Your Genetics

Does colorectal cancer run in your family?  If so, we can help protect your future…

Most colon cancer happens by chance. However, 5-10 % of all colon cancer is caused by a single hereditary gene and can be associated with other concerns like endometrial (lining of the uterus)and ovarian cancer.  Hereditary cancer is often diagnosed at younger ages, before screening for colon cancer is normally offered.  If you or someone in your family has early colorectal cancer, educating yourself about your family history and checking for the presence of a hereditary cancer gene could save your life.

When a hereditary cancer gene is present, the family history often includes one or more of the following:

  • Colon cancer diagnosed before 50 years of age
  • Multiple colon cancers in the same individual
  • Endometrial cancer
  • Colon and endometrial cancer in the same individual
  • Other less common cancers ie. stomach, ovarian, urinary tract, bile duct, brain
  • Multiple polyps (> 15 ) in the same individual

More well-known hereditary colon cancer syndromes are listed below:

Hereditary Nonpolyposis Colorectal Cancer (HNPCC)

This condition is inherited as a dominant trait in the family and can increase the risk for colon cancer to as high as 80%.  The chance for endometrial cancer is also high, up to 60% in women who carry a broken gene for this condition.  The good news is that cancer can usually be prevented by doing colonoscopy more frequently and at much younger ages in individuals who have a gene change identified on genetic testing.  Endometrial cancer can be prevented by having a hysterectomy once child-bearing is completed.

Familial Adenomatous Polyposis (FAP)

This rare condition leads to colon cancer at very young ages because large numbers (thousands) of polyps begin to form in the colon starting in the teen years.  The average age of colon cancer diagnosis is 34.  First degree relatives have a 50/50 chance of inheriting the same condition and, if identified, a colectomy (removal of the colon) is the best prevention once polyps begin to form.  Individuals who carry a gene for FAP will develop colon cancer if preventative efforts are not pursued.

Attenuated Familial Adenomatous Polyposis (AFAP)

If several polyps are found in an individual, but there are less than 100, a diagnosis of AFAP is possible.  In this dominant condition, the risk for colon cancer is up to 100% but is diagnosed at older ages than FAP.  More frequent and early colonoscopy can prevent cancer and save lives.

Genetic testing for these conditions usually involves a simple blood draw.  A tumor sample can be required in some cases.  Results take about 3-6 weeks.  Insurance coverage can be verified before testing. 

Early detection is critical to preventing and treating colorectal cancer.  Genetic testing can help identify individuals who need earlier and more frequent colonoscopy to save lives.  There may also be a need to screen for other types of cancer.  If you have a strong family history of colorectal and/or other cancers, discuss the opportunity for hereditary cancer risk assessment and genetic counseling with your doctor.  It could make a significant difference in your future health and the health of your family.

Debbie Pencarinha, MS, CGC
Genetic Counselor
Kingsport Hematology and Oncology Associates