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Hereditary diffuse gastric cancer: what it is and who it affects | CION Cancer Clinics
Hereditary diffuse gastric cancer is a rare inherited condition, usually caused by a fault in the CDH1 gene. It raises the risk of a type of stomach cancer that spreads under the lining and is hard to see on a camera test, and in women it also raises lobular breast cancer risk. This page explains which families should ask about it and what happens after a positive result. At CION Cancer Clinics, our oncologists plan screening and care for families with an inherited cancer syndrome, explained in plain words.
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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
- What is hereditary diffuse gastric cancer?
- Which families should think about HDGC?
- What happens once a CDH1 fault is found?
- The words you will meet, in plain language
- Preventive surgery or surveillance: how the two paths compare
- Four things families tell us, and what is actually true
- What this page cannot tell you
- Common questions about hereditary diffuse gastric cancer
The short answer
What is hereditary diffuse gastric cancer?
Hereditary diffuse gastric cancer, or HDGC, is a rare inherited condition that raises the risk of one particular type of stomach cancer. It is usually caused by a fault in a gene called CDH1. Women who carry it also have a raised risk of lobular breast cancer. Most stomach cancer in India is not caused by HDGC.
Why the word diffuse matters
Most stomach cancers grow as a lump or an ulcer that a camera test can see. Diffuse cancer is different. Its cells spread out in small patches under the stomach lining, often without any visible change. That is why an ordinary endoscopy can look completely normal in someone who carries the fault, and why this syndrome is handled differently from other stomach cancer risk.
How it passes through a family
Each child of a carrier, son or daughter, has a one in two chance of inheriting the fault. It does not skip generations, though the cancer may. Relatives can be tested for the exact fault once it has been found in one person, usually the relative who had cancer.
Carrying the fault raises risk. It does not mean cancer is certain.Patterns that raise the question
Which families should think about HDGC?
Genetic testing for CDH1 is usually considered when a family shows one of these patterns. A counsellor makes the final call.
Diffuse stomach cancer at a young age
One person diagnosed with diffuse-type stomach cancer unusually young is enough to raise the question, even with no other cancer in the family.
Stomach cancer in more than one relative
Two or more close relatives with stomach cancer, where at least one was the diffuse type, point towards an inherited cause.
Stomach and breast cancer together
Diffuse stomach cancer and lobular breast cancer in the same family, or in the same person, is a strong signal.
Also worth mentioning
- Lobular cancer in both breasts
- Several relatives with lobular breast cancer
- Cleft lip or palate alongside stomach cancer
Who usually does not need testing
One older relative with ordinary stomach cancer, especially the intestinal type linked to long-standing infection, rarely points to HDGC. Most such families do not need a CDH1 test.
Not sure whether this applies to you?
Ask an oncologistAfter a positive result
What happens once a CDH1 fault is found?
A result session with your counsellor
They explain what your variant means, how confident the laboratory is about it, and what the stomach and breast risks look like for you.
A meeting with a specialist team
A surgeon, a gastroenterologist and a dietitian who know HDGC talk you through the two main paths for the stomach: preventive surgery or close surveillance.
Breast checks for women
Women are offered yearly breast MRI from about the age of thirty. This plan is separate from the stomach decision and continues either way.
Telling the family
Parents, brothers, sisters and grown children can be tested for the same fault. The counsellor gives you a letter to share so they can ask for testing themselves.
On your report
The words you will meet, in plain language
- CDH1
- The gene behind most HDGC. It holds the instructions for a protein that helps cells stick together.
- E-cadherin
- That sticking protein. When cells lose it, they can slip loose and spread under the stomach lining.
- Diffuse gastric cancer
- Stomach cancer that spreads in scattered cells instead of forming a lump. Hard to see on a camera test.
- Signet ring cells
- The look of diffuse cancer cells under a microscope. The phrase often appears on biopsy reports.
- Total gastrectomy
- An operation to remove the whole stomach. The food pipe is joined directly to the small bowel.
- CTNNA1
- A rarer gene that can cause a similar pattern in families where CDH1 testing is negative.
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Side by side
Preventive surgery or surveillance: how the two paths compare
Preventive gastrectomy
Surveillance endoscopy
Removes almost all of the stomach cancer risk
Watches the stomach, but can miss early cancer
One major operation, with recovery over months
A long camera test with many biopsies, usually yearly
Eating changes for life, with smaller, frequent meals
Eating stays the same
Usually advised in early adult life
Often chosen while a person delays or declines surgery
Commonly believed
Four things families tell us, and what is actually true
"Stomach cancer comes from spicy food, so it cannot run in families."
