Endoscopic detection of colorectal adenomas: standards and sophisticated methods.

Colorectal cancer represents one of the leading malignancies worldwide. Early endoscopic detection and removal of its precursor lesions, adenomas, and serrated hyperplastic polyps results in a decrease of colon cancer-related death. However, miss rates in adenoma detection up to 26% underline the need for high compliance to basic measures and further improvement in methodology and technology. Basic parameters affecting adenoma detection rates include sufficient training and awareness of the endoscopist, use of high-definition endoscopes, careful examination behind folds, cleansing the colon wall, accurate distention of the colon, and adequate withdrawal time. Advanced imaging techniques, introduced to further improve adenoma detection, have yielded mixed results. These include wide-angle colonoscopes, cap-assisted colonoscopy, and retroscopic methods which may add new obstacles to colonoscopy. Moreover, chromoendoscopy either 'virtual' or by topically applied dyes has been suggested to enhance the detection of colonic neoplasia. Yet, studies on patients with average cancer risk have failed to reproduce promising initial results. Similarly, although autofluorescence has not enhanced the diagnostic yield in screening a population at average risk, it may be useful in patients at increased cancer risk. Recently, technical feasibility of molecular imaging employing 'biomarkers' has been demonstrated, but needs further evaluation. The newest developments, employing light-scattering spectroscopy, suggest the existence of a 'field effect' of colonic carcinogenesis and may enable detection of the earliest neoplastic events and distant adenomas even when applied to normal-appearing mucosa. Upon confirmation, these technologies may result in a substantial change in patient management and risk stratification.