The Impact of Colonoscopy on Colorectal Cancer Incidence and Mortality

In the United States, periodic colorectal cancer (CRC) screening rates increased from 45% of the eligible population in 2002 to 63% in 2008 (Richardson et al., 2010). Over a similar time period, colonoscopy has become the most widely utilized colorectal cancer screening tool in the United States. In other countries, colonoscopy is the most commonly recommended screening test, particularly in Europe. However, in many locales in which other screening tests such as fecal occult blood tests (FOBT) are preferred due to cost or availability, colonoscopy is used to follow up on patients screening positive (Brenner et al., 2001; Hoff & Dominitz, 2010; Classen & Lambert, 2008). The ascendance of colonoscopy in the US corresponds with a significant reduction in colorectal cancer incidence and mortality. In the Annual Report to the Nation on the Status of Cancer from 1975-2006, microsimulation modeling demonstrated the relatively large contributions of screening, along with risk factor modifications and improved cancer treatments, to this decline (Edwards et al., 2010). The focus of this chapter is the effectiveness of colonoscopy, as a means to decrease CRC incidence and mortality. In addition, we identify factors including tumor biology, instrumental, patient-related issues and endoscopist characteristics that may influence the impact of colonoscopy on these rates.