Genetics and Cancer - The Genetics of Colorectal Cancer
Approximately 25 percent of individuals with colorectal cancer have at least one relative with colorectal cancer, while 75 percent of cases are persons without a family history of the disease. Approximately 5 percent of colorectal cancers are due to known predisposing genetic factors. This means that the majority of colorectal cancers are, in fact, not inherited. Specifically, 3 percent to 4 percent of all cases of colorectal cancer are due to hereditary nonpolyposis colon cancer (HNPCC), while approximately 1 percent is due to familial adenomatous polyposis (FAP).
The following sections will provide an overview to the genetics of colorectal cancer, as well as examples of genetic syndromes associated with an increased risk for colorectal cancer.