Coffee's anti-cancer link explained: study

The findings indicate that moderate caffeine drinking, or perhaps even applying coffee to the skin, could be useful in warding off non-melanoma cancer, the most commonly diagnosed of all skin cancers.

Using mice that had been genetically altered to suppress a protein called ATR, researchers showed that the mice were able to fend off cancer even when exposed to ultraviolet light.

Previous studies have suggested that drinking a cup of caffeinated coffee per day has the effect of suppressing ATR and triggering the die-off of cells harmed by UV rays.

The altered mice eventually did develop cancer, but three weeks later than normal mice.

After 19 weeks of ultraviolet light exposure, the engineered mice showed 69 percent fewer tumors and four times fewer invasive tumors than the control group.

However, the protective effects only went so far. After 34 weeks of UV exposure, all the mice developed tumors.

"Eventually, if you treat them long enough, the mice will develop cancer so it is not 100 percent protection forever," Allan Coffey, one of the study's authors, told AFP.

"Really, with almost any carcinogen, eventually all the animals will develop tumors."

Coffey and his team were able to confirm their hypothesis that caffeine -- when consumed or applied to the skin -- works by inhibiting ATR. Now they say more studies are needed to see how it may work on humans.

"We want to see whether caffeine has an effect in people when you give it topically," he said.

Skin cancer is the most prevalent cancer in the United States, with more than one million new cases each year, according to the National Cancer Institute.

Non-melanoma types of skin cancer, including basal cell and squamous cell types, are the most commonly diagnosed and are often treatable if detected early.