[Methods for the early detection of colonic polyps and colonic cancers].

The dramatically rising incidence of colorectal cancer and the fact that survival rates can only be improved by earlier diagnosis call for increased efforts aimed at early detection of colonic neoplasias. Present diagnostic methods--occult blood testing, digital exam, rigid and flexible sigmoidoscopy, double contrast barium enema and colonoscopy--are analyzed with regard to diagnostic yield, time requirement and patient acceptability. Flexible sigmoidoscopy has proved to be of high diagnostic value, to take relatively little time and to cause only minimal patient discomfort. It will therefore gradually replace rigid sigmoidoscopy. Various populations at risk for colorectal cancer are outlined and appropriate diagnostic screening methods are described. Finally, a plan for monitoring of the normal risk population is proposed.