The Association between Dietary Antioxidants and Prostate Cancer Aggressiveness

Prostate cancer is the most common non-cutaneous cancer and the third leading cause of cancer-related mortality among men in the US. The geographic and racial heterogeneity in prostate cancer rates around the world, along with evidence that oxidative stress might be involved in the development and progression of prostate cancer, has informed many studies over the past few decades to investigate whether antioxidants found in the diet might influence prostate cancer risk. Despite numerous studies on this topic however, the variety of antioxidants in the diet makes difficult determining whether antioxidants influence prostate cancer. The purpose of this study was to determine the relationship between total antioxidant capacity, an index of antioxidant intake from diet and supplements, and prostate cancer aggressiveness among 855 Black and 945 White men in the North Carolina – Louisiana Prostate Cancer Project. Total antioxidant capacity was determined using 42 antioxidants present in the diet or supplements. Total antioxidant capacity from diet and supplements combined was inversely associated with prostate cancer aggressiveness in all men and this association did not differ between Black and White men. To determine whether the association between antioxidant intake and prostate cancer aggressiveness is related to changes in oxidative stress, associations between total antioxidant capacity and biomarkers of oxidative stress in blood (n=278), urine (n=298), and prostate tissue (n=55) were determined among a subsample of men. Greater antioxidant intake was found to be inversely associated with 8-isoprostane in urine and thioredoxin 1 in benign prostate tissue. No significant associations were found for other blood or urinary biomarkers or for malignant prostate tissue. These results suggest that greater intake of antioxidants may be associated with less oxidative stress. To assess potential confounding, the association between antioxidant intake and socioeconomic, clinical, and lifestyle characteristics was assessed. Antioxidant intake was associated with most of these characteristics that may influence prostate cancer incidence and severity at diagnosis. The major sources of antioxidant intake were tea and dietary supplements. The potential for residual confounding of the association between antioxidant intake and prostate cancer aggressiveness cannot be excluded