Green tea drinking habits and esophageal cancer in southern China: a case-control study

To investigate effects of green tea drinking and its temperature on esophageal cancer development.

A 1:2 matched hospital-based case-control study including 150 cases and 300 controls was conducted in southern area of China from June 2004 to May 2010. A self-designed questionnaire was used to collect information on possible risk factors of esophageal cancer, and to assess the tea drinking habit and temperature. Conditional logistic regression was used to calculate odds ratios (ORs) and corresponding 95% confidence intervals (CIs).

We find a significant protective effect of high consumption of green tea on esophageal cancer with low temperature tea (OR=0.79, 95%CI=0.29-0.97). However, drinking tea at a temperature of 70-79° and above 80° was related to greatly elevated risk of esophageal cancer with ORs of 2.21 (1.57-5.53) and 4.74 (2.67-10.51). An agreement was found between reported tea temperature and measured temperature (correlation coefficient =0.62). Further analysis indicated hot tea temperature to be associated with heavy risk of esophageal cancer in former and current smokers and current drinkers (former and current smokers: OR=8.91(1.91-16.77) and 7.33(2.23-12.46), respectively; former and current drinkers: OR=7.58(0.83-9.53) and 6.93(2.01-10.65)).

In the South China context, drinking tea at high temperature significantly increases risk of esophageal cancer, especially in drinkers and smokers.