Do flavonoids or black tea lower risk of ovarian cancer?

Studies of the impact of diet on risk of ovarian cancer are limited and their results unclear but a new report based on data from the Nurses’ Health Study (NHS) suggests a possible association between high intake of flavonoids and black tea and lower risk of the disease. The authors caution, however, that additional prospective studies are needed to confirm their findings.

Writing in the American Journal of Clinical Nutrition, researchers from the University of East Anglia and Harvard University described their prospective study of associations between flavonoids and risk of ovarian cancer in the NHS and NHS II cohort of more than 170,000 women. Their findings are based on multivariate-adjusted analyses of medical records data from 16 to 22 years’ follow-up, during which 723 cases of ovarian cancer were reported in the study group.

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Total flavonoid intake was not statistically significantly associated with ovarian cancer risk (HR for the top compared with the bottom quintile: 0.85; 95% CI: 0.66, 1.09; P-trend = 0.17). A modestly lower-but not statistically significant-risk of ovarian cancer was seen, however, in women with the highest quintiles of flavonol and flavanone intake versus the lowest quintile (HRs 0.76 [95% CI: 0.58, 0.98; P-trend = 0.11] and 0.79 [95% CI: 0.63, 1.00; P-trend = 0.26).

The association for flavonone intake was stronger for serous invasive and poorly differentiated tumors (comparable HR: 0.68; 95% CI: 0.50, 0.92; P-heterogeneity = 0.10, P-trend = 0.07) compared with nonserous and less-aggressive tumors. Intake of other subclasses of flavonoids was not significantly associated with risk. A food-based comparison of women who consumed >1 and ≤1 cup of black tea per day showed an HR of 0.68 (95% CI: 0.51, 0.90; P<0.01), suggesting that intake of the drink may be associated with a lower risk of ovarian cancer.

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