Dataset Information

Breast Cancer and Menopausal Hormone Therapy by Race/Ethnicity and Body Mass Index.

ABSTRACT: In analyses combining estrogen with or without progestin, some observational studies describe minimal breast cancer risk in obese and black women. Therefore, we examined these suggested interactions in the two Women's Health Initiative (WHI) randomized hormone therapy trials. The estrogen plus progestin trial entered 16 608 postmenopausal women with a uterus, while the estrogen trial entered 10 736 postmenopausal women with prior hysterectomy. Hazard ratios (HRs), 95% confidence intervals (CIs), and P values from log-rank x(2) statistics were estimated from Cox proportional hazards models with subgroup analyses based on tests of interaction. All statistical tests were two-sided. Estrogen plus progestin statistically significantly increased breast cancer incidence (HR = 1.28, 95% CI = 1.11 to 1.48, P < .001), with hazard ratios greater than 1 in all body mass index (BMI) subgroups (P interaction = .58) and hazard ratios greater than 1 in black and white women (P interaction = .96). In contrast, estrogen alone statistically significantly decreased breast cancer incidence (HR = 0.79, 95% CI = 0.65 to 0.90, P = .02), with hazard ratios lower than 1 in all BMI subgroups (P interaction = .86) and hazard ratios lower than 1 in black and white women, where analyses with limited numbers suggest somewhat greater reduction in black women (P interaction = .09). In summary, estrogen plus progestin and estrogen alone have opposite effects on breast cancer incidence, with no statistically significant interactions by race/ethnicity or BMI. Therefore, observational studies should not combine these two regimens when examining breast cancer risk.

SUBMITTER: Chlebowski RT

PROVIDER: S-EPMC5943827 | biostudies-other | 2016 Feb

REPOSITORIES: biostudies-other

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Breast Cancer and Menopausal Hormone Therapy by Race/Ethnicity and Body Mass Index.

Chlebowski Rowan T RT Anderson Garnet L GL Aragaki Aaron K AK Prentice Ross R

Journal of the National Cancer Institute 20151105 2

In analyses combining estrogen with or without progestin, some observational studies describe minimal breast cancer risk in obese and black women. Therefore, we examined these suggested interactions in the two Women's Health Initiative (WHI) randomized hormone therapy trials. The estrogen plus progestin trial entered 16 608 postmenopausal women with a uterus, while the estrogen trial entered 10 736 postmenopausal women with prior hysterectomy. Hazard ratios (HRs), 95% confidence intervals (CIs), ...[more]

PMID: 26546117

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Project description:BackgroundThyroxine (T4) has been positively associated with tumor cell proliferation, while the effect of triiodothyronine (T3) on cell proliferation has not been well-established because it differs according to the type of cell line used. In Mexico, it has been reported that 14.5% of adult women have some type of thyroid dysfunction and abnormalities in thyroid function tests have been observed in a variety of non-thyroidal illnesses, including breast cancer (BC). These abnormalities might change with body mass index (BMI) because thyroid hormones are involved in the regulation of various metabolic pathways and probably by menopausal status because obesity has been negatively associated with BC in premenopausal women and has been positively associated with BC in postmenopausal women.MethodsTo assess the association between serum thyroid hormone concentration (T4 and T3) and BC and the influence of obesity as an effect modifier of this relationship in premenopausal and postmenopausal women, we measured serum thyroid hormone and thyroid antibody levels in 682 patients with incident breast cancer (cases) and 731 controls, who participated in a population-based case-control study performed from 2004 to 2007 in three states of Mexico. We tested the association of total T4 (TT4) and total T3 (TT3) stratifying by menopausal status and body mass index (BMI), and adjusted for other health and demographic risk factors using logistic regressions models.ResultsHigher serum total T4 (TT4) concentrations were associated with BC in both premenopausal (odds ratio (OR) per standard deviation?=?5.98, 95% CI 3.01-11.90) and postmenopausal women (OR per standard deviation?=?2.81, 95% CI 2.17-3.65). In premenopausal women, the effect of TT4 decreased as BMI increased while the opposite was observed in postmenopausal women. The significance of the effect modification was marginal (p?=?0.059) in postmenopausal women and was not significant in premenopausal women (p?=?0.22). Lower TT3 concentrations were associated with BC in both premenopausal and postmenopausal women and no effect modification was observed.ConclusionsThere is a strong association between BC and serum concentrations of TT3 and TT4; this needs to be further investigated to understand why it happens and how important it is to consider these alterations in treatment.

Dataset Information

Breast Cancer and Menopausal Hormone Therapy by Race/Ethnicity and Body Mass Index.

Publications

Breast Cancer and Menopausal Hormone Therapy by Race/Ethnicity and Body Mass Index.

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