"What was particularly marked was that it was the low dose of both lycopene and vitamin E that was the most effective, demonstrating that 'more does not necessarily equal better'. Many pharmacological agents and natural compounds follow a bell-shaped dose response curve, which means that very low or high doses may not work and that there is an optimal dose between the two extremes."
The study showed that the lycopene and vitamin E were effectively taken up in the mice prostates in the same form as they are in humans, said Dr. Limpens.
Dr. Limpens said the findings seem promising, but it was early days yet and the Phase II trial in Germany was designed to verify whether a similar treatment to that used in the mice could alter the course of minimal clinical disease in patients. The lycopene product used (LycoVit), has received the Generally Recognized as Safe (GRAS) status from the United States Food and Drug Administration (FDA) and can be used to fortify foods.
It was too early, said Dr. Limpens, to say whether lycopene and vitamin E could ever be used to prevent prostate cancer in healthy individuals. The first step was to see the results from the studies on men with prostate cancer: changes may, for example, be necessary to optimise the treatment. And before any preventative trials could even be considered it would be essential to verify the compound's potential to really prevent the development of cancer in a mouse model.
"However, our data fit in with the general picture that lycopene and vitamin E may have chemopreventative effects on prostate cancer. Therefore we would certainly recommend that all men regularly eat lycopene and vitamin E-rich foods: for example, all kinds of processed tomato products, papayas, pink grapefruit and w
Contact: Margaret Willson
European Organisation for Research and Treatment of Cancer