Lycopene and Vitamin E Combination Inhibits Growth of Prostate Tumors

20/04/06 The combination of lycopene and vitamin E suppresses tumor growth in mice by 73 percent and increases survival time by 40 percent. Lycopene alone tends to inhibit tumor growth and to prolong survival time as well, but less effectively (53 percent and 19 percent, respectively). A phase-II clinical trial with prostate cancer patients is ongoing to evaluate the health benefits of lycopene and vitamin E in humans.

BASF has announced the publication of its most recent scientific research study in the field of human nutrition in the upcoming May issue of the Journal of Nutrition. The study entitled „Combined Lycopene and Vitamin E Treatment Suppresses the Growth of PC-346C Human Prostate Cancer Cells in Nude Mice“ was a collaboration with leading researchers in the field of urology at the Erasmus University in Rotterdam, The Netherlands under the lead of Dr. Wytske van Weerden.

Prostate cancer is a major type of malignancy in men. While established risk factors for the disease exist including older age, family history of the disease, and race, there is ongoing search for dietary factors and micronutrients, which help lower the risk of contracting the disease. Epidemiologic studies have repeatedly associated a high intake of lycopene, the major tomato-carotenoid, and vitamin E with reduced prostate cancer risk and these two micronutrients are now among the most promising dietary components with regard to prostate cancer prevention.

BASF investigated how different doses of lycopene and vitamin E affect prostate tumor growth and whether a combination of lycopene and vitamin E exerts additional effects. Furthermore, the possibility to use PSA (prostate-specific antigen) levels in blood, which is an established clinical parameter for the disease, as a marker for tumor growth during lycopene and vitamin E intake was evaluated.

The PC-346C orthotopic mouse model of human prostate cancer, developed by the researchers in Rotterdam, is a useful model to monitor effects of diet on tumor growth. 54 mice were inoculated with prostate cancer cells and three days thereafter the mice were fed with either of the six following diets: lycopene (5 or 50 mg/kg body weight (BW)), vitamin E (5 or 50 mg/kg BW) or a mixture of lycopene and vitamin E (5 mg/kg BW each), or placebo. Tumor growth in prostate and levels of PSA in blood were assessed at regular intervals.

The BASF study shows that combined treatment with lycopene and vitamin E, at 5 mg/kg BW each, is most effective; growth of prostate tumors was suppressed by 73 percent and survival time was increased by 40 percent. There was a trend for 53 percent slower tumor growth and 19 percent increased survival time in the group receiving 5 mg/kg BW lycopene. The other treatments (vitamin E alone or lycopene at 50 mg/kg BW) did not have a significant effect on tumor growth.

Levels of PSA in blood increased with tumor growth in mice receiving placebo treatment. In the group receiving the combination of lycopene and vitamin E, PSA levels tended to be lower. The PSA index, a parameter used to demonstrate selected effects on PSA vs. tumor growth, did not differ between experimental groups indicating that PSA levels were proportional to tumor size regardless of the dietary supplementation with lycopene and vitamin E. Thus, lycopene and vitamin E are unlikely to interfere with PSA measurements, which is important for clinical diagnostics.

The study demonstrates a significant benefit of the combination of lycopene and vitamin E in inhibiting prostate tumor growth. In addition, PSA is corroborated as a marker for tumor burden for this treatment regimen. In order to test the effects of lycopene and vitamin E on tumor growth and PSA levels in humans, an exploratory phase-II prostate cancer trial is currently ongoing.