Medical Oncologist
CION Cancer Clinics
CDH1 mutation: which cancers it affects, and how much | CION Cancer Clinics
An inherited CDH1 fault raises the risk of a diffuse stomach cancer that is hard to see on endoscopy, and in women, of lobular breast cancer. The size of the risk depends partly on the family it was found in, which is why figures online disagree. This page explains each risk, when in life it starts to matter, and what this page cannot tell you. At CION Cancer Clinics, our oncologists explain what a gene result means for you and your family, and plan the checks that follow.
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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
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On this page
- Which cancers does a CDH1 fault raise the risk of?
- What is known about each cancer linked to CDH1?
- When in life does each risk start to matter?
- The words you will meet, in plain language
- Why do two CDH1 carriers get different advice?
- What this page cannot tell you
- Four things families assume about CDH1 risk
- Common questions about CDH1 cancer risk
The short answer
Which cancers does a CDH1 fault raise the risk of?
An inherited CDH1 fault mainly raises the risk of two cancers. One is a diffuse type of stomach cancer that is hard to see on a camera test. The other, in women, is lobular breast cancer. Both risks are well above the general population, and neither is a certainty.
Why the numbers you read online disagree
The first studies of CDH1 looked at families chosen because many relatives had died young of stomach cancer. Those families gave very high risk figures. Now that CDH1 is on routine panel tests, many carriers are found in families with little or no stomach cancer. In those families the risk looks clearly lower. Both sets of figures are real. They describe different kinds of family.
Why your family history still matters most
A carrier from a family with several young stomach cancers is usually advised differently from a carrier found by chance with no affected relatives. The gene is the same. The weight given to the risk is not, and that judgement belongs to a genetic team.
What stays the same in every family
Whatever the family looks like, the risk is raised enough that every carrier is offered a plan. That plan covers the stomach and, for women, the breasts.
A CDH1 fault is a statement about risk. It is not a diagnosis of cancer.Organ by organ
What is known about each cancer linked to CDH1?
The evidence is strong for the stomach and the breast. It is much thinner for everything else.
Diffuse stomach cancer
This is the main risk, in men and women alike. The cancer spreads beneath the stomach lining rather than forming a lump, so it can be missed on endoscopy. It can appear at a younger age than ordinary stomach cancer.
Why it matters
- Symptoms often come late
- Surveillance can miss early spots
- Preventive stomach removal is discussed
Lobular breast cancer
Women who carry CDH1 have a substantially raised lifetime risk of this breast cancer type. It grows in lines rather than a lump, which makes it harder to see on a mammogram.
Cleft lip and palate
A few CDH1 families also have children born with a cleft lip or palate. It is uncommon. When it appears alongside stomach cancer in a family, it is a clue that CDH1 may be involved.
Other cancers
A possible link with a rare bowel cancer type has been reported. The studies are small and do not agree. No extra bowel screening is advised on CDH1 alone, beyond what the family history suggests.
Not sure whether this applies to you?
Ask an oncologistAcross a lifetime
When in life does each risk start to matter?
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Childhood
Cancer in childhood is very rare in carriers. Testing children is usually left until the late teens, when surveillance or surgery could start to be discussed.
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Early adult life
Stomach cancer risk begins to rise. This is when carriers are usually offered a first specialist endoscopy and a discussion about preventive surgery.
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Thirties and beyond, for women
Lobular breast cancer risk rises. Breast surveillance, often with MRI, is usually started around this time and continues through middle life.
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Middle and later life
Both risks keep adding up with age. Carriers who kept their stomach stay under regular endoscopy for as long as they choose.
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Across every stage
New symptoms such as ongoing indigestion, feeling full early or weight loss should be reported promptly rather than left for the next planned check.
On your report
The words you will meet, in plain language
- HDGC
- Hereditary diffuse gastric cancer. The name for the family condition caused by a CDH1 fault.
- Diffuse gastric cancer
- A stomach cancer that spreads through the wall in scattered cells instead of forming a lump.
- Signet ring cells
- The cells seen under the microscope in this cancer. The name comes from their shape.
- Lobular breast cancer
- A breast cancer that starts in the milk-producing lobules and grows in thin lines.
- Penetrance
- How often a fault actually leads to cancer across everyone who carries it. For CDH1 it is high, but never all.
