The effects of obesity and diet on prostate cancer risk
Prostate cancer is nowadays the most common malignancy in males of the western world, but little is as yet known regarding the causes of initiation and progression of this disease. To explain the geographical variations in the incidence of clinical prostate cancer, the changes in its prevalence in migrants moving from countries with a low prostate cancer incidence to those with a high incidence, and the lack of international variation in the prevalence of microfocal or latent prostatic tumors, environmental factors have been implicated. Obesity, western-type diet, increased total energy and saturated animal fat intake have all been suspected as potential risks. In contrast, consumption of vegetables and soy products and intake of certain vitamins and micronutrients, such as vitamins E and D, lycopene and selenium, may exert a protective effect. The hypothesis that dietary changes might affect the development of prostate cancer is strengthened by the fact that of all mammals almost only humans and dogs (at a much lower rate) get prostate cancer. Both have dramatically altered their diets during the last 15,000 years of their evolution, while other primates and mammals in which the disease is absent, made no significant changes. Case-control and cohort studies have failed to find a consistent association between prostate cancer risk and body mass index, dietary fat, total energy intake or other life-style changes. The conflicting results of past and recent trials are perhaps due to methodological and statistical limitations, measurement errors, different questionnaires, heterogeneity of prostate cancer patients, unsuspected biases and the retrospective nature of these investigations. Nevertheless, pending more extensive, well-controlled prospective studies, dietary and life-style changes should be advised, based on reduced morbidity and mortality from cardiovascular disease, the number 1 cause of death in western countries, and the number 1 or 2 cause of death in patients diagnosed with prostate cancer.