Drinking piping hot tea or coffee could almost double the risk of developing cancer of the oesophagus, warns new research.
Scalding water damages the lining of the mouth and throat which can fuel tumours, say scientists.
A study of more than 50,000 people found those who drank their cuppa at a temperature of 60 C (140 F) were 90% more likely to be struck down.
This rose to 2.4 times among those who regularly drank it at 75 C (167F).
The researchers said their findings based on tea will apply to other beverages including coffee or hot chocolate.
Lead author Dr Farhad Islami, from the American Cancer Society, said: “Many people enjoy drinking tea, coffee, or other hot beverages.
“However, according to our report, drinking very hot tea can increase the risk of esophageal cancer, and it is therefore advisable to wait until hot beverages cool down before drinking.”
Published in the International Journal of Cancer, the study looked at the drinking habits of people aged 40 to 75 who lived in north-eastern Iran.
During a follow-up period from 2004 to 2017, 317 new cases of oesophageal cancer – also known as cancer of the food pipe – were identified.
It affects mainly in people in their 60s and 70s. Men are more at risk than women.
Symptoms can include difficulties in swallowing, persistent indigestion or heartburn , bringing up food soon after eating, a loss of appetite and weight loss or pain in the upper tummy, chest or back.
This is the first study to confirm the link between hot drinks and the disease it by following so many people for such a long period.
Researchers collected information on how long the participants waited between tea being poured and drunk and if they liked it warm, lukewarm, hot or very hot.
They also prepared two fresh cups of tea at the time – one for the participant and the other for the interviewer – to measure the temperature using a digital thermometer.
When the drink was 75 C participants were asked to sip the tea. If it was their usual tea drinking temperature or they usually drank higher temperature tea, it was recorded.
Georgina Hill, health information officer at Cancer Research UK, said: “This study adds to the evidence that having drinks hotter than 60 degrees may increase the risk of oesophageal cancer, but most people in the UK don’t drink their tea at such high temperatures.
“As long you’re letting your tea cool down a bit before you drink it, or adding cold milk, you’re unlikely to be raising your cancer risk – and not smoking, keeping a healthy weight and cutting down on alcohol will do much more to stack the odds in your favour.”
In 2016, the International Agency for Research on Cancer – the cancer agency of the World Health Organisation – classified drinking very hot beverages above 65C as a probable carcinogen.
The IARC examined studies that mostly looked at mate, a type of tea that is traditionally drunk at very hot temperatures, mainly in South America, Asia, and Africa.
They said it was the temperature rather than the type of drink that was associated with cancer.
The new study did not mention mate but examined tea.