ABSTRACT
According to the most recent statistics from American Cancer Society (https://www.cancer.org/docroot/home/ index.asp), colorectal carcinoma ranks as the fourth most commonly diagnosed cancer and the second leading cause of death from cancers in the United States (Jemal et al. 2010). It was estimated that more than 142,000 new cases will be diagnosed with more than 50,000 dying from the disease in 2010 (Jemal et al. 2010). Similar to other cancers, colon cancer is often diagnosed at an advanced stage, after the patient has developed symptoms. Dierent from other cancers, most colon cancers can be avoided because they arise from adenomatous polyps, a precursor that takes a long time period over several years of malignant transformation and can be detected during the transformation period. For example, it takes more than 2 years for an adenomatous polyp to grow to 5 mm size with far less than 1% cancer risk, an additional 3 or more years to 10 mm size with
cancer risk approaching to 1%, and another 5 or more years to 20 mm size and 10% cancer risk (Grandqvist 1981, Stryker et al. 1987, Potter and Slattery 1993, Jass 2007, Yoo et al. 2007). erefore, screening of an asymptomatic patient at an adequate time interval and removal of detected adenomatous polyps of less than 10 mm can eectively cure the patient (Morimoto et al. 2002, Winawer and Zauber 2002). ere are several options currently available for the screening purpose, such as (1) fecal occult blood testing (Mandel et al. 2000), (2) fecal immunochemical or immunoassay testing (Allison et al. 2007), (3) stool DNA testing (Ahlquist et al. 2008), (4) double-contrast or air-contrast barium enema (Brady et al. 1994), (5) exible sigmoidoscopy (Levin et al. 2005), and (6) optical colonoscopy (OC) (Hafner 2007). Each has advantages and drawbacks (Liang and Richards 2010), where OC is the gold standard for the evaluation of the entire colon wall mucosal (or inner) surface with therapeutic capability of resection of found abnormalities.
