CT Colonography

Abstract

Colorectal cancer (CRC) is one of the leading causes of cancer in the United States and the world. In the United States, there are approximately 145,000 new cases of CRC (about 105,000 in the colon and 40,000 in the rectum) and 50,000 deaths from CRC annually (Jemal et al. 2010). Worldwide there is an annual estimated 1,200,000 new cases and 600,000 deaths from colorectal cancer (Jemal et al. 2011). Colorectal cancers are typically adenocarcinomas that arise from malignant transformation of adenomatous colorectal polyps. Only a small percentage of these polyps undergo malignant transformation, but polyps are thought to be a necessary precursor to the majority of adenocarcinomas (Ferruci 2001). Furthermore, the larger the size of a polyp, the greater the chance it will become malignant. Smaller polyps on the scale of 5-9 mm have up to a 5% probability of malignant transformation within 10 years and larger polyps between 10 mm and 15 mm carry up to a 15% risk of becoming malignant within 10 years(Ferruci 2001). Therefore, the ability to identify and excise these polyps before they become malignant can potentially prevent adenocarcinoma from ever occurring.