Very hot drinks may increase oesophageal cancer risk – SUCH TV

Researchers found that people who preferred their drinks “very hot” had around three times the risk of oesophageal squamous cell carcinoma (SCC) compared with those who drank them warm, although experts stressed that the overall likelihood of developing the disease remains relatively low.

The study, led by Dr Keren Papier, senior nutritional epidemiologist at the University of Oxford’s population health department, analysed hot-drink habits and health outcomes among 977,282 middle-aged adults.

Participants were asked how they preferred to drink hot beverages, choosing between “very hot”, “hot”, “warm” or “do not drink hot drinks”. Their responses were based on their own perception of temperature rather than precise measurements.

The findings showed that drinking beverages at a “very hot” temperature was associated with a threefold greater risk of oesophageal SCC compared with drinking them warm, after taking consumption frequency into account.

People who described their drinks as “hot” also had around 1.7 times the risk compared with those who preferred warm beverages.

Six or more hot drinks a day also raises risk

The research also found a relationship between the number of hot drinks consumed and SCC risk.

After accounting for drink temperature, consuming six or more hot drinks a day was associated with a 71% higher risk of oesophageal SCC compared with drinking fewer than six hot beverages daily.

However, the study found little association between either drink temperature or frequency and the other major type of oesophageal cancer, known as adenocarcinoma (AC).

The research was published in the International Journal of Cancer and followed participants for around 14 years, providing a long-term assessment of their drinking habits and health.

Researchers combined data from two major UK studies, the UK Biobank and the Million Women Study, making it the largest study to date examining the relationship between hot-drink temperature and oesophageal cancer in a Western population.

The findings also broadly mirror previous research from Asia, Africa, South America and the Middle East, where very hot tea or mate has been linked with an increased risk of oesophageal cancer.

Drinks above 65C considered very hot

The study defines drinks at 65 degrees Celsius or above as “very hot”, although participants did not have their beverages measured at specific temperatures.

Tea poured immediately after a kettle has fully boiled can initially be close to 100C, or 212F. Once poured into a cup, its temperature can fall to around 90-95C, meaning it can still be considerably hotter than the level identified in the research.

Adding milk may lower the temperature somewhat, but a milky tea or coffee can still be hot enough to pose a potential risk if consumed immediately.

A separate study involving 118 young adults found that most participants considered coffee too hot to drink at temperatures of around 70C or higher. One takeaway coffee cup manufacturer recommends temperatures between 49C and 60C for hot coffee, while coffee can be served above 82C when customers request an extra-hot drink.

Why could very hot drinks increase cancer risk?

Experts believe repeated exposure to very hot liquids may damage the cells lining the oesophagus, also known as the food pipe.

The International Agency for Research on Cancer, part of the World Health Organization, classified very hot beverages as “probably carcinogenic to humans” in 2016 and identified them as a probable cause of oesophageal cancer.

The proposed explanation is that repeated heat-related injury to the oesophageal lining may contribute to the development of cancerous changes.

Smoking and alcohol consumption remain major risk factors for oesophageal cancer and are important targets for prevention.

Wait for drinks to cool

Fiona Osgun, head of health information at Cancer Research UK, which funded the study, said there was no need to determine an exact number of minutes for cooling a drink.

She advised people who are concerned about the risk to simply wait until their tea or coffee is comfortable to drink rather than consuming it while it is still very hot.

Cancer Research UK does not believe cafes, coffee shops and restaurants need to start serving tea and coffee at lower temperatures as a result of the findings.

Osgun also stressed that the most important ways to reduce the risk of oesophageal cancer are not smoking and cutting down on alcohol.

More work needed on exact temperatures

Dr Papier said previous international research had already established a link between very hot beverages such as mate and oesophageal cancer.

“What was less clear, was whether this also applied to the temperatures at which hot drinks are usually consumed in Western populations,” she said.

The latest study provides evidence of a similar relationship among people in the UK, where tea and coffee are consumed regularly.

However, Papier said further research is needed to identify the exact drink temperatures associated with the increased risk.

Muy-Teck Teh, professor of molecular oral oncology at Queen Mary University of London, cautioned that the study relied on people’s subjective assessment of how hot their drinks were.

He noted that people who prefer very hot drinks may have differences in temperature sensation or sensitivity in the lining of the mouth and oesophagus. Such biological differences could potentially be related to their underlying susceptibility to SCC.

Because of this, Teh said the possibility that these factors influenced the findings cannot be ruled out, making it difficult to establish causality from the study alone.

Overall risk of oesophageal cancer remains low

Despite the increased relative risk associated with very hot drinks, experts stressed that the overall risk of developing oesophageal cancer remains relatively low.

Squamous cell oesophageal cancer is rare, affecting a few thousand people each year in the UK, while the lifetime risk of being diagnosed with SCC is around 1%.

The researchers estimated that roughly one or two in every 10 oesophageal cancer cases could potentially be avoided if people stopped consuming very hot beverages. One estimate in the study suggested that one in seven UK SCC cases could be avoided if people who currently drink beverages at “very hot” temperatures instead consumed them at temperatures more representative of the “hot” category.

The researchers said an even greater proportion of cases might potentially be prevented by reducing drinking temperatures further, although more research is needed.

Symptoms of oesophageal cancer

Possible symptoms of oesophageal cancer include heartburn, indigestion, pain in the throat or chest and unexplained weight loss.

Experts say people experiencing persistent or concerning symptoms should seek medical advice.

Dr Papier said the latest findings provide clear evidence that the temperature and frequency of hot-drink consumption could be useful targets for preventing oesophageal SCC, while acknowledging that further research is needed to establish the precise temperatures involved.