Medical Oncologist
CION Cancer Clinics
MSH6 mutation: which cancers, and how much risk | CION Cancer Clinics
An MSH6 fault mainly raises the risk of cancer of the womb lining and the bowel, with smaller risks for the ovary, stomach, small bowel and urinary tract. The risks are real, but lower and later than with other Lynch genes. This page goes organ by organ, explains how risk builds with age, and sets out what can push your own risk up or bring it down. 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 an MSH6 fault make more likely?
- Where the risk sits, and how much it matters
- At what age does MSH6 risk actually start to rise?
- What the risk words on your report mean
- What can push an MSH6 risk up or bring it down
- What this page cannot tell you
- Four beliefs about MSH6 risk, and what is true
- Common questions about MSH6 cancer risk
The short answer
Which cancers does an MSH6 fault make more likely?
An MSH6 fault mainly raises the risk of cancer of the womb lining and of the bowel. It also raises, to a smaller degree, the risk of cancers of the ovary, stomach, small bowel and urinary tract. The risks are real and well above the general population, but lower and later than with the other main Lynch genes, MLH1 and MSH2.
The picture is different for women and men
For women, cancer of the womb lining is often the largest single risk, and in many MSH6 families it is the first cancer anyone is diagnosed with. For men, the bowel is the main concern. Both sexes share the smaller risks in the stomach, small bowel and urinary tract.
Why the numbers you read online do not agree
Early studies looked only at families with many cancers, which made MSH6 look more dangerous than it is. Newer studies follow carriers forward in time and give lower figures. Websites often quote the older ones. Your counsellor will use current estimates from large carrier databases.
A raised risk is a reason for a screening plan. It is not a prediction that cancer will happen.Organ by organ
Where the risk sits, and how much it matters
Not every organ carries the same weight. This is the order in which most counsellors discuss them.
Womb lining
The biggest risk for most women carriers. It tends to show itself early through bleeding that is not normal for that woman, which is why symptom awareness matters so much.
Signs to report
- Bleeding after the menopause
- Bleeding between periods
- Periods that become much heavier
Bowel
Raised for both men and women, though less than with MLH1 or MSH2. Regular colonoscopy finds and removes growths called polyps before they turn into cancer.
Ovary
Raised, but modestly for MSH6. There is no reliable screening test, so this risk mainly shapes the later conversation about surgery once a family is complete.
Stomach, small bowel and urinary tract
Smaller risks, but worth watching. Stomach risk may be higher in families with a history of it and in regions where a stomach infection called H. pylori is common, which includes much of India.
Evidence for breast, prostate and pancreas is mixed. Your counsellor will say whether it applies to your family.Not sure whether this applies to you?
Ask an oncologistAcross a lifetime
At what age does MSH6 risk actually start to rise?
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Childhood and teenage years
Risk from a single MSH6 fault is very low at this stage. That is why children are not usually tested and nothing needs to change for them.
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Twenties
Cancers are still uncommon. This is a good time for an adult child to decide about testing, learn the warning symptoms and give up smoking if they smoke.
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Thirties
Bowel screening usually begins somewhere in this decade for MSH6 carriers, a little later than for other Lynch genes. Women start discussing womb risk with a gynaecologist.
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Forties and fifties
Risk rises more steeply. Many MSH6 cancers, especially of the womb lining, are diagnosed in these decades. Screening that has been running steadily pays off most here.
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Sixties and beyond
Risk keeps building slowly. Screening continues for as long as a person is fit enough to benefit, and the plan is reviewed rather than simply stopped.
Reading a risk figure
What the risk words on your report mean
- Lifetime risk
- The chance of developing a cancer by old age, usually taken to an age in the seventies or eighties. It is not the chance in the next year.
- Cumulative risk
- The chance of developing a cancer by a stated age. It grows as you get older, which is why the same study can quote several figures.
- Penetrance
- How often carriers of a fault actually develop cancer. MSH6 has lower penetrance than MLH1 or MSH2.
- Absolute risk
- Your actual chance, out of every hundred people like you. This is the figure that helps with decisions.
- Relative risk
- How many times higher your risk is than someone without the fault. It sounds alarming but tells you less on its own.
- General population risk
- The background chance for anyone of your age and sex. Every carrier figure should be read against it.
