A case-control study in the Cote-d'Or area (Burgundy, France) investigated the relationship between environmental and familial risk factors and the different steps of the adenoma-carcinoma sequence. Two adenoma groups (< 10 mm and > or = 10 mm), a polyp-free control group, a colorectal cancer group and a general population control group were recruited. Tobacco was associated with the risk of adenomas, and alcohol with the risk of large adenomas. They proved to be independently related to large adenoma formation when compared with controls. There was no association with cancer risk. Refined cereals, delicatessen, offal and fats appear to be risk factors along the adenoma-carcinoma sequence. This data does not support an increased risk with high consumption of fresh meat, or a protective effect of dairy products and calcium. A high consumption of vegetables was a protective factor for cancer, mainly in men. Excess weight and body mass index influenced the earlier step of the adenoma carcinoma sequence and excess calorie intake was risk factor for cancer. The decision to study precancerous lesions as well as cancer appears fruitful. Results suggest that the three stages of large bowel carcinogenesis are partly related to diet in different ways. They are concordant with risk factors recorded for colorectal cancer, but suggest some local specificities.