You may inherit your mother's blue eyes or your father's temperament, but you cannot technically inherit colon cancer. What you can inherit are the genes that predispose you to colon cancer by increasing your risk of developing the disease.
Although you cannot control the genes that you inherit, you can control your lifestyle risk factors and how often you get screened for colon cancer.
There are different types of familial medical histories that may increase your risk of developing colon cancer. The three family histories to watch out for include:
According to the American Cancer Society, 20 percent of people diagnosed with colon cancer also have a family history of the disease.
First-Degree RelativesIf one of your immediate family members (mother, sister, child) has been diagnosed with colon cancer, your risk of developing the disease increases. Immediate family members are more accurately defined as first-degree relatives, which include your parents, siblings or children. Your risk of developing colon cancer increases by three to six times that of the average individual if you have multiple first-degree relatives with colon cancer or one first-degree relative who was diagnosed before they were 60.
Family History of CancerA family history of cancer, especially adenomas, can increase your personal risk of developing colon cancer. Cancers most commonly associated with colon cancer include uterine, ovarian and stomach cancer. People with a history of breast cancer have a slightly elevated risk of developing colon cancer.
Familial Adenomatous Polyposis SyndromeFamilial adenomatous polyposis syndrome (FAP) is a genetic disorder that predisposes you to colon cancer. FAP is diagnosed through genetic testing and will, in most cases, lead to colorectal cancer if you do not get treatment.
This syndrome causes your body to create thousands of adenomatous polyps in your colon, starting in adolescence. One of 10,000 babies will be born with FAP. If you suspect a family history of this syndrome, talk to your doctor about genetic testing and counseling.
If you or a first-degree relative has been diagnosed with FAP or if there is a family history of the syndrome, you are in the high-risk category for colon cancer screening. Colon cancer screening should start between the ages of 10 and 12, with an annual flexible sigmoidoscopy to follow. Your doctor may talk to you about bowel surgery to remove the colon, which is called a colectomy. The colectomy procedure is the foremost treatment modality for FAP.
Hereditary Nonpolyposis Colorectal Cancer SyndromeHereditary nonpolyposis colorectal cancer syndrome (HNPCC) is also known as Lynch syndrome. Not only does HNPCC increase your risk of developing colon cancer, it also increases your risk of developing uterine (women), stomach, bile duct and urinary tract cancers. Unlike FAP, HNPCC does not stimulate thousands of adenomas in your colon, but it does facilitate polyp growth. People with HNPCC may also have aggressive tumors, which can grow and spread faster than average.
People with HNPCC should begin screening by the time they are 20 to 25. If a first-degree relative has been diagnosed with colon cancer, you should begin screening 10 years prior to the age they were diagnosed (or at 20 to 25 years old, whichever comes first). A colonoscopy every one to two years may follow the initial screening.
Rare Genetic Mutations
- Peutz-Jeghers syndrome is a very rare genetic syndrome that is characterized by special polyps in the gastrointestinal tract and may be accompanied by freckles around the mouth, hands and feet. Peutz-Jeghers syndrome greatly increases your chances of developing colon cancer. It is caused by a defect in the STK1 gene and can be diagnosed through genetic testing.
- Juvenile polyposis is a condition that causes multiplication of the polyps in the gastrointestinal tract of young children. It will lead to colorectal cancer if untreated.
- Turcot syndrome is another very rare syndrome that can increase your risk of developing adenomatous polyps. There are two variations of Turcot - one that mimics FAP and one that mimics the mutations seen in HNPCC. Turcot syndrome may also increase your risk of developing brain cancer.
- MUTYH associated polyposis is a syndrome that causes cancerous colon polyps and increases your risk of other cancers.
Genetic TestingGenetic testing is used to detect the gene mutations that radically increase your chances of getting colon cancer, such as in FAP or HNPCC. Genetic testing requires a well-documented family history of cancer or related syndrome (for insurance coverage), a blood sample and a genetic counselor to walk you through the results and possible ramifications.
The American Cancer Society strongly encourages genetic testing for people who have a proven case of FAP or HNPCC in a first-degree relative. You may also want to consider genetic testing if you have a strong family history of inflammatory bowel diseases, such as ulcerative colitis or Crohn’s disease.
American Cancer Society. (2006). American Cancer Society’s Complete Guide to Colorectal Cancer. Clifton Fields, NE: American Cancer Society.
American Cancer Society. (n.d.). American Cancer Society Guidelines for the Early Detection of Cancer. Accessed February 20, 2012.
American Cancer Society. (n.d.). Can Colorectal Cancer and Polyps Be Found Early? Accessed February 22, 2012.
American Cancer Society. (n.d.). Risk Factors for Colorectal Cancer. Accessed February 12, 2012.
Rex, D.K., Liangpunsakul, S. (April 2007). Colorectal Cancer Screening. American College of Gastroenterology. Accessed February 21, 2012.