Prostate Cancer Prevention Report

In American men, prostate cancer is the first leading cause of cancer death - about 29,900. Researchers are busy studying the effects of nutrition on the prevention of prostate cancer. Recent studies have shown that eating both fresh and processed tomato products reduces the risk of prostate cancer. Tomatoes are full of carotenoids, primarily lycopene. Lycopene is hypothesized to be one of the principal phytochemicals in tomatoes that possess anticancer properties. (1)
Dietary products are being studied to determine their chemopreventive properties in prostate cancer. Some of these chemopreventive agents include SERM (soy isoflavones), retinoids, vitamin E, organoselenium (and the combination of selenium and vitamin E), lycopene, perillyl alcohol and vitamin D. (3)

Pathophysiology of prostate cancer
Prostate cancer develops when cancer forms in a male's prostate gland. This cancer is due to the prostate cells multiplying uncontrollably, which can lead to metastasis, or spreading of the cancer, to other parts of the body such as the bones or lymph nodes. Some common symptoms include pain, difficulty in urinating, and erectile dysfunction. Many factors have been implicated in the development of prostate cancer, such as age, genetics, and diet. (2)
Doctors can test for prostate cancer by physical examination or screening blood tests. Currently, the prostate specific antigen (PSA) and prostatic intraepithelial neoplasia (PIN) tests are the only screening blood tests available for prostate cancer.(2)
Prostate cancer can be treated with radiation therapy, hormone therapy, surgical removal of the prostate, or chemotherapy. But the best cure for any disease is prevention.(2)

Pharmacodynamics of lycopene
Lycopene is a powerful antioxidant that blocks the action of free radicals such as activated oxygen molecules which can damage cells. The antioxidant activity of lycopene is at least twice as great as beta carotene, another carotenoid that is also thought to be an effective cancer-preventing nutrient. Lycopene is considered one of the more effective antioxidants because it is not converted to vitamin A after it is eaten. Conversion to vitamin A weakens the antioxidant properties of carotenoids like beta carotene. (4)
The exact pharmacodynamics of lycopene are unknown. Lycopene is in preclinical toxicity and pharmacodynamics studies to determine its distribution to prostate, and it will soon be in Phase I clinical studies. (3)

Therapeutic uses of lycopene
Lycopene is found in tomatoes, apricots, guava, papaya, fresh watermelon, and pink grapefruit. People who have diets rich in tomatoes, which contain lycopene, appear to have a lower risk of certain types of cancer, especially cancers of the prostate, lung, and stomach. (4)
Many researchers believe that lycopene may lower the risk of heart disease, macular degenerative disease, and lipid oxidation. It is also said to lower low-density lipoprotein (LDL) cholesterol, enhance the body's defenses, and protect enzymes, DNA, and cellular fats. (4)

Toxicity
Lycopene from fruits and vegetables has no known adverse effects and is considered safe for humans. The potential side effects, general safety, and toxicity of lycopene and its supplements are not known and are currently being investigated. (4)

Results
In the Health Professionals Follow-up Study, about 47,000 men were followed from 1986 to 1998 and periodically filled out lifestyle questionnaires. By 1998, 2481 of the men had been diagnosed with prostate cancer. It showed that there was a 23% reduction in prostate risk when men consume at least two servings of tomato sauce per week when compared to less than one serving per week. This also shows a significant inverse relationship between plasma lycopene concentrations and prostate cancer risk in men over 65 years old with no family history of prostate cancer. (1)
In the Dunning MatLyLu prostate cancer experiment, lycopene was tested on an aggressive cancerous prostate tumor in rats. In vivo analysis of the tumor by MRI showed that lycopene cause necrosis in 36% of the tumor when compared to the untreated rats which only had a tumor necrotic area of 20%. (1)

Discussion
The future of prostate cancer research is changing rapidly. Research using new technologies will lead to new cancer biomarkers for diagnosis and clinical study. There will also be new treatment regimens and drug delivery systems for not only chemotherapeutic drugs, but also chemopreventive agents, foods and dietary supplements. Once the pharmacodynamics and mechanism of lycopene are determined, new drugs or other phytochemicals can be used to prevent prostate cancer. This will lead to the research and discovery of more phytochemicals to prevent other diseases and cancers such as lung cancer or breast cancer.
Lycopene has potential for other uses in relation the prostate cancer. For example, since high levels of lycopene have been shown to decrease the risk of prostate cancer, maybe lycopene can be used like a biomarker in the screening and diagnosis of the disease. Researchers interested in the effects of lycopene and prostate cancer will probably be interested to study this relationship.

Conclusion
Lycopene has been proven to decrease the risk of prostate cancer. Although this does not completely prevent the disease, it provides hope for many men who are fearful of developing the disease, not those with a genetic disposition of developing the disease. Currently, lycopene is in clinical trials and is still being studied for its effect on both normal and cancerous prostate cells.

References
(1) J. Campbell, K. Canene-Adams, B. Lindshield, T. Boileau, S. Clinton, J. Erdman, Tomato Phytochemicals and Prostate Cancer Risk, J. Nutr., 2004 134: 3486S-3492S
http://jn.nutrition.org/cgi/content/abstract/134/12/3486S
(2) http://en.wikipedia.org/wiki/Prostate_cancer
(3) G. Kelloff, J. Crowell, V. Steele, R. Lubet, W. Malone, C. Boone, L. Kopelovich, E. Hawk, R. Lieberman, J. Lawrence, I. Ali, J. Viner, C. Sigman, Progress in Cancer Chemoprevention: Development of Diet-Derived Chemopreventive Agents, J. Nutr., 2000 130: 467 
http://jn.nutrition.org/cgi/content/full/130/2/467S
(4) http://www.cancer.org/docroot/ETO/content/ETO_5_3X_Lycopene.asp