Chemoprevention of prostate cancer by diet-derived antioxidant agents and hormonal manipulation (Review)

Cancer of the prostate is the most commonly diagnosed solid malignancy and the second leading cause of cancer-related death in men living in developed countries. With an ageing population, the number of men living with early stages of prostate cancer is expected to increase. There is an increasing need to prevent the onset of cancer or delay the progression of carcinogenesis in this organ. Chemoprevention is the administration of pharmacological agents to prevent, delay or reverse carcinogenesis. An example is the reversal of high grade intraepithelial neoplasia by hormonal manipulation using anti-oestrogens in breast carcinogenesis or anti-androgens in prostate carcinogenesis. Epidemiological data showing ethnic and geographic variations in the incidence of, and mortality from, prostate cancer have suggested that the consumption of certain dietary factors, particularly anti-oxidants, may be protective. These factors include the vitamins D and E, soy, lycopene and selenium. The administration of 5-α reductase inhibitors to patients with benign prostatic hyperplasia may also constitute a potentially chemopreventive intervention. The efficacy of chemopreventive agents needs to be investigated in randomised, placebo-controlled trials in suitable cohorts of high-risk individuals. In parallel, reliable assays of potential biomarkers of the efficacy of intervention need to be developed and validated rigorously.