Hot tea and coffee triple the risk of oesophageal cancer, Oxford study shows

A large study conducted by researchers at the University of Oxford shows that the habit of drinking very hot tea or coffee can triple the risk of developing oesophageal cancer. It is the largest study of its kind ever conducted worldwide, according to The Guardian.

The researchers recommend allowing tea and coffee to cool before drinking them, so that they do not cause discomfort when swallowed, in order to reduce the risk of illness.

What the study found

The research showed that both the temperature of the drink and the number of very hot drinks consumed daily influence the risk of developing squamous cell carcinoma (SCC), a form of oesophageal cancer. Hot drinks, however, do not appear to increase the risk of the other main form of oesophageal cancer, adenocarcinoma (AC).

According to the study, published on Wednesday in the International Journal of Cancer, consumption of "very hot" drinks, compared with "warm" ones, was associated with a threefold higher risk of SCC, but no association with AC risk, after adjusting for frequency of consumption.

The researchers also found that, after accounting for drink temperature, consuming six or more hot drinks per day, compared with fewer than six, was associated with a 71% increase in the risk of SCC, whilst the association with AC risk was weaker.

The study was led by Dr Keren Papier, a senior nutritional epidemiologist in the population health department at the University of Oxford.

How the study was conducted

The findings are based on an analysis of hot drink consumption habits among nearly 980,000 people in the United Kingdom — the largest number of participants ever recorded in a study of this type. Those included in the research were followed for 14 years to observe long-term trends in their habits and health.

Participants were asked how they preferred to consume hot drinks, with options including "very hot", "hot", "warm", or "I do not drink hot drinks". The results were based on participants' subjective perception of drink temperature, rather than precise measurements.

Confirmation of earlier findings

The findings for the Western European population confirm similar results previously reported in studies conducted in Asia, Africa, South America, and the Middle East. These showed that consuming tea or maté — a caffeinated herbal drink popular in South America — at a temperature of 70°C or above increases the risk of oesophageal cancer.

The International Agency for Research on Cancer, part of the World Health Organisation, declared as far back as 2016 that very hot drinks are "probably carcinogenic to humans" and represent "a probable cause of oesophageal cancer". The increased risk is thought to arise from thermal damage to the cells lining the oesophagus, also known as the body's "food pipe". Alcohol and smoking also remain major risk factors for this type of cancer.