Here's the good news for coffee drinkers: the World Health Organization (WHO) has concluded it doesn't cause cancer. But the bad news is that very hot beverages probaby cause cancer of the esophagus.
“These results suggest that drinking very hot beverages is one probable cause of esophageal cancer and that it is the temperature, rather than the drinks themselves, that appears to be responsible,” said Dr. Christopher Wild, director of the International Agency for Research on Cancer (IARC), a WHO agency.
This is perhaps like saying it's not the fall that kills you but the concrete. But it's an improvement from 25 years ago when the WHO said that coffee was a possible contributor to bladder cancer.
Now the agency says that not only does coffee not contribute to cancer, it may even help reduce the risk of certain cancers, including those of the liver and uterus. The findings are being published today in The Lancet Oncology.
Not too hot
The conclusion that drinking very hot beverages contributes to cancer of the esophagus was based on evidence from epidemiological studies in places such as China, the Islamic Republic of Iran, Turkey, and South America, where tea or maté is traditionally drunk very hot (at about 70 °C), which found that the risk cancer increased with the temperature at which the beverage was drunk.
In experiments involving animals, there was also limited evidence for the carcinogenicity of very hot water.
“Smoking and alcohol drinking are major causes of esophageal cancer, particularly in many high-income countries,” said Wild. “However, the majority of esophageal cancers occur in parts of Asia, South America, and East Africa, where regularly drinking very hot beverages is common and where the reasons for the high incidence of this cancer are not as well understood.”
Esophageal cancer is the eighth most common cause of cancer worldwide and one of the main causes of cancer death, with approximately 400,000 deaths recorded in 2012 (5% of all cancer deaths).
How many of those are related to hot beverages isn't known.
For purposes of the study, “very hot” refers to any beverages consumed at a temperature above 65 °C.