Although prostate cancer is influenced by both heredity and environmental factors, some measures might prevent the development or slow the progression of prostate cancer.

Prostate cancer is almost certainly caused by changes (mutations) in the DNA that affect the regulation of the growth of normal prostate cells.  Most probably, several mutations have to take place before a full-blown cancer occurs.  These mutations can accumulate over time, causing the gradual progression to prostate cancer.  Some mutations may cause a precancerous condition called prostatic intraepithelial neoplasia (PIN); others may cause a slowly growing form of the cancer; and still others may cause a rapidly progressive form of the disease.  Some prostate cancers may take decades to develop, while others may develop more rapidly if a more serious mutation occurs.

A man may inherit one or more of these mutations from either their mothers or their fathers.  In these cases, fewer additional mutations would be needed before cancer occurs.  Even with these mutations, recent attention has been focused on nutrients as possible prostate cancer preventive agents.  The most promising are soy products (called phytoestrogens and isoflavones), lycopene, vitamin E, selenium, and vitamin D.

Soy Products

Some researchers have speculated that the high ingestion of soy products is responsible for the lower death rate from prostate cancer in Japan (4 to 5 times lower than in the United States).  In addition, some studies have suggested that prostate cancers develop and progress more slowly in Japan.

Soy has been shown to slow the proliferation of prostate cells, and part of this effect may be mediated through lowering the levels of male hormones.  Soy contains steroid-like chemicals that may alter the chemical reactions in prostate tissues.

Soy proteins are changed by intestinal bacteria to produce estrogenic and antiestrogenic compounds.  This production increases the levels of binding protein levels in the blood that tie up the male hormone, testosterone, which normally stimulates prostate cancer cells to grow.  Soy proteins also have numerous other potential actions.  They alter enzyme functions, alter protein synthesis, alter the action of growth factors, directly affect the growth rate of prostate cells, and alter the production of blood vessels that allow tumors to grow.

Genistein, one of the most prominent components in soy, has been shown in animal prostate cancers to slow the rate of tumor growth.

Sufficient experimental evidence justifies the use of soy proteins in clinical trials for preventing prostate cancer, and these studies will provide important information in the future.

Lycopene

Lycopene, found in tomato products, has one of the greatest capacities for preventing mutations in DNA.  Chemicals that have these properties are called antioxidants, and lycopene is one of the stronger antioxidants.  In addition, lycopene has other biological activities for cell to cell communications and growth control.  Experimental animal studies show that lycopene can slow the growth of prostate cancer cells.

Epidemiologic studies (studies that deal with the incidence, distribution and control of disease in a population) have shown that consumption of lycopene is associated with a lower risk of prostate cancer.  In one important study, lycopene was the only antioxidant found in significantly lower levels in prostate cancer patients than in men without prostate cancer.  Also, other studies suggest that taking lycopene before prostate cancer surgery may result in more favorable treatment results.

Lycopene concentrates are available at pharmacies and health food stores and can be purchased over the counter without a prescription.

Vitamin E

Vitamin E is a fat soluble vitamin that also has the potential to decrease DNA damage through its antioxidant effects.  In addition, vitamin E affects the immune system.  Vitamin E deficiency  is associated with decreased immune function which increases the susceptibility to cancer and infections. 

Vitamin E may not only prevent the development of prostate cancer but also may slow its progression, especially in smokers.  Vitamin E may also lower the activity of some cellular signals that increase cell growth.   Studies suggest that vitamin E may be especially important in inhibiting  the growth of prostate cancer cells induced by a high-fat diet.

Many fat soluble vitamins such as vitamin E can cause side effects if taken in large doses. Some (but not all) studies suggest that too much vitamin E may interfere with blood coagulation and lead to post-surgery bleeding due to its effect on platelet function.

Vitamin E exists in several forms;  200 to 800 units of the alpha tocopherol form of vitamin E are well tolerated.

Selenium

Selenium may also act as an anticancer agent due to its antioxidant properties.  Selenium suppresses cell growth and enhances the immune response, thus functioning similarly to vitamin E.  Studies have suggested that prostate cancer risk was reduced by 60% among those who take supplemental selenium.

Selenium may also exert its antitumor effects by other mechanisms, such as inducing programmed death in cancer cells, and affecting important enzyme systems.

The recommended dose of selenium is 200 ug/day (ug. is a microgram or 1/1000 of a gram.)  which is 2 to 3 times the recommended daily allowance.

Vitamin D

While, vitamin D is important primarily for bone and mineral metabolism, it also induces conversion of prostate cancer cells into normal cells and blocks the growth of prostate cancer cells.

Vitamin D may act by blocking the progression of cells through the cell cycle and initiating programmed cancer cell death.  Vitamin D may be important in preventing prostate cancer and is also being  studied as an agent for the treatment of advanced prostate cancer.

The recommended daily dose is 10 ug/day.  Higher doses may cause high blood calcium levels.