Journal Article

Caregiving Stress, Endogenous Sex Steroid Hormone Levels, and Breast Cancer Incidence

Candyce H. Kroenke, Susan E. Hankinson, Eva S. Schernhammer, Graham A. Colditz, Ichiro Kawachi and Michelle D. Holmes

in American Journal of Epidemiology

Published on behalf of Johns Hopkins Bloomberg School of Public Health

Volume 159, issue 11, pages 1019-1027
Published in print June 2004 | ISSN: 0002-9262
Published online June 2004 | e-ISSN: 1476-6256 | DOI:
Caregiving Stress, Endogenous Sex Steroid Hormone Levels, and Breast Cancer Incidence

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Stress is hypothesized to be a risk factor for breast cancer. The authors examined associations of hours of, and self-reported levels of stress from, informal caregiving with prospective breast cancer incidence. Cross-sectional analyses of caregiving and endogenous sex steroid hormones were also conducted. In 1992 or 1996, 69,886 US women from the Nurses’ Health Study, aged 46–71 years at baseline, answered questions on informal caregiving; 1,700 incident breast cancer cases accrued over follow-up to 2000. A subset of 665 postmenopausal women not taking exogenous hormones returned a blood sample in 1990. Numbers of hours of care provided to an ill adult or to a child were each summed and analyzed as 0 (reference), 1–14, and ≥15 per week. Cox proportional hazards models were used in prospective analyses and linear models in cross-sectional analyses. High numbers of caregiving hours and self-reported stress did not predict a higher incidence of breast cancer. However, compared with women providing no adult care, women providing ≥15 hours of adult care (median, 54) had significantly lower levels of estradiol (geometric mean, 9.21 pg/ml vs. 7.46 pg/ml (95% confidence interval: 6.36, 8.76)) and bioavailable estradiol (geometric mean, 1.86 pg/ml vs. 1.35 pg/ml (95% confidence interval: 1.00, 1.82)). Stress from caregiving did not appear to increase breast cancer risk.

Keywords: breast neoplasms; caregivers; cohort studies; gonadal steroid hormones; stress, psychological

Journal Article.  6746 words. 

Subjects: Public Health and Epidemiology

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