Association between coffee drinking and endometrial cancer risk: A meta-analysis

Aim: Coffee drinking is considered as a risk factor of endometrial cancer (EC). Here, we conducted a meta-analysis of observational study to evaluate the relationship between coffee drinking and the risk of EC.

Methods: The MEDLINE and EMBASE databases were searched until July 2018. Pooled relative risks (RRs) with 95% confidence intervals (CIs) were calculated using a random-effects model.

Results: A total of 24 studies (12 case-control and 12 cohort studies) on coffee intake with 9833 incident cases of EC and 699 234 subjects were included in the meta-analysis. The pooled RR of endometrial cancer for the highest versus the lowest categories of coffee intake was 0.71 (95% CI: 0.65-0.77; I² = 14%, p for heterogeneity = 0.26). By study design, the pooled RRs were 0.68 (95% CI: 0.56-0.83) for case-control studies and 0.70 (95% CI: 0.63-0.77) for cohort studies. For different regions, the pooled RRs were 0.74 (95% CI: 0.62-0.88) in Europe, 0.71 (95% CI: 0.64-0.79) in United States/Canada, and 0.40 (95% CI: 0.28-0.57) in Japan. By additional subgroup analysis, a stronger inverse association was shown in caffeinated coffee drinkers (RR 0.66, 95% CI: 0.52-0.83), individuals with the higher body mass index (BMI) (RR 0.65, 95% CI: 0.54-0.79), never smokers (RR 0.68, 95% CI: 0.56-0.84), ever smokers (RR 0.56, 95% CI: 0.45-0.70), and those who never used hormone replacement therapy (HRT) (RR 0.88, 95% CI: 0.79-0.98). The consumption of filtered or boiled coffee showed no significant association.

Conclusions: Increased coffee intake is associated with a reduced risk of EC.