Sept. 8, 2003 -- New research shows that chemicals in green and black tea may be able to prevent skin cancer when applied to your skin. Eventually, these chemicals may be put into a lotion that could prevent skin cancer better than sun block alone.
Zigang Dong, MD, and colleagues at the University of Minnesota Hormel Institute in Austin, Minn., tested a solution containing chemicals called polyphenols, extracted from green tea, on live mice who were exposed to ultraviolet (UV) light. They also performed tests on skin cells from mice and humans cultured in the laboratory.
The study results, presented recently at the American Chemical Society annual meeting in New York, show that a protein called JNK-2 appears to be directly related to the development of skin cancer and that this protein can be blocked by the application of polyphenols. After the skin is exposed to UV light, levels of this protein rise and remain high. The researchers think that JNK-2 can cause a molecular chain reaction that makes normal skin cells become cancerous.
The experiments show green tea polyphenols reduce levels of JNK-2 in the skin and block the reaction that causes tumors to form.
Dong says that a lotion -- not a beverage -- would be the ideal way to deliver polyphenols to people's skin. Based on previous research, he says, a person would have to drink as many as ten cups of green tea a day in order to build up enough polyphenol molecules in the skin to produce any benefit.
Sun block works by filtering out UV rays before they penetrate the skin. A lotion containing polyphenols might help prevent skin cancer after exposure to the sun. "Hopefully we can dissolve the polyphenols in the lotion together with a sun block," Dong tells WebMD.
The researchers are already developing such a lotion, but their work is in the very early stages. "We don't have the data yet," Dong says. "We just began to do that."
Dong says he cannot speculate about how long it might take to develop the lotion. At this point, scientists are just beginning to learn what causes cancer, and more than anything, this study sheds light on how skin cancer develops. "Once we know that, we can prevent or treat cancer by targeting the specific genes or proteins," he says.
Nevertheless, Dong says, the study results can't be applied to melanoma -- the deadliest form of skin cancer. That's because no melanoma tumors developed on the mice in this study.
This study comes amid much new research about tea's potential cancer-fighting properties. Other research has shown that drinking green tea may prevent skin cancer, too.
Studies have shown that drinking tea may prevent cancer of the mouth, esophagus, stomach, lung, and prostate, but "when you ask the question whether people drinking more tea tend to have less cancer, then the result is not very clear-cut," C.S. Yang, MD, a cancer researcher at Rutgers University, tells WebMD.
"There are quite a few studies in Japan and China suggesting frequent tea consumption reduces the cancer rate of the stomach, and of the esophagus, and maybe some other sites," he says. "But also many other studies show there's no such beneficial effect. So we're really trying to figure out what's going on here."