Cool response to ‘hot tea and cancer’ study

A large study in China concluded that drinking hot tea is associated with a five-fold increased risk for esophageal cancer in people who also drink alcohol and smoke cigarettes (compared with people who consumed none of these three). The findings, which were based on a median of 9.2 years of follow-up in more than 450,000 adult participants, were recently published in Annals of Internal Medicine.

But some experts are pouring cold water on this hot news.

Type of cancer

“The results of this study apply only to the type of esophageal cancer most common in China, squamous cell carcinoma,” noted Jane Green, DPhil, BM BCh, professor of Epidemiology and Codirector of the Cancer Epidemiology Unit, University of Oxford, Oxford, UK.

“In the UK, Europe, and USA, the most common type [of esophageal cancer] is adenocarcinoma, which is associated with different risk factors (mainly, smoking, obesity, and acid reflux),” Dr. Green said. “This study does not tell us whether drinking hot tea is associated with risk of adenocarcinoma of the esophagus.”

How hot is ‘hot’?

The risk for esophageal cancer was greatest among people who drank “burning hot” tea on a daily basis, combined with smoking and drinking 15 g or more of alcohol daily.

Smoking and alcohol aside, “we tend to drink tea at lower temperatures in the West than in China, which is less damaging to the esophagus,” said Andrew Sharrocks, PhD, BSc, professor of Molecular Biology, who researches cellular mechanisms of esophageal cancer at University of Manchester, Manchester, UK. “So, although the study might be relevant to populations in China, it is less relevant in the West in terms of a causative factor.”

The study authors didn’t specify the temperature of “burning hot” tea. However, researchers for the International Agency for Research on Cancer concluded in 2016 that drinking very hot beverages at temperatures above 65° C (149° F) is “probably carcinogenic to humans.”

‘Synergistic’ effect

Still, the increased cancer risk occurred—through a synergistic effect—only in people who drank hot tea and also smoked and drank alcohol, the researchers noted.

“In the absence of smoking and excessive alcohol consumption, daily tea drinking was not associated with an increased risk for esophageal cancer, regardless of tea temperature,” they wrote.

Notably, participants’ tea temperatures weren’t determined by actual measurement, but were reported by participants themselves. Further, the authors wrote, “We did not ask participants about sip size, which together with initial tea temperature, determines intraesophageal temperature; this may have led to differences in subjective perception of temperature.”

“As an aside,” Dr. Sharrocks noted, “I found the paper’s final conclusion somewhat interesting in that it suggests that heavy drinkers of alcohol [and smokers] should abstain from hot tea drinking. Considering the impact of alcohol on health, perhaps that advice should be the other way ’round.”