Lynch Syndrome Test

Colorectal cancer is the third most common cancer in adults and is the third leading cause of death related to cancer in the United States. 

Colorectal cancer occurs when cells in the colon or rectum start to grow abnormally into a tumor. About 5% of colorectal cancer cases are inherited. These cases are called hereditary colorectal cancer, or HCC. HCC occurs when a cancer gene is passed from the parent to the child. 

People with a family history of colorectal cancer may have a higher risk of developing colorectal cancer. If someone in your family has tested positive for Lynch syndrome, you may be wondering about your cancer risk and what kind of testing you need. Because many people with colon or rectal cancer do not have symptoms right away, it is essential to determine what routine preventive screening options are right for you.

Lynch syndrome is a genetic (inherited) condition and is the most common cause of hereditary colon cancer. Lynch syndrome increases the risk of colorectal cancer, endometrial cancer, and several other types of cancer, including stomach, small intestine, liver, kidney, gallbladder, urinary tract, brain, skin, and ovarian cancer. 

Lynch syndrome is the most common genetic condition that can increase the risk of these cancers. Lynch syndrome causes about 4,200 colorectal cancers and 1,800 endometrial cancers every year. 

In addition to an increased risk of cancer, Lynch syndrome can cause cancer to develop at an earlier age (before age 50) than people who do not have Lynch syndrome. 

You may also hear Lynch syndrome referred to as

• Cancer family syndrome
• Familial nonpolyposis colon cancer
• Hereditary nonpolyposis colorectal cancer
• Hereditary nonpolyposis colorectal neoplasms
• HNPCC

Novalab Reference Medical Lab offers genetic counseling after the testing. 

What causes Lynch syndrome?

Lynch syndrome is usually inherited in an autosomal dominant way—meaning if one parent has a gene mutation for Lynch syndrome, then there is a 50% chance that each child will inherit the mutation and have a higher risk for cancers. 

In rare cases, a person can inherit a mutation that their parents do not have. This type of inheritance means that the mutation happened before the person was conceived or born. A person who inherits a gene mutation for HCC still has a 50% chance of passing the gene to each child. 

Another, even less common way for HCC to be inherited is called autosomal recessive. This means both copies of a gene must have a mutation to increase the risk for cancer. Usually, this means the person inherited one mutation from each parent. The parents each have another normal copy of the gene and do not have symptoms. These parents have a 25% risk of passing the gene on with each pregnancy. 

How do gene mutations cause cancer?

When cells in the body grow and divide, they copy DNA. Sometimes, small mistakes occur during the process. Normal cells realize there is a mistake, and can fix the mistake. But in people with Lynch syndrome, the cells cannot fix these small mistakes. When a number of small mistakes occur, eventually the cells can become cancerous. 

Should I get tested for Lynch syndrome?

Ask your doctor or genetic counselor about testing for Lynch syndrome. Generally, the following people should be tested:

• People who are newly diagnosed with colorectal or endometrial cancer.
• People who have more than one cancer related to Lynch syndrome. These cancers include colorectal, endometrial, ovarian, gastric, small bowel, upper urinary tract, hepatobiliary tract, pancreas, brain, and sebaceous neoplasia of the skin.
• People with a family history of colorectal or endometrial cancer – those with 2 or more relatives with one of these cancers, especially if cancer occurred before age 50 years. 

Our genetic counselors can meet with you and help you determine if you need genetic testing for Lynch syndrome and other cancers. The testing is simple, and only requires a swab and one tube of blood.

Genetic testing results and what they mean

Genetic testing will look for changes in genes that show you have Lynch syndrome. These genes include:

• MLH1
• MSH2
• MSH6
• PMS2
• EPCAM

The following table shows Lynch syndrome test results and their meaning.