Forskning
April 17, 2012
Lifestyle and dietary factors in the prevention of lethal prostate cancer
K M Wilson et al, Lifestyle and dietary factors in the prevention of lethal prostate cancer, Asian Journal of Andrology, 2012, published online ahead of print.
Prostate cancer is a major contributor to cancer incidence and mortality among men throughout the world, particularly in Westernized countries.1 Moreover, men with prostate cancer suffer significant impairments in quality of life,2 both from the disease itself and as a consequence of treatment. The disease is notable in its considerable biologic heterogeneity in metastatic potential over a man’s lifetime. This heterogeneity is an important feature of the disease, and efforts to understand risk factors and predictors of more aggressive disease are central in prostate cancer research. The prevention of lethal prostate cancer represents an important public health challenge to reduce suffering from this disease. Moreover, the identification of lifestyle factors post-diagnosis that influence prostate cancer clinical course is appealing as a means of secondary prevention in combination with therapeutic intervention. In this paper, we present an overview of the evidence around selected exposures in the prevention of lethal prostate cancer. Given the diversity of potential factors, we have elected to focus on lifestyle and dietary factors, and not to discuss the evidence for pharmacologic agents. Moreover, we highlight compelling factors that may influence cancer-specific mortality after diagnosis. We present risk factors for lethal prostate cancer that have received the greatest scrutiny within epidemiological studies, as well as discuss novel hypotheses for which there is more limited evidence: obesity and weight change, physical activity, smoking, antioxidant intake, vitamin D and calcium, and coffee intake. The paper includes the following section on coffee:
There are several potential mechanisms by which coffee could be associated with a lower risk of lethal prostate cancer. Coffee is rich in several biologically active compounds including caffeine, minerals and phytochemicals. In observational and animal studies, long-term coffee drinking has been associated with improved glucose metabolism and insulin secretion in observational and animal studies. Moreover, coffee is a potent antioxidant and intake may be associated with levels of different sex steroid hormones. Most prior epidemiological studies of coffee and prostate cancer have focused on total incidence of disease. There have been to date three studies that have looked at lethal prostate cancer. Two studies reported no statistically significant associations of coffee consumption and prostate cancer mortality, although the studies were limited by a narrow range of coffee consumption, a small number of cancer-specific deaths, and inadequate adjustment for potential confounding by smoking and other factors. The Health Professionals Follow-up Study examined 47 911 men who reported intake of regular and decaffeinated coffee in 1986 and every 4 years thereafter, and included 642 patients with lethal prostate cancer. After adjusting for potential confounding, men who consumed six or more cups of coffee per day had an 18% lower risk for prostate cancer overall (RR: 0.82; 95% CI: 0.68–0.98) and a 60% lower risk of lethal prostate cancer (RR: 0.40; 95% CI: 0.22–0.75) compared to nondrinkers. Intriguingly, the inverse association with lethal cancer was similar for men who drank either regular or decaffeinated coffee, suggesting that caffeine is not underlying the link. These intriguing data, while biologically plausible, need to be confirmed in additional study populations with large number of events and control for confounding.
