There are more than 130,000 new cases of colorectal cancer in the United States each year. Colorectal cancer represents about 15% of all cancers. Of these, approximately 5% are directly related to inherited genetic defects. Most of these patients have a diagnosis of pre-cancerous colon or rectal polyps before the onset of cancer. While most small colorectal polyps are benign in individuals without genetic defects, some types may progress to cancer.

There are several types of hereditary polyposis syndrome related to increased risk of colorectal cancer. Familial Adenomatous Polyposis (FAP) and it variant, Gardner’s Syndrome are the two most common types. FAP and Gardner’s Syndrome are characterized by hundreds, even thousands, of polyps in the colon. The polyps will generally not develop until puberty, and cancerous transformation of these polyps generally starts 10 years after the onset of polyp development. It is inevitable that a malignancy will ultimately develop in one of these polyps unless the colon mucosa is removed. 

There are also patients who do not have polyps who are at genetic risk for developing colon cancer.  These patients have a hereditary non-polyposis colon cancer (HNPCC).  Examples of this include Lynch I and Lynch II syndromes and few of any of these patients have polyps. 

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For more information on colorectal cancer, please visit the  Colorectal Cancer Home Page.