10 Facts About the 'Cancer Family Syndrome'by Rachel Zohn Health Writer
Lynch syndrome, also known as hereditary non-polyposis colorectal cancer (HNPCC) or the "cancer family syndrome," is a type of inherited cancer disorder. People with Lynch syndrome have a genetic predisposition and higher risk of developing colon and other types of cancers. Families with Lynch syndrome usually have multiple members who have been diagnosed with cancer. People with this condition are more likely to be diagnosed at a younger age and are at risk for contracting multiple types of cancer.
Lynch syndrome and cancer
People with Lynch syndrome have a higher lifetime risk of developing cancer and an increased risk of getting more than one of the cancers link to the condition. These include cancers of the colon and rectum, but also a number of others such as stomach, small intestine, liver, gallbladder ducts, urinary tract, brain, pancreatic, prostate, and skin. Women also have an increased risk of developing endometrial and ovarian cancers.
History of ‘cancer family syndrome’
Henry Lynch, MD, for whom Lynch syndrome is named, is regarded as one of the fathers of cancer genetics for his groundbreaking work on hereditary cancers in the 1960s and 1970s. He studied a number of families in the Midwest with higher than normal incidence of cancers, particularly colon cancer, coining the term “cancer family syndrome.” Lynch was noted for using statistics to identify the genetic nature of a family’s predisposition to cancer.
It’s in the genes
Cancer begins when normal cells change and grow out of control, forming a mass called a tumor. People with Lynch syndrome have mutations in one of several genes involving the mismatch repair (MMR) system. The genes that that are linked to Lynch syndrome include MLH1, MSH2, MSH6, PMS2, and EPCAM. A mutation in any of these genes gives a person an increased lifetime risk of developing Lynch syndrome-related cancers.
Mutation in DNA mismatch repair genes
Lynch syndrome is caused by a mutation in MMR genes, which work to repair mistakes made when DNA is copied as part of cell division, much like a spell checker catches typos on a computer. These gene defects allow DNA mistakes to remain, unchecked. As cells divide, these errors stack up and uncontrollable cell growth may result in tumors and cancer.
A genetic, generational condition
Lynch syndrome is a genetic condition passed from parent to child. Families that have Lynch syndrome usually have more cases of colon cancer than normal and are often diagnosed with colon cancer at a younger age (before 50) than the general population. The condition follows an autosomal dominant inheritance pattern, with one inherited copy of the altered gene in each cell sufficient to increase cancer risk. However, not everyone who inherits a mutation in these genes will develop cancer.
Other types of linked hereditary syndromes
Muir-Torre syndrome and Turcot syndrome are hereditary conditions that are associated with Lynch syndrome. People with Muir-Torre syndrome often develop rare skin lesions and are at risk for developing cancers often seen with Lynch. People with Turcot syndrome often develop multiple colon polyps and have an increased risk of colorectal cancer and brain cancer.
How common is Lynch syndrome?
Lynch syndrome is the most common hereditary cause of colorectal cancer and endometrial cancer in women. It accounts for between 2-4 percent of all colorectal cancers and 2-5 percent of endometrial cancers in women. However, someone with Lynch syndrome has a 40-80 percent lifetime chance of getting colorectal cancer. Women with the condition have a 20-60 percent chance of getting endometrial cancer.
Red flags to be aware of
Some criteria that may be red flags for Lynch syndrome:
- Developing colon cancer younger than 50
- Developing colon cancer along with other types of cancer that are linked with Lynch syndrome.
- Colon cancer in one or more first degree relatives (parents, siblings, children) who also had another Lynch syndrome-related cancer.
- Colon cancer in 2 or more second degree relatives (aunts, uncles, grandparents, grandchildren, nephews, and nieces) who also had another related cancer.
What you can do?
If a close family member had colorectal cancer at a young age or multiple close family members have been diagnosed with colorectal cancer, consider asking your doctor if you should begin screening for colon cancer earlier than normal and if you should be screened more frequently. You may also consider having genetic screening and counseling.
A genetic test from blood or saliva can determine if you carry the mutation for Lynch syndrome. For those diagnosed with cancer, an immunohistochemistry test (IHC) may be used to determine if a tumor is caused by Lynch syndrome. Once Lynch syndrome has been discovered in a family member, other relatives can be tested for the mutation to find out if they also have it. If positive, there is a 50 percent chance that parents, children, and siblings will also have this condition.
Recommended screenings for Lynch syndrome
The American Society of Clinical Oncology (ASCO) recommends that people with Lynch syndrome get a colonoscopy every one to two years starting between 20 and 25 years, or five years younger than the earliest diagnoses of a family member, whichever is sooner. Women with Lynch syndrome should consider screenings of their ovaries and uterus with transvaginal ultrasounds and endometrial biopsies.