BERKELEY, CA (UroToday.com) - The precise mechanisms that cause prostate cancer (PCa) are unknown, but it is believed that oxidative stress may be involved in the development and progression of this common disease. Oxidative stress is caused by an excess production of free radicals (H•) and other reactive oxygen species (e.g. H2O2) or a deficient antioxidant defense. The antioxidant defense system includes antioxidant enzymes (e.g. superoxide dismutase, glutathione peroxidase) and several metabolites, which are often obtained from various dietary sources.
To further test the oxidative stress-PCa hypothesis, we investigated the associations between intake of antioxidant nutrients (e.g. lycopene and vitamin E) and pro-oxidant exposures (e.g. cigarette smoking and heme iron intake), and risk of overall and advanced stage PCa. We evaluated antioxidant and pro-oxidant variables separately, and also studied their combined effect by means of an antioxidant score (antioxidant nutrients only) and an oxidative balance score (both antioxidant and prooxidant exposures).
Study participants were 58 279 men in the Netherlands Cohort Study who reported detailed baseline exposure data in 1986 and who were followed until 2003 for the diagnosis of incident PCa. Our study showed that most individual exposures were not associated with PCa risk and there were no associations for the combined measures.
One interesting finding in this study was that intake of catechins (antioxidant polyphenols) was associated with a reduced risk of the most advanced stage (stage IV) of PCa.
Important strengths of our study are study power and data on intake of antioxidants/prooxidants from all commonly-consumed food sources (e.g. fruits, vegetables, tea, oils, fats). Our study was limited by the lack of biomarker data and a baseline exposure measurement only. Based on our findings, it is unlikely that dietary and environmental factors, that have a probable effect on oxidative stress, are strong predicators of PCa incidence. It is not ruled out, however, that specific antioxidant nutrients, such as polyphenols, may reduce the risk of advanced PCa. The combined measures of antioxidant and prooxidant exposures described in this research article can be interesting tools in future genetic-association studies focused on genes involved in oxidative stress defense.
Milan Geybels, PhD student as part of Beyond the Abstract on UroToday.com. This initiative offers a method of publishing for the professional urology community. Authors are given an opportunity to expand on the circumstances, limitations etc... of their research by referencing the published abstract.
Department of Epidemiology
Maastricht, The Netherlands