ABSTRACT
Prostate cancer represents the most commonly diagnosed types of cancer and provides a major clinical and public health challenge (Stokes et al. 2010). In 2010, approximately 217,730 men are expected to be diagnosed with prostate cancer, and 32,050 prostate cancer-related deaths are predicted to occur in the United States (Jemal et al. 2009). Currently, prostate cancer is the secondleading cause of cancer-related mortality in American males, next only to lung cancer (Jemal et al. 2009). However, it should be noted that prostate cancer is a preventable disease. This belief is based on the facts that (1) prostate carcinogenesis is composed of three distinct stages (initiation, promotion, and progression), some of which can be halted or even reversed by maintaining a healthy lifestyle or conducting appropriate medical treatments, and (2) prostate tumor formation takes a considerable time to occur, which is well supported by many clinical observations that prostate cancer is hardly found in men under age 50, but the prostatic intraepithelial neoplasia (PIN) lesion, a predictive biomarker of prostate cancers, is often found at autopsy in men under age 30. Chemoprevention is a clinical strategy to inhibit, delay, or reverse carcinogenesis, using naturally occurring or synthetic chemical agents. Indeed, it is estimated that formation of most types of cancers in humans, including prostate cancer, is attributable to environmental risk factors, such as noxious chemicals, occupational irradiations, and tumor-causing viruses. The notion that formation of human cancers is affected by environmental factors, combined with genetic susceptibility, offers great optimism for chemoprevention, since most cancer-causing substances are produced and introduced into the environment by human activities. Therefore, eliminating carcinogens or at least avoiding them in the environment can reduce the incidence of cancer.
