The potential for prostate cancer chemoprevention.

The dramatic international variation in prostate cancer incidence and mortality rates suggests that changeable environmental factors exert an influence. This has prompted a search for ways to prevent the disease. Epidemiologic studies suggest that dietary factors such as the carotenoid lycopene, selenium, vitamin E, and high intake of fat have roles in prostate cancer risk. Several studies show that impairment of androgen synthesis lowers the risk of prostate cancer. 5-alpha-reductase inhibitors such as finasteride have been shown to decrease prostate size by decreasing androgenic stimulation to the prostate. Other promising, but less developed, interventions include vitamin D supplements and modification of diet. Any manipulation to decrease one's relative risk of prostate cancer will by necessity have to be given to a large proportion of men who would never develop prostate cancer even without the intervention. To be acceptable, a successful preventive intervention should have few or no side effects; some additional benefits would be useful. All potential preventive interventions will need to be rigorously evaluated before they can be advocated for prostate cancer prevention.