Hereditary Colon Cancer
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.
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.
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, Crohn’s disease
- Diets high in fat and/or low in fiber
- Smoking/tobacco use
- Physical inactivity and/or obesity
- Type 2 diabetes