Vitamin A and Lung Cancer

Vitamin A has long been recognized to play a central physiologic role in the regulation of cell differentiation. Because loss of differentiation is a basic feature of malignancy, vitamin A may be related to cancer incidence. In numerous animal studies, naturally occurring preformed vitamin A and synthetic analogs have inhibited the occurrence of induced tumors and even reversed metaplastic changes. This chapter describes the unfolding of evidence on vitamin A and lung cancer, both because of the potential importance of the hypothesis and what it has taught us about nutritional epidemiology. Even today, the story is taking another twist with the potential integration of genetic and dietary data on this topic.