Approximately 5 to 10 percent of colon cancer
is hereditary. The major hereditary colon cancer syndromes are Lynch syndrome
(previously known as Hereditary Non-Polyposis Colorectal Cancer or HNPCC) and
Familial Adenomatous Polyposis (FAP). Other genes have also been implicated in
hereditary colon cancer risk.
The genetic risk assessment service at UT Southwestern Simmons
Comprehensive Cancer Center offers testing and genetic counseling for colon
cancer and all other identified cancers. Based on an individual’s personal and
family history of cancer, our genetic counselors can identify the level of
risk, determine if genetic testing is appropriate, and provide guidance for an
early detection and prevention strategy.
Watch a video about hereditary colon cancer management.
Colon Cancer Facts
One in 18 individuals (5.5 percent) will
develop colon cancer in their lifetime. Of all colon cancer cases, only about 5
to 10 percent are hereditary, linked to gene mutations inherited from one’s
mother or father.
Multiple genes are associated with
hereditary colon cancer, but mutations in genes associated with Lynch syndrome
(MLH1, MSH2, MSH6, PMS2, EPCAM) are the most common cause of the hereditary
form of the disease. Prediction models can estimate
an individual’s risk for a Lynch syndrome mutation.
Additional information on colon cancer
predisposition genes can be found on the Hereditary Colon Cancer
Gene List listed below.
Approximately 25 to 35 percent of colon
cancer is familial, meaning the disease occurs more often in family members
than can be expected in the general population even though a particular gene
mutation has not been identified in the family. With familial colon cancer, the
specific cause of colon cancer is unknown but likely due to combinations of
risk factors including genetics, lifestyle, and environment that increase risk
in the family.
Screening recommendations vary for individuals with an
increased lifetime risk for colon cancer based on a hereditary cancer
syndrome or family history.
The remainder of colon cancer diagnoses
(around 70 percent) are considered random or sporadic and non-hereditary,
without a known etiology. Risk factors for sporadic colon cancer include:
- Age (9 out of 10 people are over age 50)
- Inflammatory bowel disease, ulcerative colitis,
- Diets high in fat and/or low in fiber
- Smoking/tobacco use
- Physical inactivity and/or obesity
- Type 2 diabetes