RESUMEN
Colorectal cancer screening is thought to be an effective tool with which to reduce the mortality from colorectal cancer through early detection and removal of colonic adenomas and early colon cancers. In this article, we review the history, evolution, and current status of imaging tests of the colon-including single-contrast barium enema, double-contrast barium enema, computed tomographic (CT) colonography, and magnetic resonance (MR) colonography-for colorectal cancer screening. Despite its documented value in the detection of colonic polyps, the double-contrast barium enema has largely disappeared as a screening test because it is widely perceived as a labor-intensive, time-consuming, and technically demanding procedure. In the past decade, the barium enema has been supplanted by CT colonography as the major imaging test in colorectal cancer screening in the United States, with MR colonography emerging as another viable option in Europe. Although MR colonography does not require ionizing radiation, the radiation dose for CT colonography has decreased substantially, and regular screening with this technique has a high benefit-to-risk ratio. In recent years, CT colonography has been validated as an effective tool for use in colorectal cancer screening that is increasingly being disseminated.
Asunto(s)
Sulfato de Bario , Pólipos del Colon/diagnóstico por imagen , Colonografía Tomográfica Computarizada , Neoplasias Colorrectales/diagnóstico por imagen , Detección Precoz del Cáncer , Enema , Espectroscopía de Resonancia Magnética , Pólipos del Colon/historia , Colonografía Tomográfica Computarizada/historia , Colonografía Tomográfica Computarizada/instrumentación , Colonografía Tomográfica Computarizada/tendencias , Neoplasias Colorrectales/historia , Medios de Contraste , Detección Precoz del Cáncer/historia , Detección Precoz del Cáncer/instrumentación , Detección Precoz del Cáncer/tendencias , Enema/historia , Historia del Siglo XX , Historia del Siglo XXI , Humanos , Sensibilidad y EspecificidadAsunto(s)
Sulfato de Bario/historia , Pólipos del Colon/diagnóstico por imagen , Pólipos del Colon/historia , Enema/historia , Pólipos Intestinales/diagnóstico por imagen , Pólipos Intestinales/historia , Enfermedades del Colon/diagnóstico , Enfermedades del Colon/historia , Medios de Contraste/historia , Medicina Basada en la Evidencia , Historia del Siglo XX , Historia del Siglo XXI , Humanos , RadiografíaRESUMEN
Current practices vary regarding the approach to small polyps discovered during screening flexible sigmoidoscopy. The most common practice is to perform colonoscopy whenever any adenoma is detected, a strategy that generally uses biopsy of polyps < or = 5 mm in size. However, data suggest that tubular adenomas < 1 cm in size in the distal colon have less predictive value than other distal adenomas for advanced adenomas in the proximal colon. Thus, some centers reserve colonoscopy for distal adenomas with tubulovillous or villous histology, > 1 cm in size, or with high-grade dysplasia. At the other end of the spectrum, another school of thought advocates screening colonoscopy, recognizing that most patients with advanced proximal adenomas do not have polyps in their distal colon. Advocates of this approach use any excuse to perform colonoscopy, whether it be a positive fecal occult blood test, minor symptoms, or small polyp at flexible sigmoidoscopy, even if hyperplastic. This review describes the history of the controversy regarding management of findings at flexible sigmoidoscopy, the data pertinent to the controversy, and the basis for the three approaches described above, all of which are currently within the standard of medical care.