Abstract B88: Plasma carotenoids, tocopherols, retinol and breast cancer risk: Results from the Shanghai Women's Health Study

Studies conducted in Western countries have suggested that lipophilic antioxidants, particularly carotenoids, may have preventive effects on the risk of breast cancer. We prospectively investigated the associations of serum levels of tocopherols, total retinol, total and specific types of carotenoids with the risk of developing breast cancer among Chinese women; a population with low risk of breast cancer and low prevalence of vitamin supplement use.

A nested case-control study was conducted within the cohort of the Shanghai Women’s Health Study including 365 newly-diagnosed cases and 726 individually-matched controls 40-70 years of age who provided a blood sample at baseline. Multivariate conditional logistic regression analyses were used to assess associations between breast cancer risk and antioxidants.

Overall, we did not observe significant associations between any of the tocopherols, retinol and most carotenoids, and breast cancer risk. Plasma levels of lycopene other than trans, 5-cis and 7-cis were associated with a reduced risk with an OR of 0.56 (95% CI: 0.32-0.97) for the highest quartile versus the lowest after adjusting for plasma levels of other antioxidants. This inverse association was seen predominantly among premenopausal women with a corresponding OR (95% CI) of 0.36 (0.16-0.80). We also found that trans α-cryptoxanthin was associated with a reduced risk of breast cancer in a dose-response manner, with a corresponding OR of 0.59 (95% CI: 0.34-1.01) (P trend, 0.02) and the inverse association for trans α-cryptoxanthin appeared in both pre- and post-menopausal women.

Our study did not show strong evidence for an overall protective effect of plasma lipophilic antioxidants on breast cancer risk. The few significant inverse associations for subtype carotenoids need to be confirmed in future studies.

Citation Information: Cancer Prev Res 2008;1(7 Suppl):B88.