Despite advances in diagnostic techniques and treatment, the 5-year survival rates remain poor.
Strong evidence indicates that a high proportion of colorectal cancers arise in adenomas.
These lesions could be a potential target for secondary prevention as well as for primary prevention. Several arguments lend credence to the notion that the adenoma-carcinoma sequence is a multistep process. Cancer can be prevented by intervention either at the stage of adenoma appearance, adenoma growth or at that of transformation into carcinoma. Many case-control studies and some cohort studies have provided substantial epidemiological evidence for the overwhelming role of diet in the occurrence of the disease. There is fairly consistent evidence concerning the effect of vegetables as a protective factor and of caloric intake as a risk factor.