Lynch syndrome is a type of genetic condition that increases a person’s likelihood of developing cancers along the digestive or gynecological tract, as well as other areas of the body.
The condition was formerly known as “hereditary nonpolyposis colorectal cancer” (HNPCC) before its relationship to other types of cancers was better determined. Lynch syndrome is the result of defects in the body’s DNA mismatch repair systems. These are key mechanisms that mend certain types of genetic damage and respond to any flaws that arise from DNA replication.
Unfortunately, the faults in the repair systems can put you at a higher risk of developing tumors at an earlier age.
Causes of Lynch Syndrome
Your cells regularly create new DNA, and this new genetic material is regularly flawed. Genes can be out of place or missing, extra ones can be present, and a number of other forms of damage are possible. The mismatch repair system is what corrects these errors to maintain the DNA’s integrity and to keep genes working as they are supposed to. When mutations cause this process to falter, the result can be Lynch syndrome.
Most mutations associated with Lynch syndrome are found in the MLH1 or MSH2 genes. Some families with Lynch syndrome also have associated mutation in the MSH6, PMS2, and EPCAM genes, but this is not always the case. Lynch syndrome can sometimes arise spontaneously as a person ages and their genes develop more flaws. It is, however, more likely to be from inheritance.
Lynch syndrome has two variants, Muir-Torre syndrome and Turcot syndrome, which specify which parts of the body are more at risk. Muir-Torre makes you more vulnerable to uterine, stomach, ovarian, intestinal, urinary tract, prostate, and liver or bile duct cancers. Turcot syndrome is connected to colorectal and brain cancers.
Signs and Symptoms of Lynch Syndrome
The term “syndrome” refers to a collection of symptoms that appear together without an identifiable pathogen or similar cause being present. A syndrome is diagnosed by observing a patient’s condition and history to see if they meet certain criteria. For Lynch syndrome, the following criteria are used in diagnoses:
- Developing colorectal cancer before age 50.
- Developing colorectal cancer along with another Lynch syndrome-linked cancer.
- Developing colorectal cancer where the tumor shows Lynch syndrome-related defects.
- A parent or sibling who has developed colorectal cancer and another Lynch syndrome-related cancer. At least one cancer must develop before age 50.
- Two or more relatives (up to two degrees away) who develop colorectal and another Lynch-related cancer.
Additionally, Muir-Terre and Turcot syndrome have separate identifying symptoms that can aid in diagnoses. Individuals with Muir-Terre are at an increased risk of developing noncancerous lumps or cysts on or under the skin. Turcot syndrome often results in the development of polyps, a type of growth that forms on mucus membranes and can sometimes become cancerous.
As those with Lynch syndrome are at the highest risk of getting colorectal cancer (about 80% of those with the syndrome develop it) standard guidelines are to test all colon tumors for the abnormalities associated with Lynch syndrome. If they are found, the patient’s blood is tested to see if the genetic defects are present.
Lynch Syndrome and Breast Cancer
You may have noticed that breast cancer was not listed above when discussing what Lynch syndrome makes you more vulnerable to. This is because the link between breast cancer and Lynch syndrome is not as fully understood or identified as the other types. What is understood is that an increased level of risk does exist in some form, and seems to be related to mutations in the MMR gene. Whether these mutations are frequent enough to be considered part of the Lynch syndrome “package” remains to be seen.
What studies exist on the subject indicate that women with Lynch syndrome are about four times more likely to develop breast cancer. However, this is not a definitive statement. The body of research on Lynch syndrome and breast cancer is still developing, and breast cancer is also relatively common in general. It is possible that, as a more comprehensive investigation is done, the increased risk will be better stated or dismissed.
Lynch Syndrome and Pancreatic Cancer
The connection between Lynch syndrome and pancreatic cancer is a little more defined than that with breast cancer, but it is still an ongoing discussion. What is known is that research comparing 147 families (6,342 people total) with Lynch syndrome to those without found that around 20% of Lynch syndrome families (31 families) experienced at least one case of pancreatic cancer, with 47 reported cancers overall and no significant gender differences. This results in an approximate 3.7% chance of developing pancreatic cancer. This may not seem high, but it is 8.6 times higher than the general populace.
Lynch syndrome is best identified early so that you can start regular screening. Lynch syndrome has about a 50% chance of being inherited if only one parent has the gene. If you don’t know if your family has a history of Lynch syndrome, check if any relatives have had colon cancer or multiple types of cancer. Should this be the case, ask if a Lynch syndrome test was done. Alternatively, you can simply get tested yourself directly.
Since Lynch syndrome is most commonly linked to colon cancer, colonoscopies are urged every one to two years starting at either the age of 20, or five years younger than the earliest diagnoses in your family, whichever is earliest. Your family history, personal medical history, and your doctor’s evaluation will establish what other cancers you should be screened for. As always, be sure to consult with your doctor first about any concerns or suspicions you have.
Sources for Today’s Article:
Kastrinos, F., “Risk of Pancreatic Cancer in Families With Lynch Syndrome,” Journal of the American Medical Association, 2009; 1790-795, doi:10.1001/jama.2009.1529.
“Lynch Syndrome,” Cancer.net, http://www.cancer.net/cancer-types/lynch-syndrome, last accessed October 29, 2015.
“Lynch Syndrome Also Linked with Breast and Pancreatic Cancer,” Susan G. Komen web site, February 20, 2012; http://ww5.komen.org/Breast-Cancer-News/Lynch-Syndrome-Also-Linked-with-Breast-and-Pancreatic-Cancer.html.
“Lynch Syndrome,” Canadian Cancer Society web site, http://www.cancer.ca/en/cancer-information/cancer-101/what-is-a-risk-factor/genetic-risk/lynch-syndrome/?region=on, last accessed October 29, 2015.
“Muir-Torre Syndrome,” Cancer.net, http://www.cancer.net/cancer-types/muir-torre-syndrome, last accessed October 29, 2015.
“Turcot Syndrome,” Cancer.net, http://www.cancer.net/cancer-types/turcot-syndrome, last accessed October 29, 2015.
Win, A., et al., “Risk of Breast Cancer in Lynch Syndrome: A Systematic Review,” Breast Cancer Research, 2013; doi: 10.1186/bcr3405.