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[Problem posed by the prevention and detection of colorectal cancers].

The incidence of colonic and rectal carcinoma is in constant progression. The detection and destruction of polyps is the only effective means of reducing the number of adenocarcinomas. The technical means of detection are well known and fully proved: rectosigmoidoscopy, thin layer double contrast enema, colonoscopy. The true problem is that of the cost of this prevention. It is important to define high risk groups in which these tests should be carried out as a routine. Furthermore it is necessary to know whether blood tests or examination of the stools may be considered as a means of detection of polyp or at least certain types of potentially malignant polyp. without suggesting a considerable increase in the number of medical investigations, one may hope for better use of sigmoidoscopy and double contrast barium enema. These two examinations represent undoubtedly the essential factor in the diagnosis of colonic and rectal tumours.