“International research has shown for some time that drinking beverages like mate at very high temperatures, as is typical in South America, is linked to an increased risk of certain oesophageal cancers,” Dr Keren Papier, lead researcher and senior nutritional epidemiologist at Oxford Population Health, was quoted as saying by Cancer Research UK.
“What was less clear was whether this also applied to the temperatures at which hot drinks are usually consumed in Western populations,” Papier said.
Funded by Cancer Research UK, Papier and her team analysed data from almost one million UK adults to investigate whether a similar association exists among people who regularly consume hot drinks.
However, Cancer Research UK stressed that the findings should be viewed in context. Oesophageal SCC is relatively uncommon in the UK, where people have around a 1% lifetime risk of being diagnosed with the disease. Therefore, even if an individual's relative risk increases, the overall risk remains relatively low.
The organisation also said further research is needed to determine exactly how beverage temperature may influence the risk of developing oesophageal SCC.
For the study, Papier’s team analysed data from around 980,000 UK adults participating in the UK Biobank and the Million Women Study.
Participants who consumed hot drinks were asked whether they typically drank them ‘very hot’, ‘hot’ or ‘warm’. Researchers then followed their health records for more than 10 years to determine whether they developed oesophageal SCC.
Compared with people who reported drinking their beverages ‘warm’, those who preferred ‘hot’ drinks had nearly twice the risk of developing oesophageal SCC, while those who drank their beverages ‘very hot’ had about three times the risk.
“This is now the largest study to look at that question in a UK population, where many people drink tea and coffee daily,” Papier was quoted as saying by Cancer Research UK.
“It adds to existing evidence that drinking very hot drinks could increase the risk of oesophageal squamous cell carcinoma.”
The researchers stressed that the study did not find that drinking tea or coffee itself increased the risk of oesophageal SCC. Instead, the association was linked to the temperature at which any hot beverage was consumed.
“While this new research adds to our knowledge around hot drinks and oesophageal SCC risk, the researchers were unable to measure actual drink temperatures given the large number of participants and the duration of the study,” Cancer Research UK said.
Based on research conducted outside the UK, the International Agency for Research on Cancer (IARC) classifies drinking very hot beverages, defined as those above 65°C, as ‘probably carcinogenic’ to humans.
However, this temperature is likely to be higher than that of a typical cup of tea or coffee consumed in the UK. Further research is therefore needed to establish precisely what temperature may increase the risk of oesophageal SCC.
The exact mechanism by which higher beverage temperatures may influence oesophageal cancer risk also remains unclear. However, existing evidence suggests that very hot drinks may damage the lining of the oesophagus, which, over time, could increase the likelihood of cancer developing.