Drinking very hot coffee and tea may significantly increase the risk of oesophageal cancer, with a large UK study finding that people who prefer scalding beverages could face more than three times the risk of developing the disease.
The study, involving nearly 980,000 middle-aged adults, found that the risk was particularly associated with oesophageal squamous cell carcinoma, the most common type of oesophageal cancer globally.
Researchers from the University of Oxford analysed health data from participants in the Million Women Study and UK Biobank.
During follow-up periods averaging 14.2 years and 11.1 years respectively, 2,348 cases of oesophageal cancer were recorded.
The researchers found that people who preferred their drinks hot had almost twice the risk of oesophageal SCC compared with those who preferred warm beverages.
Among those who liked their drinks very hot, the risk was more than three times higher.
The study also found a link between the number of hot drinks consumed and cancer risk.
After accounting for temperature preference, participants who drank six or more hot beverages daily had a 71 per cent higher risk of oesophageal SCC than those who consumed fewer than six.
“This is the largest study to date, and it does really add to the evidence that drinking very hot and hot beverages could increase the risk of this type of cancer,” lead author and senior nutritional epidemiologist at Oxford Population Health, Keren Papier, told CNN.
The International Agency for Research on Cancer classified very hot beverages as probably carcinogenic to humans in 2016, defining “very hot” as drinks served above 65 degrees Celsius or 149 degrees Fahrenheit.
Papier noted that previous research had largely focused on countries in South America, Asia and the Middle East, where hot-drink consumption patterns can differ from those in Britain.
However, the researchers found that adding milk did not alter the cancer risk as long as the beverage remained hot.
“For anyone who does enjoy drinking hot drinks and they’re worried about these findings, really a simple step is to let the drink cool down,” Papier said, adding that people could allow beverages to sit, add milk or cold water, blow on them or take smaller sips.
The researchers, however, acknowledged that they could not establish the exact temperatures of the drinks because participants reported their own perceptions of how hot their beverages were.
As a result, the study could not determine whether the reported categories corresponded to specific temperatures.
Physiologist Muy-Teck Teh, a professor of molecular oral oncology at Queen Mary, University of London, said the findings should be viewed with caution because participants self-reported their preferred temperatures.“the results should be interpreted as robust associations rather than causal proof.”
Epithelial physiologist Ian Johnson, an emeritus fellow at the Quadram Institute in England, said there was a possible biological explanation for the findings because very hot liquids can damage cells lining the oesophagus and trigger inflammation.
“I am inclined to take the research at face value and conclude that it would be prudent for people to consume cooler drinks (less than 65°C) rather than hotter,” Johnson said.
Despite the increased relative risk, oesophageal cancer remains uncommon.
In Britain, the disease accounts for about two per cent of cancer cases, while the lifetime risk of diagnosis is around one per cent.
Smoking remains the biggest risk factor for oesophageal SCC, according to Papier.
The cancer is also more common in parts of Eastern Asia and Southern and Eastern Africa, with alcohol consumption and indoor air pollution identified as other likely contributing factors.
