Like your tea or coffee very hot? A study of nearly 1 million adults found a striking cancer link

by · News-Medical

A study of nearly one million UK adults examines how drinking temperature and daily consumption relate to two major forms of esophageal cancer.

Study: Hot Drinks and Oesophageal Cancer: Prospective Analyses in Around 1 Million UK Adults. Image Credit: Krzysztof Winnik / Shutterstock

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In a recent study published in the International Journal of Cancer, researchers investigated associations between hot beverage consumption and participants’ subsequent risk of esophageal cancer. The study pooled data from the Million Women Study (MWS) and the United Kingdom Biobank (UKB) (total n = 977,282) to evaluate how preferred drink temperature and consumption frequency were associated with the risk of specific cancer subtypes.

The study’s findings revealed that participants who preferred their tea or coffee “very hot” were at more than three times the risk of esophageal squamous cell carcinoma (SCC) compared with their “warm” beverage-consuming counterparts. For esophageal adenocarcinoma (AC), preferred drink temperature showed no material association with risk.

While the mechanisms underpinning these observations require further research, the authors conclude that reducing drink temperature could offer a means of SCC prevention. Their modeling estimated that, if the association is causal, switching from “very hot” to “hot” drinks could prevent about 440 SCC cases in the UK each year.

Background

Esophageal cancer is an umbrella term for a spectrum of malignancies that occur in the cells lining the esophageal cavity (food pipe) of the gastrointestinal tract. Data from the World Health Organization’s International Agency for Research on Cancer (WHO-IARC) indicates that in 2020 alone, more than 600,000 new esophageal cancer cases were diagnosed, alongside almost 550,000 deaths, highlighting the global burden of these malignancies and the need to identify modifiable risk factors that could be targeted to reduce their impact.2

Historical studies in South America, the Middle East, and East Asia indicate that the consumption of very hot beverages, typically around 70 degrees Celsius (°C) or higher, is associated with increased esophageal cancer risk. In 2016, the IARC classified drinking very hot beverages, defined as temperatures above 65°C, as Group 2A “probably carcinogenic to humans.”

Studies from Western populations suggest that tea and coffee are commonly consumed at approximately 60°C, raising questions about whether increased risk may also occur below the IARC’s 65°C evaluation threshold and whether consumption frequency contributes independently to cancer risk.

About the study

The present study aimed to address these persistent empirical ambiguities and inform future esophageal cancer policy recommendations by analyzing prospective cohort data from the Million Women Study (MWS; n = 510,112) and the United Kingdom Biobank (UKB; n = 467,170) to investigate links between hot beverage consumption (temperature and frequency) and subsequent esophageal cancer risk. The study focused on two esophageal cancer subtypes: esophageal squamous cell carcinoma (SCC) and esophageal adenocarcinoma (AC).

The combined cohort of 977,282 participants was asked to report their preferred (subjective) drinking temperature (“warm,” “hot,” or “very hot”) and daily consumption frequency (fewer than 6 cups or 6 or more cups per day). These reports were cross-referenced against centrally held National Health Service (NHS) records, which tracked cancer incidence with average follow-up periods of 11.1 years (in UKB) and 14.2 years (in MWS).

The study’s analyses compared SCC and AC risk across preferred drink temperatures, assessed whether consuming 6 or more hot drinks daily was independently associated with risk, and estimated the proportion of SCC cases that might be preventable if the temperature association is causal. A subset of 459,739 MWS participants was also evaluated to assess whether adding milk modified the association between drink temperature and cancer risk.

Study findings

The study identified 1,045 and 1,303 participants who developed SCC and AC, respectively, during the 11-14 years of follow-up. Statistical analyses showed that SCC risk increased with increasing preferred beverage temperature.

With “warm” drinks as the baseline, SCC risk increased as preferred beverage temperature rose. After accounting for how many hot drinks participants consumed each day, those who preferred their drinks “very hot” had more than three times the SCC risk of those who preferred them “warm.” Drink temperature showed no material association with subsequent AC risk.

After accounting for preferred drink temperature, consuming 6 or more hot drinks per day was associated with a 71% higher SCC risk than consuming fewer than 6. The researchers found no statistical evidence that temperature and consumption frequency interacted. For AC, higher daily consumption was associated with only a modest increase in risk.

These associations were also evident among never-smokers and light drinkers. In the MWS subset with milk-use data, the temperature-related association varied little depending on whether women added milk to tea or coffee, addressing the possibility that milk use could explain the temperature findings.

Finally, public health modeling indicated that, assuming a causal association, 14% of UK esophageal SCC cases (about 440 cases annually) could be avoided by switching from “very hot” to “hot” drinks.

Conclusions

The present study is the largest to date and found that drink temperature and hot-drink frequency were independently associated with esophageal SCC risk after adjustment for confounding in two large UK cohorts.

The authors conclude that drink temperature was self-reported rather than directly measured, meaning that the categories “warm,” “hot,” and “very hot” cannot be translated into precise temperatures. The observational design also cannot prove causation, and analyses excluding the first 5 years of follow-up produced similar findings.

While more research is needed to elucidate the mechanisms underlying these observations, the SCC-specific pattern supports thermal injury as a plausible explanation, as these cancers typically arise from squamous cells in the upper two-thirds of the esophagus, which may be particularly susceptible to hot liquids.

For now, the findings support reducing the temperature of very hot tea or coffee before drinking, without specifying an exact cooling time. Lowering drink temperature may offer an accessible, non-invasive strategy for SCC prevention if the observed association is causal.

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