Prostate cancer remains the most common noncutaneous malignancy diagnosed in American men and is the second leading cause of cancer-related deaths in that group. In the year 2008, almost 187,000 will be diagnosed with prostate cancer and an estimated 29,000 men will die of the disease.
The only undisputed risk factors for prostate cancer are older age, African-American race, and positive family history. Prostate cancer is generally a disease of elderly men; risk increases exponentially with age, with a median age at presentation of 68 years. Eighty percent of prostate cancer diagnoses and 90% of prostate cancer deaths occur in men older than 65. The incidence rates of the disease among African-American men are higher than rates for men in any other racial or ethnic background. African-American men are more likely to be diagnosed with prostate cancer and to die from it than their Caucasian counterparts. The estimated lifetime risk of prostate cancer is 17.6% and 20.6% respectively for Caucasians and African-Americans, while the estimated lifetime risk of death is 2.8% and 4.7%. Studies suggest that early onset prostate cancer may be inherited in an autosomal dominant fashion, and it is estimated that approximately 10% of all prostate cancer cases are hereditary. A large twin study suggests that genetic factors may account for as much as 42% of prostate cancer risk, although the absence of clear, highly penetrant markers suggests that in the majority of men, prostate cancer risk involves a complex interaction of multiple genetic and environmental factors.
Additional factors such as diet, obesity, hormones, inflammation and sexually transmitted diseases, and occupational exposure have all been implicated in prostate carcinogenesis, but without consistent results. Dietary fat may be a risk factor for prostate cancer. Multiple epidemiological, case–control, and cohort studies have suggested a moderate to strong increased risk of developing prostate cancer, particularly advanced disease, associated with total dietary fat, saturated fat, alpha linolenic fatty acid, and cooked red meat. Two large prospective studies and a smaller case–control study suggest that fish intake may be protective, possibly owing to marine omega-3 fatty acids—known antagonists of arachidonic acid, which suppress the production of proinflammatory cytokines. Evidence for the association with dietary fat is further correlated with worldwide incidence patterns; prostate cancer is more common in the United States and northern European countries and is relatively rare in Asia and Africa. When Asian men migrate to the West and change from a low-fat to a high-fat diet, their risk of prostate cancer increases. These studies, however, are complicated by the fact that many of the men migrating from low-fat diet areas also consume green tea and soy products, which contain isoflavones and estrogen that may act as antioxidants and chemoprotectants against prostate-specific carcinogenesis. Several epidemiologic studies have suggested an inverse relationship between soy intake and prostate cancer risk.
Most studies have not demonstrated an association between obesity and prostate cancer incidence, but there is growing evidence to support an ...