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Lynch syndrome: the complete picture across organs | CION Cancer Clinics
Lynch syndrome is an inherited fault in the genes that repair DNA. It is best known for raising the risk of bowel cancer, and of womb cancer in women, but it also affects the stomach, urinary tract, ovaries and other organs. This page sets out every organ involved, how the risks differ between the four genes, and how the checks build up across a lifetime. 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 Lynch syndrome, and why does it affect so many organs?
- Which organs does Lynch syndrome affect?
- How the checks build up as you get older
- The words you will meet, in plain language
- How do the four Lynch genes differ?
- Four things families assume about Lynch syndrome
- What this page cannot tell you
- Common questions about Lynch syndrome
The short answer
What is Lynch syndrome, and why does it affect so many organs?
Lynch syndrome is an inherited fault in one of the genes that proofread DNA and fix copying errors. It raises the risk of bowel cancer most of all, and of womb cancer in women, but it also affects the stomach, small bowel, urinary tract, ovaries and several other organs. It is the most common inherited cause of bowel cancer.
One fault, many organs
The proofreading system works in every cell of the body. When one copy of a repair gene is faulty from birth, any organ whose cells divide often can build up errors faster than usual. That is why the risk is not confined to one place, and why the plan covers more than the bowel.
Why the exact gene matters
Lynch syndrome can be caused by a fault in one of four repair genes, or in a nearby gene that switches one of them off. The risks are not the same for all of them. Knowing which gene is involved decides when checks start, which organs are watched and how closely. It is the first thing your counsellor will look at on the report.
Lynch syndrome raises risk. It is not a cancer diagnosis, and many carriers stay well.Organ by organ
Which organs does Lynch syndrome affect?
The bowel and the womb carry the largest share of the risk. The others are less common but still matter for the plan.
The bowel
Bowel cancer is the best known risk. In Lynch syndrome a polyp can turn into cancer faster than usual, which is why colonoscopy is repeated more often than in anyone else.
What is done
- Regular colonoscopy from early adulthood
- Polyps removed as soon as they are seen
The womb and ovaries
For women, womb cancer is often as likely as bowel cancer, and sometimes more so. Ovarian cancer risk is also raised. Warning signs such as bleeding between periods or after the menopause should never be ignored.
What is discussed
- Gynaecology review and symptom awareness
- Risk-reducing surgery once a family is complete
The stomach and small bowel
Both risks are raised, though less than for the bowel. Some centres offer an upper endoscopy, and testing for the stomach infection H. pylori is widely advised.
Other organs
The urinary tract, pancreas, bile ducts, brain and skin can all be affected. Most of these risks are small, and for several of them no screening test has been shown to help.
A family history of any of these cancers is worth telling your counsellor about.Not sure whether this applies to you?
Ask an oncologistAcross a lifetime
How the checks build up as you get older
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Diagnosis and counselling
Usually after a relative's cancer is tested, or after a tumour stain shows a missing repair protein. A counsellor explains the gene, the risks and what the plan will look like.
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Colonoscopy begins
The starting age depends on the gene. For MLH1 and MSH2 it is often in the twenties. For MSH6 and PMS2 it is usually later. After that it is repeated at short, regular intervals.
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Gynaecology joins the plan
Women are taught which symptoms to report at once and are seen by a gynaecologist. The option of risk-reducing surgery is raised once childbearing is finished.
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Other checks are added where they fit
Upper endoscopy, urine tests or other checks may be added, depending on the gene and on which cancers have appeared in your family.
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The plan is reviewed as evidence grows
Advice on Lynch syndrome changes as research matures. Your plan should be looked at again every so often, not fixed for life at the first visit.
On your report
The words you will meet, in plain language
- Mismatch repair (MMR) genes
- The genes that make the cell's proofreading proteins. Lynch syndrome is a fault in one of them.
- MLH1, MSH2, MSH6, PMS2
- The four repair genes. Each name on a report tells you which one carries the fault, and so which set of risks applies.
- EPCAM
- A neighbouring gene. Certain faults in it switch off MSH2, so they behave much like an MSH2 fault.
- Germline
- Present in every cell from birth, and so able to be passed on. The opposite is somatic, a fault found only inside a tumour.
- Dominant inheritance
- One faulty copy from one parent is enough to raise risk. Each child of a carrier has a one in two chance of inheriting it.
- Penetrance
- How often a fault actually leads to cancer across all carriers. It is never all of them, and it differs from gene to gene.
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Side by side
How do the four Lynch genes differ?
