[Assessment of cancer risk in the work environment. Epidemiologic approach].

There are two essential steps in the analysis of carcinogenic risks in the work place: first, a descriptive approach which might raise the suspicion of an agent related to the frequency of a disease or mortality rate and then the analytical approach, based on retrospective and prospective cross-sectional studies. Such studies allow proof of the existence of a relation between a carcinogenic product and the frequency of lung cancer. The richer the contribution of such studies, the more difficult their accomplishment. All these studies assume that certain constraints are accepted: a precise protocol, collection of correct data, choice of a relevant population to be studied and controlled when necessary; rigorous supervision of each cohort under observation in the prospective studies, provision made for distorting factors. Such studies ought to result in averting occupational cancers rather than detecting them when clinically or radiologically apparent.