[Epidemiology and prevention of colorectal cancer]

Colorectal carcinoma is very common in western countries. It is in the front line of malignant pathology in France. The estimated number of new cases is almost 26,000 per year. The role played by diet in the onset of colorectal carcinomas is well established. The majority of studies indicate the protective role played by green vegetables. The role of other factors remains controversial: protective role of fibres, calcium and vitamins and favorizing role of fats, proteins, red meat, alcohol and calorie intake. The role of bile salts in increasing the size of adenomas and their malignant change is accepted. A number of therapeutic trials have involved modifications in bile salt concentrations. These should enable the proposal of a primary prevention strategy. The early detection of carcinomas and the secondary prevention of colorectal carcinoma (by detection of the adenomas which precede a high proportion of carcinomas) are areas of great interest. Detection of occult blood in stools as a mass screening test is currently being evaluated. Methods used to obtain a high participation rate among the population vary from one country to another, but are now well-defined. It will be necessary to wait for 2 years before being able to determine the effect on mortality and an even longer period to evaluate the effect on the incidence of colorectal carcinoma.