Drinking very hot tea linked to oesophageal cancer

Regularly drinking very hot tea, when combined with tobacco or alcohol use, is associated with an increased risk for oesophageal cancer, according to a Chinese study with more than 450 000 participants.1

However, the study, published in Annals of Internal Medicine, found no increased risk of oesophageal cancer in those who drank hot tea but did not smoke or regularly drink alcohol.

Alcohol consumption and tobacco smoking are already well established causes of oesophageal squamous cell cancer. China is among the countries with the highest incidence of oesophageal cancer. Tea drinkers, especially Chinese men, are more likely to smoke and to drink alcohol.

The prospective study included 456 155 people aged between 30 and 79 years from 10 areas across China. The participants in the study were asked how often they drank tea and whether they drank it warm, hot, or boiling hot. They were also asked about smoking habits and whether they drank 15 g of alcohol or more a day—roughly 2 units or a standard glass of wine.

During a median follow-up of 9.2 years there were 1731 new cases of oesophageal cancer. Those who drank high temperature tea, drank alcohol regularly, and smoked had an oesophageal cancer risk five times greater than those who had none of those three habits (hazard ratio 5.01, 95% CI, 4.00 to 6.28). The risk of oesophageal cancer was also increased for those who drank hot or burning hot tea if they either smoked (hazard ratio 1.56, 95% CI, 1.21 to 2.02) or drank excessively (hazard ratio 2.27, 95% CI, 1.16 to 4.45).

The study authors said that drinking very hot tea may damage the epithelium and contribute to oesophageal cancer development. They suggested that abstaining from hot tea might be beneficial for preventing oesophageal cancer in people who drink alcohol excessively or smoke.

In an accompanying editorial, Farin Kamangar from Morgan State University, Baltimore, Maryland, and Neal Freedman from the National Cancer Institutes of Health, said that the study had a rigorous design and careful analysis, but that the findings should be interpreted cautiously as the results are observational. One limitation of the study is that tea temperature was self reported and collected only once at the beginning of the study. “The accumulated literature suggests little risk from hot drinks at temperatures below 65°C. Most people drink beverages at temperatures lower than that threshold; for example, in the US, coffee typically is consumed at around 60°C,” they wrote.

The hypothesis that drinking very hot beverages may cause oesophageal cancer has been around for many years but the link is not firmly established. A smaller population based case control study from Iran, published in The BMJ in 2009, found that drinking hot tea was strongly associated with a higher risk of oesophageal cancer.2

An expert panel assembled by the International Agency for Research on Cancer in 2016 classified drinking very hot beverages as a probable (class 2A) rather than a definite (class 1) carcinogen.