Coffee consumption and the risk of endometrial cancer: Evidence from a case-control study of female hormone-related cancers in Japan.

Coffee has become a popular beverage worldwide. Caffeine, a major ingredient of coffee, has been proposed to have a favorable affect on the modulation of circulating estrogen levels and therefore may be of importance in developments on hormone-related cancers. However, epidemiological evidence is limited and inconsistent. We examined the relationship between intake of coffee and hormone-related cancer risk among Japanese women using data from the hospital-based epidemiological research program at Aichi Cancer Center (HERPACC). In total, 2122 breast, 229 endometrial and 166 ovarian cancer cases were included, and 12 425 women, confirmed as free of cancer, were recruited as the control group. Odds ratios (OR) and 95% confidence intervals (95% CI) were determined by multiple logistic regression analysis. A statistically significant inverse association between risk of endometrial cancer and coffee consumption was noted in Japanese women, with no clear association evident for breast and ovarian cancer risk. Compared to non-drinker, the OR of daily drinking of 1-2 cups and 3 or more cups per day for endometrial cancer were 0.64 (95% CI: 0.43-0.94) and 0.41 (95% CI: 0.19-0.87), respectively, and the linear trend was also statistically significant (P < 0.01). However, there was no statistically significant association between caffeine intake and endometrial cancer. In summary, the results of the present study suggest that coffee consumption reduces the risk of endometrial cancer in Japanese subjects. Given the scarcity of studies of coffee intake and endometrial cancer and other hormone-dependent cancer risk, additional investigations are warranted.