title: A prospective study of urinary oestrogen excretion and breast cancer risk.
abstract: To test the hypothesis that high levels of endogenous oestrogens increase the risk for developing breast cancer, concentrations of oestrone, oestradiol and oestriol were measured in 24 h urine samples from 1000 women participants in a prospective study of breast cancer on the island of Guernsey. Sixty-nine subjects were diagnosed with breast cancer subsequent to urine collection. Among women who were premenopausal at the time of urine collection, cases excreted less oestrogen than controls; the odds ratios (95% CI) for breast cancer in the middle and upper thirds of the distribution of oestrogen excretion, in comparison with the lower third (reference group, assigned odds ratio = 1.0), were 0.5(0.2-1.2) and 0.4(0.2-1.1) respectively for oestrone, 0.8(0.4-1.8 and 0.4(0.2-1.1) for oestradiol, 0.7(0.3-1.6) and 0.7(0.3-1.6) for oestriol and 0.9(0.4-2.0) and 0.5(0.2-1.3) for total oestrogens. Among women who were post-menopausal at the time of urine collection, the trend was in the opposite direction, with an increase in risk associated with increased oestrogen excretion; the odds ratios were 0.9(0.3-2.2) and 1.1(0.5-2.8) for oestrone, 0.8(0.3-2.3) and 1.9(0.8-4.6) for oestradiol, 1.5(0.6-3.9) and 1.8(0.7-4.6) for oestriol and 0.9(0.4-2.6) and 1.9(0.7-4.7) for total oestrogens. The trends of increasing risk with increasing oestrogen excretion among post-menopausal women were statistically significant for oestradiol (P = 0.022) and for total oestrogens (P = 0.016). We conclude that high levels of endogenous oestrogens in post-menopausal women are associated with increased breast cancer risk, but that the relationship of oestrogens in premenopausal women with risk is unclear.
authors.affiliation: Imperial Cancer Research Fund, Cancer Epidemiology Unit, Radcliffe Infirmary, Oxford, UK.
authors.forename: T J
authors.initials: TJ
authors.lastname: Key
authors.forename: D Y
authors.initials: DY
authors.lastname: Wang
authors.forename: J B
authors.initials: JB
authors.lastname: Brown
authors.forename: C
authors.initials: C
authors.lastname: Hermon
authors.forename: D S
authors.initials: DS
authors.lastname: Allen
authors.forename: J W
authors.initials: JW
authors.lastname: Moore
authors.forename: R D
authors.initials: RD
authors.lastname: Bulbrook
authors.forename: I S
authors.initials: IS
authors.lastname: Fentiman
authors.forename: M C
authors.initials: MC
authors.lastname: Pike
mesh_terms: D000328:Adult; D001943:Breast Neoplasms / Q000453:epidemiology / Q000209:etiology* / Q000652:urine*; D016022:Case-Control Studies; D004958:Estradiol / Q000652:urine; D004964:Estriol / Q000652:urine; D004967:Estrogens / Q000652:urine*; D004970:Estrone / Q000652:urine; D005260:Female; D006801:Humans; D008875:Middle Aged; D017698:Postmenopause / Q000652:urine; D017697:Premenopause / Q000652:urine; D011446:Prospective Studies; D012307:Risk Factors
chemical_list: D004967:Estrogens; D004970:Estrone; D004958:Estradiol; D004964:Estriol