Epidemiology of prostate cancer

Prostate cancer is the second most common malignancy and the sixth most common cause of cancer death for men worldwide. The highest incidence and mortality rates are in populations that originated in Africa, such as African Americans. Rates are also high in Western countries and generally low in East and South Asia. Incidence rates are increasing in some countries which until recently had low rates, but are not changing much in countries which already have high rates. The only well-established risk factors are increasing age, African ancestry, family history of the disease, and certain genetic factors, none of which is modifiable. Many potential risk factors have been investigated in epidemiological studies and randomized trials. Observational studies have shown that prostate cancer risk is positively associated with the plasma concentration of insulin-like growth factor-I, but is not strongly associated with testosterone or other sex hormones. Studies of nutritional factors suggest that risk may be higher in men with a high intake of animal foods and dairy products, but this relationship is not clear enough to be considered as established. Some studies of other nutritional factors such as fat, lycopene and other carotenoids, vitamin D, vitamin E and selenium have suggested possible associations, but overall do not show any clear relationships. Research on other possible risk factors has shown a small positive association of risk with height, but little association with obesity, smoking or alcohol intake, and evidence on sexual behaviour and sexually transmitted infections is inconclusive. Further research is needed, particularly to determine whether potential risk factors may be related more to aggressive than to indolent prostate cancer.