Medications
Both the normal prostate and prostate cancer grow in response to certain hormones like testosterone (T) and dihydrotestosterone (DHT). This observation led researchers to investigate whether drugs that decrease DHT could prevent prostate cancer.
Two major drug trials have been conducted on DHT-reducing medications.
The first, the Prostate Cancer Prevention Trial [1], tested whether the drug finasteride (Proscar) prevented prostate cancer. A total of 18,882 men were randomized to take the drug finasteride or placebo. With long-term follow-up, there was a reduction 30% in the total number of patients in whom prostate cancer was detected. This was balanced by a 17% increase in the number of patients with high-grade prostate cancers detected.
The second, the REDUCE trial [2], tested the effect of the drug dutasteride (Avodart) on preventing prostate cancer in men. A total of 8336 men were randomly assigned to receive dutasteride or placebo. With long-term follow-up, there was a 23% reduced risk of prostate cancer diagnosis with the use of dutasteride. The majority of prostate cancers prevented were low-risk cancers and there was no evidence of a reduction in the risk of high-grade prostate cancers.
The key message from this is that there are currently no drugs that have been found to decrease mortality from prostate cancer. While non-aggressive cancers may be prevented, aggressive cancers were found to occur at the same or a slightly increased rate. Aggressive cancers are much more likely to cause symptoms and death.
Side effects of these drugs are uncommon but include erectile dysfunction, decreased libido, reduced volume of ejaculate, and gynecomastia (growth of male breast tissue).
Other Products
Vitamin C, beta-carotene, and multivitamins do not prevent prostate cancer [4]. Selenium also does not prevent prostate cancer [5]. Patients taking Vitamin E supplements were found in a large study to have a 17% higher risk of prostate cancer [5].
Diet
While no specific change in diet has been found to decrease prostate cancer risk, prostate cancer has been found to be associated with obesity and a high fat diet [6]. Because eating a balanced diet and regular exercise are also important for cardiovascular health and overall well-being, this prevention strategy is highly recommended.
References
1. Thompson, I.M., et al., The influence of finasteride on the development of prostate cancer. N Engl J Med, 2003. 349(3): p. 215-24.
2. Andriole, G.L., et al., Effect of dutasteride on the risk of prostate cancer. N Engl J Med, 2010. 362(13): p. 1192-202.
3. Kramer, B.S., et al., Use of 5alpha-reductase inhibitors for prostate cancer chemoprevention: American Society of Clinical Oncology/American Urological Association 2008 Clinical Practice Guideline. J Urol, 2009. 181(4): p. 1642-57.
4. Gaziano, J.M., et al., Vitamins E and C in the prevention of prostate and total cancer in men: the Physicians’ Health Study II randomized controlled trial. JAMA, 2009. 301(1): p. 52-62.
5. Lippman, S.M., et al., Effect of selenium and vitamin E on risk of prostate cancer and other cancers: the Selenium and Vitamin E Cancer Prevention Trial (SELECT). JAMA, 2009. 301(1): p. 39-51.
6. Campbell, M.F., A.J. Wein, and L.R. Kavoussi, Campbell-Walsh urology / editor-in-chief, Alan J. Wein ; editors, Louis R. Kavoussi … [et al.]. 9th ed. 2007, Philadelphia: W.B. Saunders.