Scientists have linked very hot drinks with an increased risk of one type of esophageal cancer

Scientists from the University of Oxford found that fans of very hot drinks are more likely to experience squamous cell carcinoma of the esophagus. The results of the work were published in the International Journal of Cancer, reports the correspondent of the agency “Minsk-Novosti” with reference to the publication “Medical Bulletin”.

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This is not the first such study, writes the Medical Journal. Previously, a similar pattern was found in Asia, Africa, South America and the Middle East, but in smaller samples. In 2016, the International Agency for Research on Cancer (IARC) at WHO classified beverages hotter than 65 °C as “probably carcinogenic to humans.”.

The new study covered almost 977.3 thousand people: more than 510.1 thousand women (average age – 64.5 years) from the British project Million Women Study and about 467.2 thousand participants (average age – 56.4 years) from the UK Biobank. The volunteers were asked whether they preferred warm, hot or very hot drinks, and how many cups of tea and coffee they drank daily. Medical data were tracked for an average of 14.2 years and 11.1 years, respectively. Factors such as smoking, alcohol and weight changes were also taken into account.

During the follow-up, esophageal cancer was diagnosed in 2,348 people (about one case per 416 participants). 1,303 of them had adenocarcinoma, 1,045 had squamous cell carcinoma (about 1 in 935 people over 11-14 years).

Those who preferred very hot drinks had a three times higher risk of squamous cell carcinoma than those who preferred warm drinks (relative risk of 3.17). The real range is estimated to be 2.5 to 4 times. The pattern persisted even after adjusting for the number of drinks consumed: the risk increased with the temperature group.

With adenocarcinoma, the picture is different: very hot drinks did not have a noticeable effect (risk ratio of 0.92), and estimates ranged from a 24 percent reduction in risk to a 12 percent increase.

It matters and the quantity. Those who drank six or more cups of hot beverages a day had a 71% higher risk of squamous cell carcinoma than those limited to a lower number (risk ratio 1.71). For adenocarcinoma, the association was weaker: an increase of about 19%.

The authors of the study estimate that approximately 14 percent of adult squamous cell esophageal cancer cases would have been avoided if fans of very hot drinks reduced their temperature to just “hot.” Further cooling would have prevented more cases.

The findings are consistent with earlier findings from Asia and South America, which traditionally drink very hot tea or mate. Temperatures above 70°C have already been linked to an increased risk of esophageal cancer.

The strength of the study is scale: nearly a million people have been followed for at least 10 years. However, this is still observational work that shows the link but does not prove the cause or explain the mechanism. Scientists suggest that regular exposure to high temperatures causes microtraumas and damages cells of the esophageal mucosa, which over time can increase cancer risk.