SEATTLE—A study of nutritional risk factors for prostate cancer delivered a mixed bag of results on several nutrients, finding none were associated with overall prostate cancer risk, but some had some association with risks of certain grades of prostate cancer. The trial was conducted at the Fred Hutchinson Cancer Research Center, Seattle, and was published in a recent issue of the American Journal of Epidemiology (2010;172(5):566-577).
The researchers examined among 9,559 participants in the Prostate Cancer Prevention Trial (United States and Canada, 1994–2003), using prostate biopsies to determine cancer—they recommended this procedure during the trial to patients with an elevated prostate-specific antigen (PSA) level or an abnormal digital rectal examination. Cancer was detected in 1,703 men, with 127 cancers deemed high-grade (Gleason score 8–10). Nutrient intake was assessed using a food frequency questionnaire and a structured supplement-use questionnaire.
An analysis of the data collected showed no associations of any nutrient or supplement with overall prostate cancer risk. However, high intake of polyunsaturated fats correlated with risk of high-grade cancer. Also, dietary calcium was positively associated with low-grade cancer, but inversely associated with high-grade cancer. Researchers concluded none of the nutrients often suggested for prostate cancer prevention—such as lycopene, long-chain omega-3 fatty acids, vitamin D, vitamin E and selenium—were significantly associated with cancer risk. They added high intake of n-6 fatty acids, through their effects on inflammation and oxidative stress, may increase prostate cancer risk.
