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Meta-Analysis
. 2002 Apr 17;94(8):606-16.
doi: 10.1093/jnci/94.8.606.

Endogenous sex hormones and breast cancer in postmenopausal women: reanalysis of nine prospective studies

T Key  1 , P Appleby, I Barnes, G Reeves, Endogenous Hormones and Breast Cancer Collaborative Group
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Meta-Analysis

Endogenous sex hormones and breast cancer in postmenopausal women: reanalysis of nine prospective studies

T Key et al. J Natl Cancer Inst. .
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Abstract

Background: Reproductive and hormonal factors are involved in the etiology of breast cancer, but there are only a few prospective studies on endogenous sex hormone levels and breast cancer risk. We reanalyzed the worldwide data from prospective studies to examine the relationship between the levels of endogenous sex hormones and breast cancer risk in postmenopausal women.

Methods: We analyzed the individual data from nine prospective studies on 663 women who developed breast cancer and 1765 women who did not. None of the women was taking exogenous sex hormones when their blood was collected to determine hormone levels. The relative risks (RRs) for breast cancer associated with increasing hormone concentrations were estimated by conditional logistic regression on case-control sets matched within each study. Linear trends and heterogeneity of RRs were assessed by two-sided tests or chi-square tests, as appropriate.

Results: The risk for breast cancer increased statistically significantly with increasing concentrations of all sex hormones examined: total estradiol, free estradiol, non-sex hormone-binding globulin (SHBG)-bound estradiol (which comprises free and albumin-bound estradiol), estrone, estrone sulfate, androstenedione, dehydroepiandrosterone, dehydroepiandrosterone sulfate, and testosterone. The RRs for women with increasing quintiles of estradiol concentrations, relative to the lowest quintile, were 1.42 (95% confidence interval [CI] = 1.04 to 1.95), 1.21 (95% CI = 0.89 to 1.66), 1.80 (95% CI = 1.33 to 2.43), and 2.00 (95% CI = 1.47 to 2.71; P(trend)<.001 the rrs for women with increasing quintiles of free estradiol were ci="0.94" to and p magnitudes risk associated other estrogens androgens similar. shbg was a decrease in breast cancer increases increased levels all sex hormones remained after subjects who diagnosed within years blood collection excluded from analysis.>

Conclusion: Levels of endogenous sex hormones are strongly associated with breast cancer risk in postmenopausal women.

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