Those studies – in Europe and the United States – found that people who drank a lot of coffee were less likely to develop cancers of the mouth and throat.

"We saw a protective effect for drinking more than 4 cups of coffee per day," Hashibe said. "This was the 40 percent decrease in risk. We did not observe an association for drinking three cups or less per day."

In an interview via Skype, Mia Hashibe said there was a weak link between cancer risk and drinking decaffeinated coffee, but it wasn't statistically significant. And she and her colleagues found no evidence that drinking tea provided the same protection as drinking coffee. Their research is published in the journal Cancer Epidemiology, Biomarkers & Prevention.

Hashibe says it is not clear how coffee might protect drinkers from certain cancers.

"There are a few chemicals that are known to be antioxidants in coffee. So we are thinking perhaps those compounds are playing some sort of protective role against several cancers."

If those compounds can be isolated, maybe someday you'll be able to take an anti-cancer pill, but for us coffee lovers, the answer may just be another refill.