January 21, 2013
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Higher carotenoid levels may reduce breast cancer risk

Women with higher circulating levels of carotenoids, including alpha-carotene and beta-carotene, were at a reduced risk for breast cancer, according to results of a pooled analysis.

Some prior studies of circulating carotenoids and breast cancer have resulted in an inverse association with at least one carotenoid. However, the specific carotenoid has varied from study to study, according to background information provided by researchers.

The current analysis of eight cohort studies included 3,055 patients and 3,956 matched controls. The study comprised more than 80% of all published prospective data on plasma or serum carotenoids and breast cancer, according to researchers.

The investigators recalibrated carotenoid levels of patients to a common standard by re-assaying 20 plasma or serum samples from each cohort together at the same laboratory. They did this to account for differences between laboratories and to examine population differences across studies.

The following carotenoids demonstrated statistically significant inverse associations with breast cancer:

  • Alpha-carotene (top vs. bottom quintile RR=0.87; 95% CI, 0.71-1.05).
  • Beta-carotene (RR=0.83; 95% CI, 0.7-0.98).
  • Lutein and zeaxanthin (RR=0.84; 95% CI, 0.7-1.01).
  • Lycopene (RR=0.78; 95% CI, 0.62-0.99).
  • Total carotenoids (RR=0.81; 95% CI, 0.68-0.96).

The researchers observed no statistically significant association between beta-cryptoxanthin and risk.

Tests for heterogeneity across studies were not statistically significant.

The investigators observed a stronger association for ER-negative tumors than ER-positive tumors for several carotenoids, including beta-carotene (ER-negative: top vs. bottom quintile RR=0.52; 95% CI, 0.36-0.77; ER-positive: RR=0.83; 95% CI, 0.66-1.04).