The authors remind: cancerous disease's possibilities of description before any treatment through its topography, its morphology and its clinical medicine; the modalities for taking surgical, actinic, chemical, immunologic therapeutics in account; the technics of the cancerous disease supervision after treatment, from the vital points of view (study of observed and relative survival, and of recovery) and from the carcinologic and fonctionnal points of view. They insist on the possibilities of these languages that go from the simple notation of information to the taking of these sundries modalities in account. The disposable datums in France are schematicly described. They concern: the study of survival from hospitable series; mortality by cancer for the whole of the country. The authors consider that no entry must be undertaken without the purposes, in the same way as the considered modalities for analysis, being precisely fixed. They insist on the notion of information level, of which three levels are schematicly defined, according as descriptive epidemiology or epidemiologic research or clinical research is in question.