According to the World Health Organization, coffee does not cause cancer. Consuming very hot beverages, however, could be a risk.
Coffee was blacklisted as a possible carcinogen in 1991. Now the International Agency for Research on Cancer, an organization within WHO, has reviewed over 1,000 studies on coffee and cancer and concluded that there is "inadequate evidence" that coffee causes cancer.
But the investigation did reveal that the temperature of drinks like coffee and tea could be cause for worry. The report warns that there is evidence that beverages consumed at or above 149 degrees Fahrenheit can cause esophageal cancer.
To be clear, this doesn't mean everyone should throw out their tea or start drinking iced coffee exclusively.
"We are not saying you should avoid hot drinks," IARC press officer Véronique Terrasse said in an email. "Normally the temperature at which coffee or tea is drunk in Western countries is not very hot. Drinking beverages at very high temperatures is more common in certain areas such as South Asia and Latin America or even Eastern Africa, where drinks including mate, coffee or tea are drunk at very hot temperatures."
Specifically, the herbal tea known as mate led the researchers to this conclusion. It's widely drunk in South America and served at over 149 degrees Fahrenheit.
"Mate is not only prepared very hot, but drunk through a metal straw that delivers it directly into the throat," IARC researcher Dana Loomis told the Guardian.
That's the kind of drink the IARC has in mind when it says extremely hot beverages are "probably carcinogenic to humans." Heat damage in the esophagus from the beverages could allow cancer to develop.
As long as you're drinking coffee and tea at a reasonable temperature, you don't need to worry. "But if people are concerned, they can simply wait until their drinks have cooled a little," Terrasse said.