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Your own risk
What can push an MSH6 risk up or bring it down
Can push risk up
Can bring risk down
Several close relatives with Lynch cancers
Regular colonoscopy that removes polyps early
Smoking
Stopping smoking at any age
Carrying a lot of extra weight
Staying active and at a healthy weight
Untreated H. pylori stomach infection
Testing for H. pylori and treating it
Ignoring abnormal bleeding
Surgery on womb and ovaries, when a woman chooses it
Being straight with you
What this page cannot tell you
It cannot give you your own number. Risk depends on your age, your sex, whether you have had cancer before, and what has happened in your family. What your specific variant means is a question for the counsellor who ordered the test.
The evidence has gaps
Most MSH6 risk estimates come from carriers in Europe, North America and Australia. Studies of Indian families are small so far, and differences in diet, stomach infection and access to screening may shift the picture here. Estimates for the rarer cancers rest on small numbers of cases and may change.
Who this does not apply to
These risks apply to people with a confirmed harmful MSH6 variant. They do not apply to a variant of uncertain significance, which should be treated as a normal result until it is reclassified. They also do not apply to relatives who tested negative for the family's known fault.
A result that shows MSH6 loss only in a tumour is a different question, covered under targeted therapy.Commonly believed
Four beliefs about MSH6 risk, and what is true
"Everyone with an MSH6 fault gets cancer."
Many carriers never develop cancer at all. Those who do are often diagnosed early, because regular checks were already in place when it started.
"The figure on the internet is my risk."
Online figures are averages, often from older studies of heavily affected families. Your own risk may be lower, and only a counsellor who knows your history can put it in context.
"Men only need to worry about the bowel."
The bowel is the main concern for men, but stomach, small bowel and urinary tract risks apply to them too. Men also pass the fault to daughters, whose womb risk is significant.
"If I have had one cancer, the risk is used up."
A carrier who has had one Lynch cancer can develop a second, separate one later. Screening of the remaining organs continues after treatment finishes.
Questions we are asked
Common questions about MSH6 cancer risk
Is womb cancer really a bigger risk than bowel cancer with MSH6?
For many women carriers, yes. Large studies show cancer of the womb lining is the most common cancer in women with an MSH6 fault. That is why gynaecology is part of the plan from early on, not an afterthought.
Is MSH6 risk lower than BRCA risk?
They are different genes affecting different organs, so a straight comparison does not help much. What matters is which organs are at risk, when screening should start and what risk-reducing options exist. Each gene has its own plan.
Can I work out my own risk from an online calculator?
Some carrier databases publish risk tables by gene, age and sex, and they are a useful starting point. They cannot account for your family's own history or your past health. Use them to prepare questions for your counsellor, not to make decisions alone.
Does my risk change after bowel or womb surgery?
Yes. Removing an organ removes the risk of cancer starting in it. The other organs still carry their risk, so screening continues for those. Your plan is updated after any major operation or treatment.
Does an MSH6 fault raise breast cancer risk?
The evidence is mixed. Some studies suggest a small increase, and others do not. At present most guidelines do not recommend extra breast screening for MSH6 alone. Women should follow the usual breast screening advice for their age and family history.
Why was my aunt diagnosed so late if this is inherited?
MSH6 cancers often appear later in life than other Lynch cancers. A diagnosis in someone's fifties or sixties fits the pattern of this gene. That is one reason MSH6 families are missed when doctors look only for young diagnoses.
Does eating Indian food change the risk?
There is no evidence that any particular cuisine causes or prevents Lynch cancers. General bowel health advice applies: plenty of fibre, less processed meat, little alcohol and no tobacco. Treating H. pylori infection matters more for stomach risk than diet does.
Should my risk figures be checked again later?
Yes. Estimates for MSH6 have changed as larger studies report, and they will keep changing. Ask for your plan to be reviewed every few years, and after any new diagnosis in the family. Your counsellor can update the advice as evidence improves.
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
- Prospective Lynch Syndrome Database — PLSD: cancer risks for Lynch syndrome carriers
- GeneReviews (NCBI) — Lynch Syndrome
- National Cancer Institute — Genetics of Colorectal Cancer (PDQ) – Health Professional Version
- MedlinePlus Genetics — MSH6 gene
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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