Recent disappointing results in studies of the antioxidant, lycopene, for prostate cancer prevention have made many men question whether it’s still worth loading up on the ketchup and tomato sauce. Although the jury is still out on whether lycopene can protect against prostate cancer, one recent study finds evidence that it might be useful in prostate cancer treatment, potentially slowing down the progression of the disease.
Another antioxidant group of interest for slowing prostate cancer growth is soy isoflavones, a type of naturally occurring estrogen found in plants. In fact, men in certain Asian countries where soy is a dietary staple have a lower incidence of prostate cancer than their counterparts in Western nations.
Positive Results for Lycopene
Investigators at the Barbara Ann Karmanos Cancer Institute at Wayne State University looked at the effects of both lycopene and soy isoflavones on patients with rising prostate specific antigen (PSA) levels-a sign that the cancer has progressed. Patients in the study either took 15 milligrams of lycopene supplements twice a day, or a combination of 15 milligrams of lycopene and 40 milligrams of soy isoflavone twice daily.
Nearly all of the men who took lycopene supplements-35 out of 37 men-saw their PSA levels stabilize, indicating that the disease had slowed. The results are particularly encouraging for patients who are facing treatment with hormone therapy, which often causes such unpleasant side effects as hot flashes, impotence, and osteoporosis. Lycopene, by comparison, has virtually no side effects.
“I think taking lycopene is well worth a try in men with rising PSA levels,” says Ulka Vaishampayan, MD, Chair of the GU Oncology Multidisciplinary Team at the Barbara Ann Karmanos Cancer Institute. “Depending on the rate of PSA rise and the timing of relapse after surgery or radiation, considering lycopene as a component of therapy may be worthwhile.” Men who are taking hormone therapy for prostate cancer that has spread also seemed to benefit from the added lycopene, Dr. Vaishampayan says.
Although scientists don’t know exactly how lycopene acts on prostate cancer cells, they believe it slows down their ability to multiply, in part by inhibiting the receptor for male hormones that feed prostate cancer growth. Lycopene also seems to affect substances in tumors that lead to inflammation, which can cause fatigue and many of the other symptoms cancer patients must endure. Although it hasn’t yet been proven, it is possible that taking lycopene might help relieve cancer symptoms as well as slow its growth, Dr. Vaishampayan says.
As positive as the results with lycopene were in this study, soy seemed to be a bust; taking soy in addition to lycopene didn’t provide any additional benefit. However, Dr. Vaishampayan says hopes for the antioxidant aren’t dashed just yet. Additional testing in larger groups of patients is needed to show whether soy isoflavones might be of any real help in prostate cancer treatment.
Adding Lycopene to Your Diet
What’s the best way to get lycopene? Dr. Vaishampayan suggests taking it in supplement form. “I think through diet alone it is exceedingly hard to get enough lycopene, unless all you’re eating is cooked tomatoes, ketchup, and tomato sauce every day,” she says. Because there is no guideline for how much lycopene to take, she suggests that you check with your doctor before starting on any supplement.
Vaishampayan U, et al. Lycopene and soy isoflavones in the treatment of prostate cancer. Nutrition and Cancer, 2007;59(1):1-7.