BERKELEY, CA (UroToday.com) - Family history is one of the most important risk factors for prostate cancer.
Despite years of research, however, the molecular basis for inherited prostate cancer has not been fully elucidated. Men with one or more first degree relatives who have been diagnosed with prostate cancer are at a 2-3 fold increased risk of the disease. Given this risk, men with a brother affected by prostate cancer are an important target population for chemopreventive strategies.
Recent studies have investigated the role of vitamins, supplements, and herbs that may reduce risk of prostate cancer, however the results of these studies have been inconsistent. Although previous studies supported the use of selenium and vitamin E in reducing the risk of prostate cancer, recent results from the Selenium and Vitamin E Cancer Prevention Trial (SELECT)1 show no effect of selenium or vitamin E on reducing prostate cancer incidence. Similarly saw palmetto supplementation has not been shown to reduce prostate cancer risk despite its symptomatic relief in men with benign prostatic hypertrophy. Thus, it is important to understand the patterns of vitamin and supplement use by men at an increased risk for prostate cancer as a means of elucidating the degree of concern within this population and how chemopreventive approaches should be tailored to include supplements with proven benefit for prostate cancer risk reduction.
In the current study, we describe the use of vitamins and supplements in a cohort of men at increased risk of prostate cancer based on their family history of disease. Correlates of use and motivating factors for use of vitamins and supplements were also examined in this cohort. All study subjects were participants in the University of Michigan Prostate Cancer Genetics Project (PCGP), a family-based cohort study of inherited forms of prostate cancer. Individuals from the PCGP were asked to contact an unaffected brother to participate in the study. Participants self-reported their use of medications, vitamins, and supplements aimed at prostate-specific or overall health.
Our results demonstrate that nearly 60% of men with a family history of prostate cancer are currently using a vitamin or supplement. Approximately one third of men reported using a vitamin or supplement implicated in prostate cancer prevention or prostate health including green tea, magnesium, saw palmetto, selenium, soy, vitamins A, C, and E, and zinc. Other than multivitamins, vitamin C, vitamin E, and saw palmetto were among the most used vitamins and supplements. Increasing age at the time of survey and younger birth order (as compared to an affected brother) were significantly associated with use of vitamins and supplements. The most common source of information on the use of vitamins or supplements for cancer prevention were family members and articles, while only 3.5% of men cited their urologist as a source of information.
Despite conflicting evidence published on the associations between vitamin and supplement use and prostate cancer risk, nearly 100 studies involving dietary supplementation and prostate cancer are ongoing and registered with clinicaltrials.gov.2 The 5-alpha reductase inhibitors (5-ARIs) finasteride and dutasteride are the only chemopreventive agents with demonstrated clinical benefit in the reduction of prostate cancer risk yet very few patients on our study reported use of these agents. This is likely due to the concern that 5-ARIs have been associated with a slight but statistically significant increased risk for high-grade prostate cancer, which could offset the potential benefit of overall risk reduction.3
Given the few established risk factors for prostate cancer, men with a family history of prostate cancer represent an ideal target population for the study of chemopreventive interventions. The high rates of vitamin and supplement usage within our study suggests that these men have a high degree of concern for their risk of prostate cancer and are motivated to adopt chemopreventive strategies. Furthermore, recent media attention regarding updated analyses of the SELECT trial and the potentially harmful impact of vitamin E on prostate cancer incidence will bring this issue to the attention of men across the country.4 Physicians should be aware of their patients’ interest in strategies to reduce prostate cancer risk among men with a family history of disease and engage their patients in a discussion of evidence-based information regarding the risks and benefits of vitamins, supplements, and prescription medications for chemoprevention.
References:
- Lippman SM, Klein EA, Goodman PJ, 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 Jan 7;301(1):39-51.
- National Institutes of Health State-of-the-Science Panel. National Institutes of Health State-of-the-Science conference statement: multivitamin/mineral supplements and chronic disease prevention. 2006. http://consensus.nih.gov/2006/multivitaminstatement.pdf. Accessed June 27, 2011.
- Andriole GL, Bostwick DG, Brawley OW, et al. Effect of dutasteride on the risk of prostate cancer. N Engl J Med. 2010;362: 1192-1202
- Klein EA, Thompson IM Jr, Tangen CM, et al. Vitamin E and the risk of prostate cancer: the Selenium and Vitamin E Cancer Prevention Trial (SELECT). JAMA. 2011 Oct 12;306(14):1549-56.
Written by:
Christina M. Bauer, Miriam B. Ishak and Kathleen A. Cooney as part of Beyond the Abstract on UroToday.com. This initiative offers a method of publishing for the professional urology community. Authors are given an opportunity to expand on the circumstances, limitations etc... of their research by referencing the published abstract.
UroToday.com Prostate Cancer Section