[Vitamin A: an indirect factor in the prevention of cancer].

Although vitamin A intervenes essentially in the mechanism of sight, its possible role in the prevention and treatment of cancer is widely discussed. Epidemiological studies have demonstrated a correlation between vitamin A deficiency and an increase in the frequency of cancers in man. Several hypotheses have been put forward concerning the mechanism of interaction between vitamin A and cancer on the basis of experimental models showing that vitamin A exerts a protective action against spontaneous or induced neoplasias in animals. The toxicological aspects of vitamin A administration and the relevance of these experimental results to human oncology are discussed.