- Lifetime risk
- The chance of developing a cancer at some point in life, usually counted up to old age.
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Side by side
Why do two CDH1 carriers get different advice?
Strong family history
Found by chance on a panel
Several relatives had stomach cancer, often young
Few or no relatives had stomach cancer
Risk figures from older family studies apply
Newer, lower risk figures may fit better
Preventive stomach removal is usually advised
Surveillance may be a reasonable choice
Breast surveillance is advised for women
Breast surveillance is still advised for women
Being straight with you
What this page cannot tell you
It cannot give you your own risk figure. Published figures come from studies of mostly European and East Asian families. Indian data are still sparse, and the studies so far are small. What your specific variant means is a question for the counsellor who ordered the test.
It cannot tell you whether surgery is right for you
That decision weighs your family history, your age, your health and your own view of living with or without a stomach. It is made with a genetic team and a surgeon who has done this operation before, over several conversations.
Who this does not apply to
Most people with stomach cancer in the family do not carry CDH1. Stomach cancer is common in parts of India, and most of it is caused by infection, diet and smoking rather than by an inherited gene. If one older relative had stomach cancer and nobody else did, this page is unlikely to be about you. If a CDH1 change was found only inside a tumour, see our targeted therapy pages.
Not sure whether your family history counts? Call the helpline and describe it. You will get an honest answer.Commonly believed
Four things families assume about CDH1 risk
"My endoscopy was normal, so I do not have stomach cancer."
A normal endoscopy is reassuring but not final. Early CDH1 cancers sit under a normal-looking lining and can be missed even by expert teams. This is why preventive surgery is discussed at all.
"Only women need to worry about CDH1."
Men carry the same stomach cancer risk as women. Only the breast risk is limited to women. A father can pass the fault to any of his children.
"The risk is so high that cancer is certain."
The risk is high, not certain. Many carriers, especially those found without a strong family history, never develop stomach cancer.
"Stomach cancer in our family means we must carry CDH1."
Most family stomach cancer is not caused by CDH1. The infection Helicobacter pylori, smoking and diet explain far more cases. A counsellor can tell you whether your pattern fits.
Questions we are asked
Common questions about CDH1 cancer risk
How high is the stomach cancer risk with CDH1?
It is substantially higher than for the general population. The exact figure depends on which studies you use and on your family history. Carriers from families with several affected relatives are thought to face a higher risk than carriers found by chance.
Do men with CDH1 have a breast cancer risk?
No clear raise in male breast cancer has been shown. The breast risk applies to women. Men share the stomach cancer risk fully, and they can pass the fault on to daughters who then carry the breast risk.
Can a CDH1 stomach cancer start at a young age?
Yes. It can appear in early adult life, which is much younger than typical stomach cancer. This is why the stomach plan for carriers starts in young adulthood rather than in middle age.
Does removing the stomach remove the whole risk?
It removes the stomach cancer risk almost entirely, because the organ is gone. It does not change the breast risk in women, which still needs its own surveillance. Surgery is one option among several and is discussed on its own page.
Does Helicobacter pylori make CDH1 risk worse?
It is a known cause of stomach inflammation and of ordinary stomach cancer. Carriers are usually tested for it, and treated if it is found. Whether it changes CDH1 risk itself is not yet clear.
My report says CDH1 variant of uncertain significance. What now?
It means a change was found and nobody yet knows whether it matters. It should not lead to stomach surgery. Ask how you will be told if the laboratory reclassifies it, and keep your family history up to date.
Should my children be tested?
Usually from the late teens, when a young person can take part in the decision and when surveillance or surgery might start to be discussed. A counsellor can talk this through with the whole family first.
Where do I start if a relative has tested positive?
Ask for a copy of their report showing the exact variant. A genetic counsellor can then test you for that one change. Call the CION helpline if you are not sure where to go, 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
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Sources
- GeneReviews (NCBI) — Hereditary Diffuse Gastric Cancer
- MedlinePlus Genetics — CDH1 gene
- MedlinePlus Genetics — Hereditary diffuse gastric cancer
- National Cancer Institute — Genetic Testing for Inherited Cancer Susceptibility Syndromes
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.
Talk to us
Trying to understand what a CDH1 result means for your family?
Bring the report and tell us who in the family was diagnosed and at what age. We will help you reach a genetic counsellor who can explain the risk properly. One helpline serves every CION centre.