Abstract
The effectiveness of sigmoidoscopy (SS) in colorectal cancer screening has recently been proven in randomized controlled trials (RCTs). In intention-to-screen analyses, screening with SS reduced mortality from colorectal cancer and distal colorectal cancer by 20∼30% and 30∼50%, respectively. However, there was no significant reduction in mortality from proximal colon cancer. A similar tendency was observed in the incidence rates of these cancers. Perforations due to SS rarely occurred in these RCTs and were not reported in the 117,644 SS procedures in Japan. With respect to total colonoscopy (TCS), the results of case-control studies and cohort studies suggest a decrease in colorectal cancer incidence and mortality. However, these effects were not reported for right colon cancers until several years ago. Although TCS has not been evaluated in RCTs for its influence on the incidence and mortality of colorectal cancer, some RCTs are currently in progress and further results in this regard are awaited.
