The Role of Vitamin E in Prostate Cancer

This chapter reviews the current literature linking vitamin E to prostate cancer with the overall goal of providing a rationale for the design of potential future large-scale clinical chemoprevention studies. Vitamin E is not a single organic compound and refers to at least four tocopherols (alpha, beta, gamma, and delta) and four corresponding tocotrienols. Much of the literature linking vitamin E with cancer does not distinguish between these various isoforms and has primarily focused on alpha-tocopherol which is the primary vitamin E isoform found in plasma from fasting individuals and in most dietary supplements. Considerable evidence now supports the view that the various isoforms of vitamin E (and their chemical derivatives) have distinct biochemical properties and distinct abilities to modulate oxidative stress, signal transduction pathways, and pathophysiological processes important in carcinogenesis (e.g., apoptosis and angiogenesis). This chapter reviews the recent clinical trials as well as the in vitro and in vivo evidence connecting the various isoforms of vitamin E with prostate cancer. Particular emphasis is placed on gamma-tocopherol, the primary dietary isoform of vitamin E. A major conclusion is that some non-alpha-tocopherol forms of vitamin E hold considerable promise for both the chemoprevention and chemotherapy of prostate cancer