Doctors Set Men Straight on Six Myths About Prostate Cancer
Prostate cancer prevention, diagnosis, and treatment have received a lot attention recently, especially due to the confusion about topics such as PSA testing and when to seek medical treatment. As September is Prostate Cancer Awareness Month, scientists at Fred Hutchinson Cancer Research Center hope to help men separate myth from truth when it comes to foods that may help prevent prostate cancer, risk for getting cancer and PSA testing.
Myth 1 – Tomatoes will prevent prostate cancer.
Lycopene, the nutrient that gives foods such as tomatoes and watermelon their red color, has been associated with reducing the risk of some types of cancer, including prostate cancer. Petri dish studies found that prostate cancer cells “died” in the presence of lycopene equivalent to the levels that would be present in men who ate two to three servings of vegetables daily.
Unfortunately, however, human studies have found very limited evidence to support this. A study published in Cancer Epidemiology, Biomarkers and Prevention reported results based on lycopene in the blood of nearly 3,500 men nationwide and found no association in regards to a reduction in prostate cancer. In 2007, the FDA found limited evidence to support the claim that tomato consumption is linked reduced risk of prostate, ovarian, gastric or pancreatic cancer.
But don’t use this myth to give up eating fruits and vegetables, including tomatoes. Lycopene still has health benefits, including reducing cholesterol, especially LDL (“bad”) cholesterol. Tomatoes are also rich in potassium, which may help reduce blood pressure and the risk of heart and vascular disease.
Myth 2 – Fish Oils (Omega-3 fatty acids) decrease prostate cancer risk.
The association between fish oil and a reduced risk of cancer is based on the anti-inflammatory effects of the omega-3 fatty acids. A preliminary study from UCLA found that a low-fat diet supplemented with fish oil could slow the growth of prostate cancer cells.
Unfortunately, two large, well-designed studies published last year in the American Journal of Epidemiology found that high blood levels of docosahexaenoic acid (DHA) might actually increase the risk of developing certain types of prostate cancer, including an aggressive high-grade form of disease.
Again, though, it is not necessary to avoid fish. Dr. Theodore Brasky PhD of Hutchinson Center’s Cancer Prevention Program, says that the study only reveals that there is no magic bullet – one factor alone will not prevent any type of cancer, including prostate cancer. “Overall, the beneficial effects of eating fish to prevent heart disease outweigh any harm related to prostate cancer risk,” he says.
Myth 3 – Dietary Supplements can prevent prostate cancer.
As mentioned above, supplements of single nutrients – or even combinations of nutrients – do not replace an overall health diet when it comes to preventing cancer. For example, the Selenium and Vitamin E Cancer Prevention Trial (SELECT) failed to show any benefit for prostate cancer from the mineral selenium or vitamin E. In fact, this trial was actually halted because it appeared that vitamin E may actually increase the risk of prostate cancer among healthy men.
But again, remember that dietary supplements may only contain certain forms of a nutrient, when in nature, there are several variations. Vitamin E, for example, has 8 different forms, but only one was studied in the SELECT trial. So don’t avoid foods rich in vitamin E, such as nuts, sunflower seeds, and various vegetable oils. Just remember to keep a balanced, varied diet low in fat and processed foods but rich in natural whole grains, fruits, vegetables, and lean protein sources.
Myth 4 – High testosterone levels increase the risk of prostate cancer.
Elevated testosterone levels may be linked with some health problems, such an increased heart disease risk in older men, but the hypothesis that the hormone is associated with prostate cancer is not valid (unlike estrogen’s strong link to breast cancer risk). A study published in 2008 in the Journal of the National Cancer Institute combined the results from 18 large studies and found no association between blood testosterone concentration and prostate cancer risk.
Myth 5 – Regular PSA screening provides no benefits.
Recently, the US Preventive Services Task Force (USPSTF) suggested that PSA testing may do more harm than good. The teams states that only one in 50 men actually benefits from the treatment that follows a positive PSA result.
“This number, which was released as a preliminary result from the European Randomized Study of Prostate Cancer Screening, is simply incorrect,” says biostatistician Ruth Etzioni, Ph.D., a member of the Hutchinson Center's Public Health Sciences Division. “It suggests a very unfavorable harm-benefit ratio for PSA screening. It implies that for every man whose life is saved by PSA screening, almost 50 are overdiagnosed and overtreated.” This “grossly underestimates” the lives likely to be saved by screening over the long term. “The correct ratio of men diagnosed with PSA testing who are overdiagnosed and overtreated versus men whose lives are saved by treatment long term is more likely to be 10 to one,” she said.
The American Urology Association (AUA) recommends that instead of instructing primary care physicians to discourage men from having a PSA test, doctors should instead focus on how best to educate and counsel patients regarding their own personal prostate cancer risk based on the entirety of their medical assessment and history.
Myth 6 – Prostate cancer does not need to be treated.
This myth has some truth to it. A study from the University of Liverpool found that two-thirds of prostate cancer cases did not require urgent treatment. But men should never attempt to make this decision on their own – especially based on a study that only involved 500 men. Always consult with your doctor before deciding upon treatment courses, discussing both benefits and risks. Doctors do typically know which prostate cancers are less aggressive and slower growing and may not need immediate medical attention, says Dr. Etzioni.
“Men with a low PSA level, a biopsy Gleason score of 6 or lower and very few biopsy samples with cancer are generally considered to be very low risk,” she said. Such newly diagnosed men increasingly are being offered active surveillance – a watchful waiting approach – rather than therapy for their disease, particularly if they are older or have a short life expectancy.
Fred Hutchinson Cancer Research Center (2012, August 22). Prostate cancer: Six things men should know about tomatoes, fish oil, vitamin supplements, testosterone, PSA tests. Retrieved August 24, 2012, from http://www.sciencedaily.com¬