Most stomach cancer is linked to long-term infection with a germ called H. pylori, smoking and salt-preserved food, not to chilli. A small share comes from an inherited fault, and HDGC is one of them.
"My endoscopy was normal, so I do not carry the risk."
Diffuse cancer often hides under a normal-looking lining. A clear camera test does not rule HDGC out. Only a genetic test answers whether you carry the fault.
"Everyone with stomach cancer in the family has this."
HDGC is rare. Most families with a relative who had stomach cancer do not carry a CDH1 fault, and most will not be offered this test.
"Nobody can live without a stomach."
People do live full lives after a total gastrectomy. Meals become smaller and more frequent, some vitamins are needed for life, and weight usually falls at first. It is a big change, and people adapt to it.
Being straight with you
What this page cannot tell you
It cannot tell you whether your family has HDGC, or what your own risk is. That depends on the exact variant, how it is classified and who in your family had which cancer. What your specific variant means is a question for the counsellor who ordered the test.
Where the evidence is thin
HDGC is rare, and most of what is known comes from a small number of large families studied abroad. Risk figures for people found through wider panel testing, with little stomach cancer in the family, look lower than the older estimates. Indian data are very limited. Advice on timing surgery is reviewed as more is learned.
Who this does not apply to
Most people with a relative who had stomach cancer do not need this page. If one older relative had the common intestinal type, a CDH1 test is unlikely to help. If you are being treated for stomach cancer now, the mutation tests on your tumour are a different question, covered on our targeted therapy pages.
If your family has a pattern like the ones above, call the helpline and describe it. Someone will tell you honestly whether a referral is worth making.Questions we are asked
Common questions about hereditary diffuse gastric cancer
Is HDGC common in India?
No. Stomach cancer itself is fairly common in some parts of India, but almost all of it is not inherited. HDGC accounts for a very small share. Indian families with a young diffuse stomach cancer or a stomach and breast pattern are the ones who should ask about it.
Can CDH1 testing be done on the relative who died?
Sometimes. If the hospital still holds a tissue block from their surgery or biopsy, a laboratory may be able to test it. Results from old blocks are less reliable than a fresh blood sample. Ask the hospital where the relative was treated whether the block is still stored.
At what age should children be tested?
Testing is usually offered once a young person can consent for themselves, in the late teens. Surgery, if chosen, is generally discussed in early adult life, so testing much younger does not usually change anything. A counsellor can talk this through with you and your child.
Do men with CDH1 need to act?
Yes. Men carry the same stomach cancer risk and face the same choice between surgery and surveillance. They are not offered breast checks. A man can also pass the fault to each of his children with a one in two chance.
What are the symptoms of diffuse stomach cancer?
Early on there are often none, which is part of the problem. Later it can cause indigestion that will not settle, feeling full quickly, weight loss, vomiting or difficulty swallowing. A carrier should report any of these to their team promptly rather than wait for the next check.
Is preventive gastrectomy the only option?
No. It is the option that lowers stomach risk the most, and guidelines generally recommend it. Some people choose yearly surveillance endoscopy instead, often while they delay surgery for work, marriage or pregnancy. Your team should help you weigh both without pressure.
My CDH1 result is a variant of uncertain significance. What now?
It means the laboratory is not yet sure whether the change matters. It should not lead to surgery on its own. Your plan is based on the family history until the variant is reclassified. Ask how you will be told if that happens.
Where do I start if my family fits one of these patterns?
Write down who had which cancer, what type if it is known, and roughly at what age. Take that list to a genetic counsellor or your oncologist. Call the CION helpline if you are not sure who to approach, and counselling can be arranged in Telugu.
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)
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Sources
- GeneReviews (NCBI) — Hereditary Diffuse Gastric Cancer
- The Lancet Oncology (IGCLC) — Hereditary diffuse gastric cancer: updated clinical practice guidelines
- 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.
Keep reading
Related pages
Why endoscopy often looks normal in HDGCWhy a clear camera test is not the reassurance it seemsThe gastrectomy decision in HDGCWeighing preventive surgery against surveillanceBreast surveillance in CDH1 familiesThe breast checks women carriers are offeredThe CDH1 gene: what it doesThe gene behind the syndrome, in plain language
Talk to us
Does your family's stomach cancer history fit this pattern?
Tell us who had stomach or breast cancer and roughly at what age. We will tell you honestly whether a genetic referral is worth making, and arrange it if it is. One helpline serves every CION centre.