American Journal of Epidemiology Advance Access originally published online on February 6, 2007
American Journal of Epidemiology 2007 165(9):1007-1014; doi:10.1093/aje/kwk105
| ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
ORIGINAL CONTRIBUTIONS |
Preeclampsia, Pregnancy-related Hypertension, and Breast Cancer Risk
1 Department of Epidemiology, Mailman School of Public Health, Columbia University, New York, NY
2 Department of Community Medicine, Mt. Sinai School of Medicine, New York, NY
3 Department of Epidemiology, School of Public Health, University of North Carolina, Chapel Hill, NC
Correspondence to Dr. Mary Beth Terry, Department of Epidemiology, Mailman School of Public Health, Columbia University, New York, NY 10032 (e-mail: mt146{at}columbia.edu).
Received for publication July 17, 2006. Accepted for publication October 13, 2006.
Pregnancy conditions accompanied by high blood pressure, such as preeclampsia and pregnancy-related hypertension, have been associated with a lower risk of breast cancer in several epidemiologic studies. It is unknown whether length of gestation or multiple occurrence of these conditions alters the association with breast cancer. It is also unknown whether the inverse association between preeclampsia and breast cancer risk is modified by menopausal status at breast cancer diagnosis. Using data from a large, population-based case-control study of breast cancer conducted on Long Island, New York, during 1996–1997, the authors examined these questions among ever-parous women (1,310 cases and 1,385 controls) using multivariate logistic models. Preeclampsia was inversely associated with breast cancer (odds ratio = 0.7, 95% confidence interval: 0.5, 1.0); this association was even stronger among women who had multiple occurrences of preeclampsia (odds ratio = 0.3, 95% confidence interval: 0.1, 0.9). The risk reduction was more pronounced among postmenopausal women. Gestation length did not substantially alter the relation between preeclampsia and breast cancer risk. Pregnancy-related hypertension was also inversely associated with breast cancer risk, but the relations were not statistically significant after adjustment for preeclampsia. These data suggest that pregnancy conditions related to hypertension, particularly preeclampsia, play a role in reducing breast cancer risk. Possible biologic mechanisms underpinning these associations should be further explored.
breast neoplasms; hypertension, pregnancy-induced; pre-eclampsia; pregnancy
Abbreviations: CI, confidence interval; OR, odds ratio