Drinking very hot tea or coffee may more than triple the risk of a type of esophageal cancer, according to a new study. The research, involving nearly a million people in the United Kingdom, was published Tuesday in the International Journal of Cancer.
The study found that the risk of esophageal squamous cell carcinoma (SCC) rises with the temperature of hot beverages. People who preferred their drinks “hot” had nearly double the cancer risk compared with those who preferred “warm” drinks, while those who preferred “very hot” drinks had more than triple the risk.
The esophagus is a muscular tube extending from the mouth to the stomach, through which food and drink reach the stomach. Squamous cell carcinoma is one of the most common types of esophageal cancer worldwide.
Researchers at the University of Oxford analysed data from nearly 980,000 middle-aged people in the UK. Participants were asked whether they typically preferred their drinks “very hot,” “hot” or “warm,” and whether they drank fewer than six or six or more hot beverages a day.
Participants were drawn from two large research cohorts, the Million Women Study and the UK Biobank. Over an average follow-up of 14.2 years and 11.1 years respectively, a total of 2,348 cases of esophageal cancer were identified across the two cohorts.
The study found that about half of participants drank six or more hot beverages a day, while about 15 percent said they preferred to drink their beverages very hot.
The research found that not just temperature but quantity was also linked to risk. After accounting for temperature, those who drank six or more hot beverages a day had a 71 percent higher risk of esophageal squamous cell carcinoma compared with those who drank fewer than six.
Lead study author Keren Papier, a senior nutritional epidemiologist at Oxford Population Health, said this is the largest study of its kind conducted so far, and it strengthens the evidence that very hot and hot beverages may increase the risk of this type of cancer.
In 2016, the International Agency for Research on Cancer (IARC) classified beverages hotter than 65 degrees Celsius as a probable carcinogen for humans. However, most previous studies were conducted in South America, Asia and the Middle East. This new study was based on the tea and coffee drinking habits common among people in the UK.
Researchers also found that whether milk was added to the tea or coffee did not significantly change the cancer risk, as long as the drink remained hot.
However, researchers cautioned that participants self-reported information about the temperature of their drinks. The actual temperature was not directly measured, so it is not possible to say with certainty how consistently the categories of “warm,” “hot” or “very hot” corresponded to specific temperatures.
Mui Teck Teh, a professor and physiologist at Queen Mary University of London, said that because the findings rely on participants’ perceived temperature, the results should be viewed as a strong association rather than proof of causation.
Lead author Keren Papier said that for people who enjoy hot beverages and are concerned about the study’s findings, a simple step is to let the drink cool slightly before drinking. Letting it sit for a while, adding milk or cold water, or taking smaller sips can also help lower its temperature.
According to experts cited in the study, very hot liquids may damage and inflame the cells lining the esophagus, which could be a possible explanation for the association found in the research. However, the overall likelihood of developing esophageal cancer remains relatively low. Researchers say smoking remains one of the biggest risk factors for this type of cancer. Esophageal cancer is comparatively more common in East Asia and southern and eastern Africa, where alcohol consumption and indoor air pollution are also considered possible risk factors.