Lynch Syndrome: Inherited Colorectal and Other Cancer Risk

Lynch syndrome is an inherited condition. It comes from changes in genes that normally help your cells repair DNA. When those genes do not work well, errors can build up. That raises the risk of certain cancers.

Lynch syndrome most often raises the risk of colorectal cancer (colon and rectum). It also raises the risk of endometrial cancer, which affects the lining of the uterus. It can raise the risk of some other cancers too. Related cancers often appear at younger ages than usual.

Lynch syndrome raises cancer risk — but knowing about it opens the door to screening that can catch or even prevent cancer.

Your cells have a repair system that fixes small mistakes when DNA is copied. It is sometimes called mismatch repair. Lynch syndrome involves inherited changes in the genes that run this system.

When these genes do not work properly, DNA mistakes pile up faster. Over time, that raises the chance a cell will grow out of control and become cancer.

The change is inherited. So it is there from birth, and it can pass from a parent to a child.

Lynch syndrome makes the body's DNA "spell-check" less reliable, which raises cancer risk.

The two cancers most linked to Lynch syndrome are:

• Colorectal cancer, cancer of the colon or rectum
• Endometrial (uterine) cancer, cancer of the lining of the uterus

Lynch syndrome can raise the risk of some other cancers too, such as ovarian and stomach cancer, among others. One key feature stands out. These cancers often appear earlier in life than they would in the general population.

Cancer can show up in a family for many reasons. But some patterns make an inherited condition like Lynch syndrome more likely. Talk with a doctor or genetic counselor if your family has:

• Several relatives with colorectal or endometrial cancer
• These cancers diagnosed at younger ages, such as colon cancer before 50
• The same person having more than one related cancer
• A mix of colon and endometrial cancer across close relatives

Where possible, testing often starts with a relative who has had cancer. That gives the clearest information for the whole family.

Early ages and repeating patterns of colon and uterine cancer are the classic red flags.

Lynch syndrome is confirmed with genetic testing, usually from a blood or saliva sample. It follows a review of your history by a genetic counselor or doctor.

Sometimes the path starts with the tumor. A person's cancer may be tested for features that suggest Lynch syndrome. If those features turn up, inherited-risk testing follows to see whether the change was passed down.

A positive result means a higher risk of certain cancers. It does not mean cancer is certain. Some people with Lynch syndrome never develop cancer.

The biggest benefit of knowing you have Lynch syndrome is that it changes your screening plan. People with Lynch syndrome usually:

• Start colorectal screening younger than average-risk adults
• Screen more often, usually with colonoscopy

Colonoscopy is especially useful here. It can find and remove polyps before they turn into cancer. So screening can prevent cancer as well as catch it early.

Screening or other steps for endometrial cancer and other related cancers may be advised as well. That depends on the specific gene involved and on your own history.

For Lynch syndrome, earlier and more frequent screening is the main way to lower the danger.

Lynch syndrome is inherited, so a diagnosis carries information for your blood relatives. Siblings, children, and parents may share the same change. They could benefit from testing and a screening plan of their own.

A genetic counselor can help you understand your result and plan your screening. They can also help you think through how to share the news with family. If Lynch syndrome runs in your family, your care team can build a screening schedule that fits your specific risk.