Caffeine and exercise may help prevent skin cancer

Having your morning coffee and hitting the gym may be a prescription for staving off skin cancer, U.S. researchers have found.

A study on mice found that the equivalent of drinking two cups of coffee and then exercising dramatically reduced the number of sun-damaged cells that can lead to cancer. In the experiments, one group of hairless mice drank caffeinated water, another exercised on arunning wheel and a third group drank and ran on the wheel. All three groups were exposed to cell damaging UVB radiation, the equivalent of spending 15-30 minutes outdoors at midday.

Cell death or apoptosis,the body'sway of killing off DNA-damaged cells,was observed in all three groups. But the group of mice that drank caffeine and exercised had a 400 per cent increase in cell death, versus 120 per cent for the exercisers and 95 per cent increase for the caffeine drinkers.

The studies, conducted in the Susan Lehman Cullman Laboratory for Cancer Research at Rutgers' Ernest Mario School of Pharmacy, will appear in the July 31 Proceedings of the National Academy of Sciences.

They follow previous studies that showed both caffeine and exercise in isolation inhibited ultravioletlight-induced skin cancer. Caffeine has been linked to a reduction in liver cancer and breast cancer, and exercise has been shown to reduce the risk of colon cancer, among others.

"Because of those studies, we looked at the combination and found that we were getting a very dramatic effect in ultraviolet light-induced apoptosis," Allan Conney, director of Rutgers' Cullman Laboratory and one of the paper’s authors, told CBC News.

Conney said that scientists don't know why the combined effect of caffeine and exercise is much greater in preventing skin cancer than just drinking caffeinated beveragesor exercising. He says there are some theories that both candecrease tissue fat, but more research is needed in identifying the mechanisms that come into play.

"I think it's important to do the human studies," Conney said. One of theareas scientists will be exploring is how much exercise will humans have to do to get the protective effect, he said, noting that the mice in the study groups ran about 3.2 km per day. "That needs to be quantified in people— those who do moderate exercise, light exercise—to see if there's a difference in risk in different populations."

The occurrence of skin cancer has been increasing in Canada at a fairly constant rate over the past 30 years, according to Health Canada. In 2005, there were roughly 78,000 new cases of basal and squamous cell carcinomas reported and about 4,400 new cases of malignant melanomas.