Re: Alternatives to colonoscopy for population-wide colorectal cancer screening.

Colorectal cancer is one of the top three cancers in the world in terms of incidence. Colonoscopy, which many regard as the gold standard in diagnosis of colonic polyps and neoplasm, is costly, invasive and labour-intensive, and deemed an unsuitable population-wide index screening tool. Alternative modalities, including guaiac and immunohistochemical faecal occult blood tests, computed tomographic colonography, colon capsule endoscopy, flexible sigmoidoscopy, and double-contrast barium enema are available. The procedures, test characteristics, and their implications are reviewed. Immunohistochemical faecal occult blood testing appears to be the most suitable population-wide screening test for an average-risk population, with flexible sigmoidoscopy as an alternative. More evidence is needed to determine the role of computed tomographic colonography and colon capsule endoscopy in colorectal cancer screening.