Caffeine may prevent skin cancer because it disrupts a protein called ATR-Chkl that could cause the damaged cells become cancerous, says a leading U.S. researcher.

Dr. Paul Nghiem, an associate professor of dermatology at the University of Washington in Seattle, said, "We have found what we believe to be the mechanism by which caffeine is associated with decreased skin cancer."

For the study, Nghiem's team looked at caffeine's effect on human skin cells in a laboratory that had been exposed to ultraviolet radiation. They found that in cells damaged by UV rays, caffeine interrupted ATR-Chk1, which caused the damaged cells to self-destruct. "Caffeine has no effect on undamaged cells," Nghiem said.

ATR is essential to damaged cells that are growing rapidly, Nghiem said, and caffeine specifically targets damaged cells that can become cancerous. "Caffeine more than doubles the number of damaged cells that will die normally after a given dose of UV," he said.

"This is a biological mechanism that explains what we have been seeing for many years from the oral intake of caffeine," he added.

But, Nghiem added, people shouldn't increase the amount of coffee or tea they drink to prevent skin cancer. "You are talking a lot of cups for a lot of years for a relatively small effect," he said. "But if you like it, it's another reason to drink it."

Nghiem has also been experimenting with applying caffeine directly to the skin. "It suppresses skin cancer development by as much as 72 percent in mice, and human studies are moving ahead slowly," he said.

It's possible that topical caffeine preparations might one day be used to help prevent skin cancer, Nghiem said. "Caffeine is both a sunscreen and it deletes damaged cells," he said. "It may well make sense to put it into a sunscreen preparation."

Dr. Robin Ashinoff, a dermatologist and clinical associate professor of dermatology at New York University's Langone Medical Center, however, thinks these findings need to be verified before they can have any clinical application.

(Agencies via Xinhua February 28, 2009)