Web MD -- Drinking coffee may help prevent the most common type of skin cancer.
A new study shows that women who drank more than three cups of coffee per day had a 20% lower risk of developing basal cell carcinoma (BCC) than women who drank less than one cup a month.
Men who drank more than three cups of coffee benefited from a 9% reduction in risk of this type of skin cancer.
Drinking decaffeinated coffee did not have any effect on skin cancer risk, which leads researchers to suspect caffeine is the key ingredient.
"It is likely that caffeine has a protective effect," researcher Fengju Song, PhD, postdoctoral fellow in dermatology at Brigham and Women's Hospital and Harvard Medical School, says in an email. "BCC risk was inversely associated with caffeine."
But before you go out and pour yourself another cup of joe, experts say there are better things you can do to reduce your risk of skin cancer.
"This is yet another study that says there is some benefit in terms of skin cancer for drinking caffeinated beverages," says Paul Nghiem, MD, PhD, associate professor at the Fred Hutchinson Cancer Research Center and University of Washington. "And if you do so, it is another reason to enjoy them. But it is a pretty small effect compared to known things, like getting a cancer detected and cut out early, avoiding sunburns, etc."
Researchers say it's the first large, prospective study to look at the effect of coffee drinking on three different types of skin cancer: basal cell carcinoma, squamous cell carcinoma (SCC), and melanoma.
Basal cell carcinoma is the most common type of skin cancer and accounts for about 90% of skin cancers.
Previous studies have suggested coffee drinking may help protect against non-melanoma skin cancers, but the results have been inconsistent and mostly in animals or laboratory studies.
The study was presented at the American Academy of Cancer Research meeting this week in Boston. Researchers looked at the effects of coffee drinking on skin cancer risk in more than 110,000 people who participated in the Nurses' Health Study and Health Professionals Follow-Up Study.
The participants were followed for an average of 22 to 24 years. During this period, 25,480 cases of skin cancer were reported, including 22,786 basal cell carcinomas, 1,953 squamous cell carcinomas, and 741 melanomas.
The results showed that the amount of caffeinated coffee people drank was associated with the risk of basal cell carcinoma but not other types of skin cancer.
For example, compared with those who drank the least caffeinated coffee, women who drank the most coffee had an 18% lower risk of basal cell carcinoma, and men had a 13% lower risk.
"It's a very interesting study. It's the first one that has implicated basal cell carcinoma reduction in coffee drinkers," says Allan Conney, PhD, director of the Susan Lehman Cullman Laboratory for Cancer Research at Rutgers, The State University of New Jersey. "I am surprised to see that there was no effect on squamous cell carcinomas, which the animal models would have predicted."
Conney says the biology of these types of skin cancer is different and might explain why caffeine appears to have a protective effect against some types of skin cancer and not others.
Nghiem, who has worked with Conney on mouse studies of caffeine and skin cancer, says caffeine appears to help prevent skin cancer by killing the small number of precancerous cells that are damaged by sunlight and are in the process of dividing at the time of exposure.
"Those are cells that have gone rogue and need to be eliminated. Caffeine helps in eliminating those cells," Nghiem tells WebMD.
But he says a dose of caffeine may be much more effective in preventing skin cancer on a day in which you are headed to the beach rather than any cumulative effects of overall coffee drinking.
"Drinking coffee on a gray and rainy day is probably not very relevant," says Nghiem. "What we are testing now is what happens when you drink coffee on a day you go out and get sun."
He says they are also looking into whether caffeine should be added to sunscreen to increase its effectiveness against skin cancer.