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The State of the Fight: Lynch Syndrome

by Stephen B. Gruber, M.D., Ph.D., M.P.H.

The State of the Fight: Lynch Syndrome
Stephen B. Gruber, M.D., Ph.D., M.P.H., is director of the USC Norris Comprehensive Cancer Center at the University of Southern California.

Lynch Syndrome is a common genetic disorder that places a person at greater risk for colon cancer and endometrial cancer. It is estimated that one in 440 Americans carry a mutation that causes Lynch Syndrome.

Lynch Syndrome is caused by mutations in genes that repair DNA. The genes that cause Lynch Syndrome are passed from parent to child, and a child of a parent with Lynch Syndrome has a 50 percent chance of having the gene that causes the disorder.

Approximately 2 percent to 4 percent of all diagnosed colorectal cancers and 2 percent to 5 percent of all diagnosed endometrial cancers are due to Lynch Syndrome. Despite the fact that Lynch Syndrome is common, not all people who carry the gene go on to develop cancer: genetics is not destiny.

The good news is that many people with Lynch Syndrome lead healthy lives. Colonoscopy can reduce the risk of colorectal cancer by 65 percent and has been unequivocally shown to save lives. To reduce endometrial cancer risk with Lynch Syndrome, oral contraceptives are highly recommended for women not actively seeking pregnancy. After menopause, removing the uterus and ovaries completely eliminates the risk of uterine cancer and dramatically reduces the risk of ovarian cancer.

Information about Lynch Syndrome has developed tremendously over the past 20 years. Not only do we now know what causes Lynch Syndrome, we know cost-effective ways to diagnose and care for patients with Lynch Syndrome. Research in my lab today is focused on understanding the risk of cancer in gene carriers and how to prevent and treat cancer in those with the gene. Together with our collaborators across the United States, we have shown that genetic testing is cost-effective in a number of different settings, and shown that screening and treatment unequivocally save lives.

There are no specific symptoms or warning signs of Lynch Syndrome. This is one of the many reasons doctors offer genetic testing to healthy people who are at-risk based on their family history alone. Otherwise, prevention is the key to treating Lynch Syndrome, and it is clear that using strategies that include routine colonoscopies, oral contraceptives, and preventative surgery are often effective. However, given that no type of prevention is perfect, it is important to also be aware that if cancer does arise, treatment can be tailored for a patient with Lynch Syndrome.

Lynch Syndrome is diagnosed in several ways, and the most common method is by recognizing the classic patterns of cancer within a family. The rule of thumb that helps people recognize Lynch Syndrome is the “3-2-1-0 rule.” This pattern represents three people in a family with either colon or uterine cancer, in two or more generations, with one person diagnosed below the age of 50. The “zero” represents the designation that a rare condition called familial polyposis, characterized by hundreds or thousands of polyps that carpet the colon, has been excluded.

The second way to recognize Lynch Syndrome is by special stains and tests that can be performed on tumor tissue. Pathologists are very good at recognizing the features of Lynch Syndrome, and now there are tests that show whether cancers have the hallmark features of Lynch Syndrome. These pathology results can lead physicians to order additional diagnostic tests to confirm the diagnosis.

Ultimately, Lynch Syndrome is diagnosed on the basis of a gene test. When a mutation is identified in one of the four mismatch repair genes that cause Lynch Syndrome, a diagnosis is confirmed. Genetic testing for Lynch Syndrome is now the standard of care for patients and families with the mutation.

Children of individuals with Lynch Syndrome are at highest risk; it is quite rare for a new mutation to arise spontaneously. Unfortunately, Lynch Syndrome is under-recognized. Even some patients with colon cancer or uterine cancer are unaware that their cancer may have arisen on the basis of Lynch Syndrome. The best way to be sure about your own risk for Lynch Syndrome is to know your family history and ask your doctor.

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In America more than 1.2 million new patients are diagnosed with cancer every year. A new cancer is diagnosed every 30 seconds in the United States.