Risk of Developing Colorectal Cancer Following a Negative Colonoscopy Examination

Abstract

Colorectal cancer (CRC) is the third most commonly diagnosed cancer and the second leading cause of cancer deaths in North America.^1,2 Screening for CRC and its precursor lesions has become an increasingly prevalent practice. Colonoscopy has been recommended as the preferred initial screening test by several medical authorities including the American College of Gastroenterology and is being widely performed in the United States for screening among average-risk individuals.³ This is based on strong biological arguments and a higher detection rate of neoplastic lesions on colonoscopy compared with the other widely available screening modalities.^4-7 Colonoscopy also allows for removal of most precancerous polyps at the time of detection. A screening interval of 10 years after a normal colonoscopy has been adopted based on the estimate of the time it takes for an adenomatous polyp to transform into carcinoma. However, the duration over which the risk of CRC remains decreased following the performance of a normal colonoscopy remains unknown.⁸