Lynch syndrome is the most common cause of hereditary colorectal cancer. This syndrome results from changes in your genetic makeup that can allow cancerous cells to grow more easily.

Lynch syndrome significantly increases your risk of colorectal cancer and uterine (endometrial) cancer. But you can also experience other cancer types with this syndrome, including, but not limited to, gastric, brain, and kidney cancers.

This syndrome is hereditary, so identifying the condition can be key to establishing a cancer screening plan.

Read on to find out more about Lynch syndrome, including how it’s diagnosed, and what the long-term outlook is for this condition.

Lynch syndrome doesn’t cause a specific set of symptoms. But it does increase your risk of certain cancer.

The cancer most often associated with Lynch syndrome is colorectal cancer. This type often begins as a polyp, a small growth in the colon.

Symptoms associated with colorectal cancer can include:

  • blood in your stool
  • changes in your stools, such as frequent diarrhea or constipation
  • stomach pain that doesn’t go away on its own or get better with treatment
  • unexplained weight loss

See a medical professional if you start to notice these or other painful or disruptive symptoms related to your stomach and bowel movements.

Lynch syndrome is hereditary, which means that it happens when you inherit certain genetic mutations from one or both of your parents. These mutations affect genes that help protect your organs from certain cancers.

You can receive a mutated copy of one of the genes typically involved in Lynch syndrome (MLHL, MSH2, MSH6, PMS2, and EPCAM) from your biological mother or father. Typically, you’ll also have a non-mutated copy of that gene from the other parent.

If, at any point in your life, you experience a mutation that affects the “normal” gene in a particular organ, such as the colon, it increases your risk of cancer in that organ.

Lynch syndrome increases your risk of experiencing multiple cancer types before age 50. Along with colorectal cancer, Lynch syndrome can increase a person’s risks of cancers that affect the:

Lynch syndrome causes an estimated 4,200 colorectal cancers and 1,800 uterine (endometrial) cancers annually.

It’s also important to gather your family’s history of cancer. If family members have had colorectal or endometrial cancer at an early age (under 50 years old), it’s possible that Lynch syndrome gene mutations run in your family.

Sharing this information with a doctor can help you assess your risk and determine whether you could benefit from genetic or diagnostic testing.

Doctors can diagnose Lynch syndrome through genetic (blood) testing. Through these tests, doctors can identify mutations in one of the following genes:

  • MLH1
  • MSH2
  • MSH6
  • PMS2
  • EPCAM deletion

A doctor will also consider a diagnosis of Lynch syndrome if a person has a tumor commonly associated with the condition.

If you’re diagnosed with colorectal or endometrial cancer before age 50 and have a relative with Lynch syndrome or a relative that also developed cancer at a young age, your doctor may test for Lynch syndrome.

There isn’t a cure for Lynch syndrome yet. Treatment for Lynch syndrome depends on when a doctor detects it and whether you’ve also been diagnosed with cancer.

If a doctor determines you have Lynch syndrome through genetic testing, they’ll likely have you follow a surveillance plan that includes:

  • Colon cancer surveillance. You’ll usually begin undergoing a colonoscopy at regular intervals. This is a test that examines the lining of your colon for pre-cancerous polyps using a thin, lighted tube with a camera on the end. These will typically start at age 20 or 25. These tests may start earlier if you had a family member diagnosed at a young age. You will repeat these tests every year or every two years.
  • Endometrial or ovarian cancer surveillance. If you have a uterus, a doctor may recommend yearly transvaginal ultrasounds to look for tumors, along with a yearly biopsy of your endometrial lining. When you’re older, your doctor may also recommend preventatively removing your uterus, ovaries, and fallopian tubes.
  • Gastric cancer surveillance. You may have regular upper endoscopies to examine the lining of your esophagus and stomach, starting around age 30. This is especially important if you have a family history of gastric cancer or if you’re of Asian ancestry, which increases risk.

In addition to creating a surveillance plan with a doctor, it’s important to avoid lifestyle factors and medical conditions that could increase your risk of cancer. Examples of these risk factors include:

Eating a nutritious diet and engaging in regular physical activity can help reduce these risks.

A person with Lynch syndrome has an estimated 80 percent lifetime risk of colorectal cancer and a 60 percent lifetime risk for endometrial cancer, which is why identifying Lynch syndrome by genetic testing is important.

If a doctor does identify a gene mutation associated with Lynch syndrome or you’re diagnosed with cancer caused by Lynch syndrome, the part of your body where the gene mutation occurs can potentially affect your outlook.

Here are some examples:

  • People with MLH1 and MHS2 variants tend to have a higher risk of developing colorectal cancer compared to other variants. Doctors also tend to diagnose colorectal cancer patients with these variants at a younger age.
  • The risks for gastric and small bowel cancer for those with MLH1 or MSH2 variants range from 8 to 16 percent but is significantly lower for those with MSH6 or PMS2 variants.
  • Those with Lynch syndrome who experienced a brain tumor primarily had the MSH2 variant.

If you have Lynch syndrome and have had colorectal cancer, the risks of your cancer recurring can be high. Recurrence is estimated to be around 23 percent for people who have had a portion of cancerous colon tissue removed.

If you or someone close to you has been diagnosed with Lynch syndrome, here are some resources that can help you learn more and find support:

Lynch syndrome is an inherited syndrome that can cause colorectal and other cancers.

If you have a relative that was diagnosed with colorectal cancer at a young age or has Lynch syndrome, talk with a doctor about your possible risks.

A doctor may recommend genetic testing or further tests to look for genetic mutations as well as other factors that may put you at risk of developing cancers that result from Lynch syndrome.