP, removing most or all of the colon is usually advised. The tumour board weighs this against bowel function and your own wishes.
Will it change my chemotherapy or immunotherapy?
The tumour repair result matters more here than the blood test. Tumours with a repair fault respond differently to some chemotherapy, and in advanced disease they often respond well to immunotherapy. Your oncologist explains which applies to your stage before treatment starts.
My blood test found nothing. Is my family safe?
Safer, but not free of risk. A close relative of anyone with colon cancer usually starts colonoscopy earlier than the general population, especially when the diagnosis was young. Your doctor will write down when your brothers, sisters and children should begin.
Should my young children be tested now?
For Lynch syndrome, testing usually waits until your child is an adult and can decide. FAP is different, because polyps start early and checks begin in the teenage years. The page on whether your children should be screened goes through both.
Where can I get tested in Hyderabad?
Your oncologist can arrange the tumour test and refer you for counselling and the blood test. The page on genetic counselling in Hyderabad explains what to expect. Call the CION helpline if you are not sure where to begin.
Your Specialists
Meet CION's colon cancer specialists. Bring your colonoscopy, scan or biopsy report.
Our surgical and medical oncologists plan colon cancer care together: which operation, whether chemotherapy is needed, and the follow-up that comes after.
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
Surgical Oncologist
Dr. Muralidhar Muddusetty
MBBS (AIIMS), MS (Surgery) (AIIMS), DNB (Surgical Oncology), MRCS (Edinburgh)
Surgical Oncologist
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Sources
- NICE — Molecular testing strategies for Lynch syndrome in people with colorectal cancer
- National Cancer Institute — Genetic Testing Fact Sheet
- American Cancer Society — Colorectal Cancer Risk Factors
- Cancer Research UK — Risks and causes of bowel cancer
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.
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Send us your biopsy report and tell us your age at diagnosis. We will tell you which tests have been done, which are still worth asking for, and help arrange a referral. One helpline serves every CION centre.