Caffeine intake has been inconsistently associated with the risk of ovarian cancer in previous studies. The measure of caffeine in these studies has not always distinguished between caffeinated and decaffeinated sources, and the time for which intake was assessed was often for late adulthood and thus may have excluded the etiologic window. We investigated lifetime caffeine intake from caffeinated coffee, black tea, green tea and cola sodas in relation to ovarian cancer risk.
Among 497 cases and 904 controls in a population-based case-control study in Montreal, Canada, lifetime intake of caffeinated coffee, black tea, green tea and cola sodas was assessed and used to calculate lifetime total intake of caffeine. Unconditional multivariable logistic regression was used to estimate odds ratios (ORs) with 95% confidence intervals (CIs) for the association between caffeine intake and ovarian cancer risk overall, as well as by menopausal status. Multivariable polytomous logistic regression was used to estimate the associations for invasive and borderline ovarian cancers separately.
Almost all participants (98.4% of cases and 97.5% of controls) had consumed caffeine in their lifetime. The mean (standard deviation) daily consumption of caffeine over the lifetime was of 117 (89) mg/day among cases and 120 (118) mg/day among controls. The OR (95% CI) of ovarian cancer for the highest versus lowest quartile of lifetime caffeine intake was 1.17 (0.83–1.64). According to menopausal status, the OR (95% CI) was 1.56 (0.85–2.86) for premenopausal women and 0.94 (0.66–1.34) for postmenopausal women, comparing the highest to lowest tertiles of intake. Associations for invasive and borderline ovarian cancers separately were similar to that observed for ovarian cancer overall.
Lifetime caffeine intake was not strongly associated with ovarian cancer risk. A difference in relationship by menopausal status is possible.
Caffeine intake over the lifetime and ovarian cancer risk was examined
The association was examined among all women, and according to menopausal status
Caffeine intake was not associated with ovarian cancer risk overall
The findings hinted at an increased risk among premenopausal women
Additional research is needed to confirm a possible difference by menopausal status
Ovarian cancer, the most deadly of the gynecologic cancers , is the eighth most common cancer worldwide with an increasing incidence in several countries . Prognosis is poor and modalities to detect disease early in the general population are limited, thus, primary prevention is important, and can be improved with knowledge of modifiable risk factors. Caffeine is one such potential factor, which is found in a variety of foods and beverages, most frequently in coffees, teas, and cola sodas . Approximately 90% of the North American adult population consume caffeinated beverages daily, making this a highly prevalent exposure . In two expert evaluations carried out by the International Agency for Research on Cancer, the evidence to classify the carcinogenicity of caffeine and the caffeine-containing beverages coffee and maté was insufficient. Caffeine may contribute to ovarian cancer risk through an influence on the cell cycle , DNA repair or on levels of gonadotropins or estrogen . On the other hand, caffeine may play a preventive role through its antioxidant properties and ability to interfere with proinflammatory processes .
While several studies have examined intake of coffee and tea in relation to ovarian cancer risk, only twelve have assessed caffeine exposure that includes intake from both coffee and non-coffee sources . In meta-analyses that included all but one of these 12 studies, the summary relative risk (RR) estimates for the highest versus lowest intakes suggested an 11% reduced risk among the case-control studies and a 10% reduced risk among the cohort studies . However, in both meta-analyses, the RR estimates were significantly heterogeneous, with individual studies suggesting positive , null and inverse associations with risk. Interestingly, 4 studies examining associations by menopausal status reported an increased ovarian cancer risk with caffeine intake among premenopausal women, whereas among postmenopausal women the associations were null or less strong .
Measurement of caffeine intake has been hindered in some studies, where questionnaires have not distinguished between decaffeinated vs. caffeinated coffee or tea , and only three studies included caffeine from green tea intake . Also, the time period for which caffeine intake has been assessed was often a single time point in late adulthood (i.e., in the last year before diagnosis or interview in the case-control studies or at baseline in the cohort studies). As the induction period for a potential effect of an exposure on ovarian cancer development likely occurs over decades, the measurement of exposure in most studies likely missed the etiologically relevant period.
The PRevention of OVArian Cancer in Quebec (PROVAQ) Study is a population-based case-control study that was conducted in Montreal, Canada. Using data from this study, we investigated lifetime caffeine intake in relation to epithelial ovarian cancer overall, and by menopausal status. Associations were also examined for invasive vs. borderline tumors, and for high-grade serous carcinomas (HGSC), the most common epithelial ovarian cancer type.