Lycopene plus vitamin E slows human prostate tumor growth in mice

In a mouse model of human prostate cancer, low doses of lycopene combined with low doses of vitamin E significantly inhibit tumor growth and reduce plasma prostate specific antigen (PSA) concentrations accordingly.

Reporting the findings at a cancer conference in Geneva, Switzerland on Thursday, Dr. Jacqueline Limpens said these findings fit with the general picture that lycopene and vitamin E may have anticancer effects in prostate cancer.”Several epidemiological studies have shown that there is an inverse relationship between tomato consumption, lycopene intake and lycopene serum levels and the incidence of advanced prostate cancer,” she said.”It’s not only beneficial in prevention,” she added, “but in a short 3-week intervention trial in patients with prostate cancer, intake of lycopene-rich tomato extract led to a decline in PSA.” Vitamin E intake has also been tied to lower prostate cancer risk but data are conflicting on this front.In the current study, Dr. Limpens and colleagues injected human prostate cancer cells into the prostate of athymic nude mice. Beginning three days after tumor inoculation, the animals were given daily supplementation with low- or high-dose lycopene (5 or 50 mg/kg body weight), low- or high-dose vitamin E (5 or 50 mg/kg), a mix of low-dose lycopene/vitamin E (5 mg/kg each), or water placebo.Low-dose lycopene alone significantly suppressed prostate cancer growth by 53% at day 42 and extended the tumor doubling time similarly. All other single treatments failed to show any significant tumor-inhibiting effects.The combination of low-dose lycopene and vitamin E was “by far the most effective,” suppressing prostate tumor growth by 73% at day 42, Dr. Limpens reported.”Most importantly,” she said, PSA values and PSA doubling times matched the tumor responses in all experimental groups. This supports the use of PSA as a useful surrogate marker for the effects of these nutrients in ongoing prostate cancer clinical trials, she said.Dr. Limpens, from Erasmus Medical Center in Rotterdam, the Netherlands, presented the findings at the Symposium on Molecular Targets and Cancer, sponsored by the European Organization for Research and Treatment of Cancer (EORTC), the U.S. National Cancer Institute (NCI) and the American Association for Cancer Research (AACR).(Source: Reuters Health News: Megan Rauscher: Oncolink: October 2004.)