Genetics makes some families more prone to developing some cancers. But if families know that they have Lynch syndrome, they should start getting tested for cancer early, says Emily Kuchinsky, MS, a certified genetic counselor at Baltimore MedStar Health Cancer Network.
What is Lynch syndrome? Lynch syndrome is the most common cause of inherited colon and endometrial cancer [cancer in the lining of the uterus]; about 2 to 3 percent of colon and endometrial cancer is associated with Lynch syndrome. Lynch syndrome increases risk for endometrial and other cancers up to ten times over the general population risk. A person with Lynch syndrome is also at risk for developing cancer at earlier ages than normal and developing multiple primary cancers.
What causes Lynch syndrome? Lynch syndrome is caused by inherited DNA alterations in at least five genes. Genes are the blueprints for the body and instruct cells to grow, develop and function normally. When there is an alteration within a gene, the function of that gene is impaired or halted. The Lynch syndrome genes, when functional, ensure the repair of DNA mistakes during cell division, so an altered Lynch syndrome gene causes cells to acquire more mistakes, which lead to the development of cancer.
Every person has two copies of each gene, including the Lynch syndrome genes. When a parent has Lynch syndrome, or carries a genetic alteration in one of their Lynch syndrome genes, there is a 50 percent chance that each of their children will inherit the altered gene and also have Lynch syndrome.
What family histories suggest Lynch syndrome? Family histories suggestive of Lynch syndrome include having three or more family members (on the same side of the family) with colon, endometrial, ovarian or gastric cancers, especially if the family members were diagnosed with cancer at age 60 or younger. However, family histories can also be deceiving. Smaller family sizes, increased uptake of colonoscopies and women who underwent hysterectomies may decrease the amount of cancer present in a Lynch family. Even having one relative with an early-onset colon cancer, diagnosed at age 50 or below, is enough to consider [meeting with a genetic counselor].
What are the cancer risks associated with the disease? A person with Lynch syndrome has up to an 80 percent lifetime risk for colon cancer and up to a 60 percent chance for endometrial cancer. There are also moderately increased risks for gastric cancer, a 6 percent lifetime risk, and up to a 12 percent lifetime risk for ovarian cancer. There are slightly increased risks, up to 4 percent, for small bowel, brain, urinary, hepatobiliary tract [liver, bile ducts and gallbladder] and sebaceous gland tumors.
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How is it diagnosed? Lynch syndrome is typically first diagnosed by performing a staining test on tissue from colon or endometrial cancer. If this tumor test is abnormal, then the patient will be requested to follow up with a genetic counselor, who will offer blood testing to confirm the presence of genetic alterations consistent with Lynch syndrome.
If no one in the family with cancer is living, then relatives with a suspicious family history for Lynch syndrome should meet with a genetic counselor to discuss the option of directly proceeding with genetic testing.
Why is it important to make sure it is diagnosed early? In the general population, screening for colon cancer is not recommended until the age of 50, over the age at which most colon cancers associated with Lynch syndrome develop. Testing of relatives in a family known to have Lynch syndrome should be performed by the age of 20 because if relatives are positive for the genetic alteration, they can begin colonoscopies at age 20 to 25.
How is it managed? The medical management recommendations for Lynch syndrome include: colonoscopies every one to two years beginning at age 20 to 25, and upper endoscopy every three to five years beginning at age 30 to 35. For women, consider screening for endometrial and ovarian cancers beginning at age 30, and women should strongly consider a prophylactic hysterectomy with bilateral oophorectomy, or the removal of ovaries, once child bearing is complete. For men and women, consider urinalysis beginning at age 25 to 30, and an annual physical exam and neurological exam starting at 25 to 30.
For individuals who are compliant with these guidelines, there is significant reduction of cancer incidence and over a 60 percent reduction in mortality.