α-Tocopherol (Vitamin E) and Its Relationship to Tumor Induction and Development

In recent years, emphasis on the role of the chemical and biological environment in carcinogenesis has emerged. Some have suggested that the majority of all human cancers may be environmentally related (Higginson, 1976). Such developments have, in part, their origins in the recognition that geographical differences in cancer patterns exist in the world, and they are certainly related to variations in environment (Clemmesen, 1965; Doll et al., 1970; Segi et al., 1969). In general, it has also been observed that as migrant groups leave their previous environment and adopt a new one, their propensity toward specific cancers also shifts to the prevailing risk of the new country or even local area. Further weight has been added to this idea through the identification in the human environment of numerous carcinogenic substances such as polynuclear aromatic hydrocarbons, nitrosamines, nitrosamides, and aflatoxins. The presence of many of these entities in our environment and food supplies or from in vivo formation leaves little doubt about potential exposure to man.