Hereditary Colon Cancer Colon cancer is one of many cancers to plague United States citizens. There are four known types of colon cancer. Fourteen percent of all cancers diagnosed are colon cancer. Colon cancer is the third most commonly diagnosed cancer. Sporadic cancer accounts for 80 percent of all colon cancers and is considered non-hereditary. The remaining 20 percent of cancer are related to heredity. Familial Adenomatous Polyposis Coli (FAP) and Hereditary Non-Polyposis Colon Cancer (HNPCC) are hereditary colon cancers. There is another hereditary colon cancer, which is rare. This ty