Lynch Syndrome, Explained
What is Lynch Syndrome?
Lynch syndrome is a genetically inherited condition, also known as hereditary nonpolyposis colorectal cancer (HNPCC)¹. Lynch syndrome increases the risk of a number of cancers, including cancer of the colon, ovary and uterus, stomach, pancreas, urinary tract and prostate¹. Although there are many genetic syndromes which cause an increased risk for colorectal cancer, Lynch syndrome is the most common¹. It is estimated that about 1 in every 300 people carry an altered gene associated with Lynch syndrome¹, and approximately 3 in 100 colorectal cancer cases can be associated with Lynch syndrome². Lynch syndrome is especially important for early-onset colorectal cancer patients, or those at risk of early-onset colorectal cancer, because it is a prominent risk factor.
How do you know if you have Lynch syndrome?
If one side of your family has high instances of colon and endometrial cancer, especially at an early age onset, it is possible that some of your family members could have Lynch syndrome. The Bethesda guidelines outline the criteria which help guide who should be tested for Lynch syndrome:
● Developing colorectal or endometrial cancer younger than age 50¹
● Developing colorectal cancer, endometrial cancer, or other type of cancer* with mismatch repair deficiency (MMR-D) or high-level microsatellite instability (MSI-H) found on testing of the tumor specimen¹
● Developing colorectal cancer and other types of cancer* linked with Lynch syndrome separately or at the same time¹
● Colorectal cancer in 1 or more first-degree relatives who also has or has had another Lynch syndrome-related cancer*, with 1 of these cancers developing before age 50. The phrase “first-degree relatives” include parents, siblings, and children.¹
● Colorectal cancer in 2 or more first- or second-degree relatives with another Lynch syndrome-related cancer*. “Second-degree relatives” include aunts, uncles, grandparents, grandchildren, nephews, and nieces.¹
*category includes colorectal cancer, endometrial cancer, ovarian cancer, stomach cancer, small bowel cancer, ureter or renal pelvis cancer, bladder cancer, bile duct cancer, pancreatic cancer, or sebaceous adenomas of the skin¹
I have Lynch Syndrome, now what?
If you have or are at risk for Lynch syndrome, an important first step is to discuss a screening and risk-reduction plan with your healthcare provider. For those with a family history of Lynch syndrome, screening practices should begin much earlier than the general population. This could help detect cancers at an earlier stage to improve outcomes.
Another important factor to consider is fertility and passing on the Lynch syndrome gene to your offspring. A child who has a parent with Lynch syndrome has a 50% chance of inheriting the mutation themselves¹. Through preimplantation genetic diagnosis (PGD) and in-vitro fertilization (IVF), it is possible for reduce the risk that their children will inherit the mutation¹. This process includes the fertilization of a woman’s egg in a laboratory, and genetic testing being done on an embryo to determine the status of the hereditary mutation. However, this process includes financial, physical and emotional strain which must be discussed among the family prior¹.
Research also shows that young survivors of colorectal cancer can have decreased fertility, especially in young women³. If you have concerns about fertility in the future, speak to an assisted reproduction specialist to discuss the possibilities of freezing eggs or sperm, and the possibility of IVF in the future.
Learn more about Colorectal Cancer Canada’s Never Too Young Program.
²https://www.mayoclinic.org/diseases-conditions/lynch-syndrome/symptoms-causes/syc-20374714
