BACKGROUND: Epidemiological studies suggest that coffee consumption may be inversely associated with risk of endometrial cancer (EC), the most common gynecological malignancy in developed countries. Furthermore, coffee consumption may lower circulating levels of estrogen and insulin, hormones implicated in endometrial carcinogenesis. Antioxidants and other chemopreventive compounds in coffee may have anticarcinogenic effects. Based on available meta-analyses, the World Cancer Research Fund concluded that consumption of coffee probably protects against EC.
OBJECTIVE: Our main aim was to examine the association between coffee consumption and EC risk by combining individual-level data in a pooled analysis. We also sought to evaluate potential effect modification by other risk factors of EC.
PATIENTS AND METHODS: We combined individual-level data from 19 epidemiologic studies (6 cohort, 13 case-control) of 12,159 endometrial cancer cases and 27,479 controls from the Epidemiology of Endometrial Cancer Consortium (E2C2). Logistic regression was used to calculate odds ratios (OR) and their corresponding 95% confidence intervals (CI). All models were adjusted for potential confounders including age, race, body mass index, smoking status, diabetes status, study design and study site.
RESULTS: Coffee drinkers had a lower risk of EC compared to non-coffee drinkers (multi-adjusted OR = 0.87, 95% CI = 0.79,0.95). There was a dose-response relationship between higher coffee consumption and lower risk of EC: compared to non-coffee drinkers, the adjusted pooled ORs for those who drank 1, 2-3 and more than 4 cups/day were 0.90 (95% CI = 0.82,1.00), 0.86 (95% CI = 0.78,0.95), and 0.76 (95% CI = 0.66,0.87), respectively (p for trend < 0.001). The inverse association between coffee consumption and EC risk was stronger in participants with body mass index (BMI) over 25 kg/m2.
CONCLUSION: The results of the largest analysis to date pooling individual-level data further support the potentially beneficial health effects of coffee consumption in relation to EC, especially among females with higher BMI.