'Very hot' coffee and tea linked to higher cancer risk in nearly 1 million adults

Regularly drinking very hot tea or coffee may raise the risk of a type of esophageal cancer, according to a large study at the University of Oxford.

People who reported drinking beverages "very hot" had about three times the risk of developing oesophageal squamous cell carcinoma (SCC), a type of cancer that begins in the cells lining the esophagus, compared to those who drank warm beverages.

Drinking six or more hot drinks per day was associated with a 71% higher risk of the disease. The same link was not seen for esophageal adenocarcinoma (AC), a type of cancer that develops in the lower part of the esophagus.

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The study included nearly 1 million U.K. adults, making it the largest investigation of its kind to date, according to lead study author Keren Papier, a nutritional epidemiologist at the University of Oxford.

Roughly half of the participants were from the Million Women Study (MWS), who were followed for an average of 14 years, and the other half were from the UK Biobank (UKB), who were followed for 11 years.

"Compared with people who reported drinking their beverages ‘warm,’ those who drank them ‘hot’ had around a 1.7 times higher risk of SCC, while those who drank them ‘very hot’ had around a three times higher risk," Papier told Fox News Digital.

The study was published in the International Journal of Cancer.

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The researchers estimated that, if the observed association reflects a true cause-and-effect relationship, about 14% of SCC cases could potentially be prevented if people drank beverages "hot" rather than "very hot."

The biggest limitation, according to the researchers, is that beverage temperatures were self-reported rather than directly measured. Because people's tolerance for heat differs, participants may have classified similar temperatures differently.

"A limitation of our study was that, although we examined associations by self-reported preferred drink temperature, we did not have data on directly measured drink temperatures, and, therefore, cannot determine how self-reported drink temperature is likely to relate to absolute drink temperature," Papier noted.

"These findings don't mean people need to stop drinking tea or coffee. Just let your drinks cool down a little before drinking them."

An outside cancer specialist agreed the findings are biologically plausible but said they should be interpreted in context.

Dr. Aaron Sasson, chief of surgical oncology and co-director of the gastrointestinal oncology team at Stony Brook Cancer Center in New York, said it’s been known that drinking hot beverages or liquids can be irritating to the esophagus and that it could contribute to the development of esophageal cancer.

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The hotter the liquid, the higher the risk of a "thermal injury," the doctor told Fox News Digital.

"Similar to burning your hand, if you were to get a burn on your hand, you have an increased risk of getting squamous cell carcinoma of the hand, of the skin developing in the burned area," Sasson said. "So, think of that as constantly repeating a burn to the esophagus."

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The doctor reiterated that this study specifically looked at the risk of squamous carcinomas, not adenocarcinomas.

"In the United States, about 85% of all of our cancers are adenocarcinomas. So, the incidence of squamous carcinomas in the esophagus is quite low, just to put it into perspective," he noted.

The lifetime risk of developing squamous cell carcinoma of the esophagus in the U.S. is less than 1%, the doctor said.

Sasson agreed that there was no "objective measurement" of the drinks’ temperature, which poses an unknown variable.

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"If you are a heavy consumer of hot tea or coffee, maybe you'd want to cool it down a little bit," he advised. "But I think, for practical purposes, for most people, [it’s] not the predominant risk factor for squamous cell carcinoma of the esophagus."

Smoking, heavy alcohol use, acid reflux and obesity are among the better-established risk factors for esophageal cancer, Sasson said.

"If you were to limit alcohol consumption and eliminate cigarette smoking, you will have done wonders for your esophagus."