Which cancers are linked to Lynch syndrome?

Lynch syndrome most often raises the risk of colorectal cancer, which is cancer of the colon or rectum, and endometrial cancer, which is cancer of the lining of the uterus.

The list does not stop there. MedlinePlus Genetics also links Lynch syndrome to cancers of the stomach, small intestine, liver, gallbladder ducts, urinary tract, brain, and skin. In women, the risk of ovarian cancer is raised as well.

Age is part of the pattern. In people with Lynch syndrome who develop cancer, it typically occurs in their 40s or 50s, younger than these cancers usually appear.

What is actually broken

Lynch syndrome comes from harmful changes in one of five genes: MLH1, MSH2, MSH6, PMS2, or EPCAM. The first four are mismatch repair genes, often shortened to MMR.

Those genes run a proofreading service. Every time a cell copies its DNA, small mistakes happen. Mismatch repair finds and fixes them. When the system fails, errors pile up much faster than normal, and some of them land in genes that control growth.

That is why the risk spans so many organs. The fault is not in the colon or the uterus. It is in a repair mechanism every cell relies on.

The damage leaves a signature. Tumors that have lost mismatch repair show a pattern called microsatellite instability, and labs can test for it.

Lynch syndrome is typically inherited in an autosomal dominant pattern, which means one altered copy of the gene is enough to raise risk. It runs in families, and it does not skip generations by design.

How it gets found

Increasingly, the tumor speaks first. The National Cancer Institute supports a universal screening approach in which all colorectal cancers are tested regardless of the patient's age at diagnosis. Labs use immunohistochemistry to check whether the MMR proteins are present, or test the tumor for microsatellite instability.

That test is done on the cancer, not on you. An abnormal result is a flag, and it leads to genetic counseling and a blood or saliva test to confirm whether you carry an inherited variant.

Why knowing changes so much

Having Lynch syndrome raises risk but does not make cancer certain. What it does is make surveillance worthwhile in a way it would not be otherwise.

The evidence here is unusually concrete. Colonoscopy every 1 to 2 years in people with Lynch syndrome has been shown to reduce both the number of colorectal cancers and deaths from them. Colonoscopy is not only a test; polyps found during the procedure can be removed on the spot, before they ever become cancer.

Your exact plan should be built around which gene is involved and your family history, since risk differs between the five genes.

What to do

If you have had colorectal or endometrial cancer, ask whether your tumor was tested for mismatch repair proteins or microsatellite instability, and what the result was.

Ask for a referral to genetic counseling if cancers in your family appeared before 50, if several relatives had cancers on the list above, or if one relative had more than one of them.

And if you test positive, tell your blood relatives. Each of them can be tested, and for them the result arrives while there is still time to act on it.