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J Natl Cancer Inst. 1999 Jun 16;91(12):1067-72.

Urinary 2-hydroxyestrone/16alpha-hydroxyestrone ratio and risk of breast cancer in postmenopausal women.

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1
Department of Preventive Medicine, University of Southern California/Norris Comprehensive Cancer Center, Los Angeles 90033, USA.

Abstract

BACKGROUND:

It has been suggested that women who metabolize a larger proportion of their endogenous estrogen via the 16alpha-hydroxylation pathway may be at elevated risk of breast cancer compared with women who metabolize proportionally more estrogen via the 2-hydroxylation pathway. However, the supporting epidemiologic data are scant. Consequently, we compared the ratio of urinary 2-hydroxyestrone (2-OHE1) to 16alphahydroxyestrone (16alpha-OHE1) in postmenopausal women with breast cancer and in healthy control subjects.

METHODS:

Estrogen metabolites were measured in urine samples obtained from white women who had participated in a previous population-based, breast cancer case-control study at our institution. All P values are from two-sided tests.

RESULTS:

All of the urinary estrogens measured, with the exception of estriol, were higher in the 66 case patients than in the 76 control subjects. The mean value of urinary 2-OHE1 in case patients was 13.8% (P = .20) higher than that in control subjects, 16alpha-OHE1 was 12.1% (P = .23) higher, estrone was 20.9% higher (P = .14), and 17beta-estradiol was 12.0% higher (P = .36). The ratio of 2-OHE1 to 16alpha-OHE1 was 1.1% higher in the patients (P = .84), contrary to the hypothesis. Compared with women in the lowest third of the values for the ratio of urinary 2-OHE1 to 16alpha-OHE1, women in the highest third were at a nonstatistically significantly increased risk of breast cancer (odds ratio = 1.13; 95% confidence interval = 0.46-2.78), again contrary to the hypothesis.

CONCLUSION:

This study does not support the hypothesis that the ratio of the two hydroxylated metabolites (2-OHE1/16alpha-OHE1) is an important risk factor for breast cancer.

PMID:
10379970
[Indexed for MEDLINE]
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