Genetics and family history often play a large role in one's health. People affected by Lynch syndrome, an inherited tendency to develop certain cancers, know this all too well.
Answering questions about Lynch syndrome is Karen Lu, M.D., professor in Gynecologic Oncology.
What is Lynch syndrome?
Lynch syndrome is an inherited cancer predisposition syndrome. Also called hereditary nonpolyposis colorectal cancer syndrome (HNPCC), Lynch syndrome greatly increases the risk of colorectal and endometrial cancers. There also is a smaller risk for cancers of the small bowel, urethra and ovary.
What are the cancer risks for people with Lynch syndrome?
Men with Lynch syndrome have a 60% to 80% lifetime risk of developing colon cancer. Women have a 40% to 60% lifetime risk of developing colon cancer, as well as a 40% to 60% chance of developing endometrial cancer. The risk of developing cancers of the small bowel, urethra and ovary are each between 5% and 10%.
What causes Lynch syndrome?
Lynch syndrome is caused by a mutation in the MLH1, MSH2, MSH6 or PMS2 gene. These genes are responsible for repairing mistakes in DNA. Therefore, if one of these genes is mutated and stops working, a person is more susceptible to these cancers, particularly at a young age.
Because Lynch syndrome is hereditary, there is a 50% chance that a person will pass on the mutation to each of his or her children. Lynch syndrome does not skip generations. Males and females are equally likely to be affected.
In the general population, the prevalence of Lynch syndrome is between 1-in-500 and 1-in-1,000.
What should people do if they think Lynch syndrome is in their family?
The first step is for patients to talk to their doctors. From there, they can see a genetic counselor who will draw out their family tree and look for patterns of inherited cancer. The red flags we typically look for are multiple family members with colon or endometrial cancer, any family members who had both colon and endometrial cancers, or any family members who had an early onset of cancer and were diagnosed before age 50.
How is Lynch syndrome diagnosed?
It generally begins when we see someone with cancer, usually in the gynecologic oncology or gastrointestinal center. If we see that his or her family medical history looks suspicious, or if he or she has been diagnosed at a young age, we closely examine to see if that patient might have Lynch syndrome. We then do some tumor studies to give us a clue as to whether or not our original assessment was correct. If those studies end up looking suspicious, we recommend genetic testing for the patient.
How do you manage Lynch syndrome?
Consensus groups recommend that people with Lynch syndrome get a colonoscopy every one to two years. This decreases the mortality rate due to colon cancers.
There are less data to support screening for endometrial or ovarian cancers. Currently, we recommend that people with Lynch syndrome get an endometrial biopsy every one to two years to screen for endometrial cancer. We also recommend that they get an ovarian ultrasound.
Another option for female patients with Lynch syndrome is to undergo a prophylactic hysterectomy and to remove the ovaries when childbearing is complete. This precaution will decrease the risk of developing endometrial and ovarian cancer.
What is your advice for patients who have Lynch syndrome?
Patients who have a strong family history of cancer should learn more about Lynch syndrome. They should talk to their doctor to see if genetic counseling and testing would benefit them.
For patients who already know they have Lynch syndrome, we recommend they undergo the necessary screenings.