ABSTRACT
Rates of cancer vary substantially around the world, suggesting that environmental factors are critical in cancer etiology. The role of diet in cancer causation has received much attention; in their review of possible environmental determinants of cancer, Doll and Peto (1) estimated that 35% (with a range of 10-70%) of cancer in the United States may be attributable to dietary factors. The relations between energy intake, the intake of macronutrients, micronutrients, and nonnutrient additives and cancer at specific sites has been difficult to elucidate. Of the micronutrients, one of the most extensively researched is vitamin A. In this chapter, we first briefly review the epidemiological study designs used to gather data on the relation of vitamin A to specific cancers, and compare the quality of the data from these different designs. We then review the evidence relating vitamin A intake to lung cancer, breast cancer, colon and rectal cancer, and prostate cancer, which between them account for 55% of all new cancers in men in the United States, and 57% of new cancers in women (2).
