Tea lovers who take their daily cup scalding hot are exponentially increasing their risk for esophageal cancer if they also drink alcohol every day or if they smoke, say researchers.
A prospective cohort study that followed more than 450,000 people for 9 years provides evidence of a synergistic relationship between drinking hot tea every day, consuming alcohol on a daily basis, and smoking and an increased risk for esophageal cancer.
The study, led by Canqing Yu, PhD, of Peking University Health Science Center, in Beijing, China, was published online February 5 in the Annals of Internal Medicine.
The risk for esophageal cancer was five times higher in individuals who drank very hot tea and drank more than 15 mL of alcohol every day compared to those who drank tea less than once a week and consumed fewer than 15 g of alcohol daily (hazard ratio [HR], 5.00).
In addition, the risk for esophageal cancer was doubled in those who drank piping hot tea each day and smoked tobacco compared to nonsmokers who drank tea only occasionally (HR, 2.03).
“Our findings show a noticeable increase in esophageal cancer risk associated with a combination of high-temperature tea drinking, excessive alcohol consumption, and tobacco smoking,” Dr Yu and colleagues write. “They suggest that abstaining from hot tea might be beneficial for preventing esophageal cancer in persons who drink alcohol excessively or smoke.”
The incidence of esophageal cancer is increasing globally, particularly in men in less developed countries, the investigators point out. In China, where the incidence of esophageal cancer is among the highest in the world, men who drink tea often smoke and drink alcohol.
The analysis included 456,155 participants aged 30 to 79 years who did not have a prior history of cancer. All were enrolled between 2004 and 2008 from five urban and five rural regions of China. At baseline, participants reported the temperature at which they drank tea as well as other lifestyle behaviors, including alcohol consumption and smoking.
During a median follow-up of 9.2 years, 1731 cases of incident esophageal cancer were reported in 1106 men and 625 women.
Although the study showed no increased risk for esophageal cancer in participants who drank only tea every day — scalding or not — the study authors emphasize that “chronic thermal injury to the esophageal mucosa may initiate carcinogenesis.”
Previous research has suggested that damage to the epithelium impairs barrier function, thereby augmenting the risk from other factors, such as excessive alcohol consumption and smoking, they note.
The International Agency for Research on Cancer recently classified drinking beverages hotter than 65° C (149° F) as “probably carcinogenic to humans,” the authors point out. Adding alcohol consumption and smoking to the mix “considerably complicate[s] the association between tea drinking and esophageal cancer risk.”
More prospective studies that directly measure tea temperature are warranted, the study authors say.
In an accompanying editorial, Farin Kamangar, MD, PhD, of Morgan State University, in Baltimore, Maryland, and Neal D. Freedman, PhD, MPH, of the National Cancer Institute at the National Institutes of Health in Bethesda, Maryland, agree that more studies are needed.
The hypothesis that drinking very hot beverages may cause esophageal cancer has been around since the 1930s, they note. “Despite this study’s rigorous design and careful analysis, its results are observational and may still reflect confounding by other factors and chance,” Dr Kamangar and Dr Freedman write.
Tea temperature was assessed by self-report and only at baseline, they point out. Follow-up studies and other cohort studies that have data regarding the temperatures at which tea is consumed “will provide complementary findings when published,” they suggest.
Until then, these results “should be interpreted cautiously,” the editorialists say. They note that tea lovers who are concerned about cancer risk don’t have to give up one of the world’s most popular beverages.
Perhaps those of us who drink hot beverages often should be prudent and wait for the liquid to cool a bit first.
“Perhaps those of us who drink hot beverages often should be prudent and wait for the liquid to cool a bit first. However, the results of this study should not cause people to abandon their favorite beverage. Most people drink their tea and coffee at a temperature that seems unlikely to cause cancer,” the editorialists comment.
To date, studies have provided little evidence of risk to health from hot drinks consumed at temperatures less than 65° C, they point out. In the United States, “coffee typically is consumed at around 60° C (140° F).”
The study was supported by the National Natural Science Foundation of China, the National Key Research and Development Program of China, the Kadoorie Charitable Foundation, the Wellcome Trust (United Kingdom), and the Chinese Ministry of Science and Technology. Dr Yu, the study coauthors, and the editorialists have disclosed no relevant financial relationships.
Ann Intern Med. Published on February 5, 2018.
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