Note: This story was originally published in 2019 and has been updated.
It seems that almost every dietary habit has at some point been linked to an increased risk of cancer. In recent years, the idea has emerged that drinking very hot beverages like coffee and tea could contribute to esophageal cancer.
We spoke with Memorial Sloan Kettering Cancer Center (MSK) medical oncologist and gastroenterologist Smita Joshi, who cares for people at MSK Monmouth, to learn what is actually known about the topic from research and whether we should be worried about drinking hot beverages.
What gave rise to the idea that hot drinks could increase esophageal cancer risk?
This idea is not new. It goes back to at least the 1930s. The theory has been that hot liquids such as coffee or tea could destroy the inner lining of the esophagus, requiring the cells to continually regenerate. During this process, there is a greater chance that something can go wrong and turn normal cells into cancer cells. A long time ago, animal studies suggested that very, very hot beverages could cause this damage. But this was at higher temperatures than people would usually drink liquids.
What did the 2016 WHO statement and the 2018 and 2019 studies claim?
The WHO has several classifications for cancer risk, and drinking very hot beverages was classified as “probably carcinogenic” to humans. The China study found a higher incidence of esophageal cancer in people who drank more hot tea — but who also drank alcohol every day or smoked.
I think all these conclusions were a bit misleading, at least as they apply to people in the United States and Europe. The type of esophageal cancer that is far more common in the United States is adenocarcinoma. The supposed link with hot beverages is related to an esophageal cancer called squamous cell carcinoma. This type is prevalent in many other parts of the world — China, other parts of Asia, India, South America, and Africa — but is less common in the United States and Europe.
Even for squamous cell carcinoma, the evidence is not clear. The WHO statement was based on a study looking at people who drank a variety of hot teas consumed in these other countries. These populations tend to have more exposure to other factors that raise the risk of cancer, such as smoking, alcohol consumption, cooking over an open fire, and environmental contaminants. The presence of these other factors makes it hard to be certain that hot tea alone was responsible for the increased risk.
The China study had a similar issue. It is plausible that drinking hot beverages might raise esophageal cancer risk if combined with smoking or alcohol consumption. But the study did not find that hot tea alone had that effect. Another problem with the China study was that it asked people to rank for themselves how hot the tea that they drank was. There was no actual measure of temperature. What one person may consider “very hot” may not hold true for someone else. In that sense, it’s not a very scientifically rigorous study.
The Iran study was slightly better. In this case, the temperature of the tea was actually measured rather than estimated by the individuals, which is a strength of the study. It compared esophageal cancer rates in people who drank tea at 60 °C (140 °F) or higher with those who drank it at a lower temperature and in smaller amounts. The weakness of the study is that most people in this region drink tea, and there isn’t a control group available. The higher rate of esophageal cancer might be due to other environmental factors rather than tea temperature.
What’s the most important point that people should remember about hot drinks and esophageal cancer?
There has never been solid evidence that drinking hot liquids alone will increase esophageal cancer risk. At this point, we have only the suggestion that it might make the risk higher in people who smoke or consume alcohol.
If you are still concerned about hot liquids and esophageal cancer risk, you could allow the coffee or tea to cool for a few seconds before drinking it. I would advise people to focus more on factors that are very solidly linked to a higher risk of developing esophageal cancer. For squamous cell, it’s smoking and alcohol. For adenocarcinoma, the most common risk factors are obesity and gastroesophageal reflux disease (GERD).
In short: Cut down on habits that are known risk factors and drink all the reasonably hot liquids you want.
- Studies in China and Iran suggested a link between hot drinks and esophageal cancer.
- There is no evidence that hot liquids alone will increase esophageal cancer risk.
- The cancer in the studies was a different type than typically diagnosed in the U.S. and Europe.
- People should focus more on known risk factors such as smoking, alcohol, and GERD.