MLH1 and MSH2
MSH6 and PMS2
Higher lifetime risks overall
Lower risks, with PMS2 the lowest
Cancers tend to appear at younger ages
Cancers tend to appear later in life
Colonoscopy usually starts earlier
Colonoscopy usually starts later
MSH2 carries more urinary tract risk
MSH6 carries a notable womb cancer risk
Commonly believed
Four things families assume about Lynch syndrome
"Lynch syndrome is just a bowel cancer problem."
The bowel is the organ most often affected, but not the only one. For many women the womb is at equal or greater risk. A plan that watches only the bowel leaves gaps.
"My bowel cancer was removed, so I no longer need checks."
Removing one cancer does not remove the inherited fault. A new, separate cancer can form in the remaining bowel or elsewhere, so surveillance continues after treatment.
"Every Lynch carrier has the same risk."
Risk depends heavily on which gene is involved, and differs between men and women. Two relatives with different genes, or different sexes, may be given different plans.
"I feel perfectly well, so colonoscopy can wait."
Surveillance exists for people who feel well. Its whole purpose is to find and remove polyps before they cause symptoms. By the time a bowel cancer causes symptoms, it is often more advanced.
Being straight with you
What this page cannot tell you
It cannot give you your own risk figures. Published risks vary widely between studies, between genes and between countries, and much of the research comes from Western families. Indian data is still limited. Your counsellor will explain the range that applies to your gene and your family.
It cannot interpret your report
A report that names a variant in a repair gene needs to be read in full. What your specific variant means is a question for the counsellor who ordered the test. A variant of uncertain significance is not the same as Lynch syndrome and should not change your plan on its own.
Who this does not apply to
Most people with one relative who had bowel cancer at an older age do not have Lynch syndrome. Testing is usually offered when a tumour stain shows a missing repair protein, when cancers appear young, or when several relatives on one side are affected. If none of that fits your family, this page is probably not about you.
Questions we are asked
Common questions about Lynch syndrome
How is Lynch syndrome usually found?
Most often through a relative's cancer. Bowel and womb tumours are now routinely stained for the repair proteins, and a missing protein leads to a blood test for the inherited fault. It can also be found when a family history raises the question.
Can Lynch syndrome be treated away?
No. A gene fault cannot be corrected or reversed. What can be done is to find cancers early, or prevent them by removing polyps and, for some women, by surgery. Many carriers live full lives with the right checks in place.
Does Lynch syndrome change cancer treatment?
It can. Tumours in Lynch syndrome usually have a failed repair system, and such tumours often respond well to certain immunotherapy drugs. The extent of bowel surgery may also be discussed differently. Tumour testing itself is covered on our targeted therapy pages.
Does aspirin help?
A large trial found that regular aspirin reduced bowel cancer in Lynch carriers, and many guidelines now suggest discussing it. The best dose is still being studied, and aspirin is not safe for everyone. Never start it without asking your doctor.
Are men affected differently?
Men share the bowel, stomach, urinary tract and other risks, and their bowel risk may be slightly higher than women's. Some studies also suggest a raised prostate risk with certain genes. Men pass the fault to children exactly as women do.
Should my children be tested?
Lynch syndrome risks start in adult life, so testing usually waits until a child is an adult and can choose. The exception is when both parents may carry a repair gene fault, which needs specialist advice much earlier. Your counsellor will talk you through timing.
Does marrying within the family matter?
It can. If both partners carry a fault in a repair gene, a child could inherit two faulty copies, which causes a much more serious childhood condition. Where marriage within the family is common, tell your counsellor so both sides can be considered.
Where do I start?
Gather any reports you have, including tumour stains and genetic results. Write down cancers on both sides with rough ages. Take them to a genetic counsellor or your oncologist. Call the CION helpline if you are unsure 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
Medical Oncologist
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Sources
- GeneReviews (NCBI) — Lynch Syndrome
- MedlinePlus Genetics — Lynch syndrome
- National Cancer Institute — Genetics of Colorectal Cancer (PDQ) - Health Professional Version
- National Cancer Institute — Genetics of Breast and Gynecologic Cancers (PDQ) - Health Professional Version
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
Colonoscopy every one to two years: why so oftenThe reason bowel checks come round so quicklyUrinary tract surveillance in Lynch syndromeWhat is known, and not known, about checking the kidneys and bladderGastric and small bowel surveillance in LynchWhen an upper endoscopy is offeredSkin findings and Muir-Torre syndromeThe skin growths that can reveal Lynch syndrome
Talk to us
Has someone in your family been told they have Lynch syndrome?
Tell us which gene was named and who in the family has been affected. We will help you understand what it means for you and arrange a counsellor to plan the next steps. One helpline serves every CION centre.