Caffeine 'may cure skin cancer'

The study used caffeine from green tea

Caffeine could one day be used to cure skin cancer, scientists believe.

Researchers in the United States have found that caffeine combined with an extract from green tea can kill the disease in mice.

They have discovered that rubbing both substances onto the skin of mice stopped the cancer from spreading and killed all tumours.

We may have found a safe and effective way of preventing skin cancer

Allan Conney, Rutgers University

The researchers have said more studies are needed to find out whether the technique could also benefit humans.

Allan Conney and colleagues at Rutgers University in New Jersey studied a special strain of hairless mice over 20 weeks.

Exposed to light

The mice had been exposed to ultraviolet B light twice a week during this period, which put them at risk of skin cancer.

After stopping the exposures, the researchers applied two components of green tea - caffeine and an extract called epigallocatechin gallate (EGCG) - to the mice's skin.

They found that both substances had successfully tackled cancer. However, they believe that caffeine may be more effective because it is more stable chemically than EGCG.

Mr Conney said: "We may have found a safe and effective way of preventing skin cancer."

The researchers found that both caffeine and ECCG killed cancer cells without damaging any surrounding skin.

"The discovery of this selectivity was very exciting to us," said Mr Conney.

"Also in our study, it didn't matter if the tumours were benign or malignant. Cells in both were killed while leaving the normal cells alone."

Previous studies have suggested that drinking caffeine can also help to fight skin cancer. However, the dose required is very high and may not be suitable for human consumption.

"Whether you can give enough orally to be effective in humans is not known," Mr Conney said.

"Whether people could ingest that amount without becoming hyperactive is also a real question mark."

Further study

The researchers said they were planning to carry out trials to see if caffeine had a similar impact on humans with skin cancer.

However, they said such a treatment remained a long way off.

"For now, if you are a mouse, it would be terrific. In people, we just don't know yet," said Mr Conney.

The study is published in the journal Proceedings of the National Academy of Sciences.