Recommendations and genetic counseling for carriers of Lynch syndrome, a cause of hereditary colorectal cancer

Genetic counseling is frequently mentioned in cancer but not widely understood. Because cancer is a genetic disease at the cellular level, all efforts to understand and treat it draw on genetics. However, genetic counseling currently has a more limited application in cancer. These areas can be classified under three headings:

1. Tests identifying particular tumor characteristics and suitability for targeted drugs, such as KRAS testing in colorectal cancer and Her2 testing in breast cancer
2. Genetic tests, such as detecting mutations in genes causing Lynch syndrome
3. Establishing a family tree, identifying people at risk and managing their care

I am a Lynch syndrome (LS) carrier; what should I do?

If you carry mutations in the 5 Lynch-syndrome-associated genes (MLH1, MSH2, MSH6, PMS2 and EPCAM), recommended cancer screening is as follows:

For colon cancer:

• Colonoscopy starting at age 20-25 or 1 year before the earliest family diagnosis of colon cancer, repeated every 1-2 years
• Studies suggest that aspirin use in people with LS reduces the risk of future cancer. However, discuss the daily dose and whether it is suitable for you with your physician

For uterine and ovarian cancer:

• If no future children are planned, preventive hysterectomy and bilateral salpingo-oophorectomy (surgical removal of the uterus and ovaries) may be considered to reduce risk
• Patients should know that bleeding outside menstruation requires physician assessment
• An annual general gynecological examination is recommended

For stomach and small intestine cancer:

Although clear evidence supporting endoscopic stomach cancer screening is lacking, LS carriers, particularly those with a family history of stomach cancer, are recommended to undergo esophagogastroduodenoscopy every 3-5 years, examining the esophagus, stomach and duodenum with an instrument bearing a lighted camera.

• For urinary tract cancer: Annual urinalysis from age 30-35.
• For central nervous system (CNS) cancer: Annual neurological examination from age 25-30.
• For breast cancer: Breast cancer risk is known to be increased in LS carriers.

Although there are no clear recommendations to bring forward routine annual mammography, which begins for women at age 45, annual mammography and breast ultrasound from the 30s may be suggested. In LS carriers, a form of genetic instability called microsatellite instability matters for risk calculation, prognosis prediction and treatment selection. Another article discusses the importance of microsatellite instability for LS.

Related topic: Lynch syndrome—a brief story of the father of cancer genetics