Piping hot drinks shown by WHO to increase risk of oesophageal cancer.

Smoking and alcohol drinking are major causes of oesophageal cancer, particularly in many high-income countries. However, the majority of oesophageal 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. Now, an international study from researchers at the WHO’s International Agency for Research shows that drinking piping hot coffee, tea and the caffeine-infused beverage yerba mate, probably causes cancer. The team states that beverages surpassing 149 degrees Fahrenheit or 65 degrees Celsius may increase the risk of tumours in the esophagus, which resides in the chest area below the throat.

Previous studies show that oesophageal 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, and 5% of all cancer deaths. The proportion of oesophageal cancer cases that may be linked to drinking very hot beverages is not known. The current study investigates whether drinking coffee, mate or other very hot beverages causes cancer.

The current study scoured more than 1,000 studies on over 20 different types of cancer. Results show that drinking any beverage hotter than 149 degrees Fahrenheit is probably carcinogenetic to humans, placing scalding hot drinks in the same category as DDT, frying food at high temperatures, consumption of red meat and the human papillomavirus.

Data findings show no conclusive evidence for a carcinogenic effect of drinking coffee, however, it was observed that drinking very hot beverages probably causes cancer of the oesophagus in humans. Results also show that drinking yerba mate, which is common practice in certain countries in South America, including Argentina, Uruguay and Paraguay, at low temperatures is not carcinogenic. The group estimate that a cup of coffee a day decreases the risk of liver cancer by 15%; in other words, the scientists are giving coffee lovers a free pass to drink as much coffee as their bladders can handle.

The team surmise that their findings suggest that drinking very hot beverages is one probable cause of oesophageal cancer and that it is the temperature, rather than the drinks themselves, that appears to be responsible. For the future, the researchers state that the large body of evidence led to the re-evaluation of the carcinogenicity of coffee drinking, previously classified as possibly carcinogenic to humans (Group 2B) by IARC in 1991, to safe for consumption as long as the non-alcoholic beverages are not scalding hot.

Source: Keck Medicine of USC