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Oral contraceptives, postmenopausal hormones, and risk of asynchronous bilateral breast cancer: the WECARE Study Group
Journal article   Open access   Peer reviewed

Oral contraceptives, postmenopausal hormones, and risk of asynchronous bilateral breast cancer: the WECARE Study Group

Jane C Figueiredo, Leslie Bernstein, Marinela Capanu, Kathleen E Malone, Charles F Lynch, Hoda Anton-Culver, Marilyn Stovall, Lisbeth Bertelsen, Robert W Haile, Jonine L Bernstein, …
Journal of clinical oncology, Vol.26(9), pp.1411-1418
03/20/2008
DOI: 10.1200/jco.2007.14.3081
PMID: 18250348
url
https://doi.org/10.1200/jco.2007.14.3081View
Published (Version of record) Open Access

Abstract

To investigate whether oral contraceptive (OC) use and postmenopausal hormones (PMH) are associated with an increased risk of developing asynchronous bilateral breast cancer among women diagnosed with breast cancer younger than 55 years. The WECARE (Women's Environment, Cancer, and Radiation Epidemiology) study is a population-based, multicenter, case-control study of 708 women with asynchronous bilateral breast cancer and 1,395 women with unilateral breast cancer. Risk factor information collected during a telephone interview focused on exposures before and after the first breast cancer diagnosis. Treatment and tumor characteristics were abstracted from medical records. Multivariable conditional logistic regression was used to estimate rate ratios (RR) and 95% CIs. OC use before the first breast cancer diagnosis was not associated with risk of asynchronous bilateral breast cancer (RR = 0.88; 95% CI, 0.67 to 1.16). OC use after breast cancer diagnosis was also not significantly associated with risk (RR = 1.56; 95% CI, 0.71 to 3.45). Risk did not increase with longer duration of use or among women who had begun using OCs at a younger age. No evidence of an increased risk of asynchronous bilateral breast cancer was observed with PMH use before (RR = 1.21; 95% CI, 0.90 to 1.61) or after breast cancer diagnosis (RR = 1.10; 95% CI, 0.67 to 1.77). Neither duration nor type of PMH were associated with risk. Age at and time since first breast cancer diagnosis did not substantially affect these results. This study provides no strong evidence that OC or PMH use increases the risk of a second cancer in the contralateral breast.
 Multivariate Analysis United States - epidemiology Neoplasms, Second Primary - ethnology Humans Middle Aged Gonadal Steroid Hormones - blood Case-Control Studies Breast Neoplasms - therapy Neoplasms, Second Primary - chemically induced Contraceptives, Oral - administration & dosage Postmenopause Adult Female Registries Surveys and Questionnaires Contraceptives, Oral - adverse effects Odds Ratio Breast Neoplasms - ethnology Breast Neoplasms - epidemiology Contraceptives, Oral, Hormonal - adverse effects Risk Assessment Risk Factors Logistic Models Neoplasms, Second Primary - epidemiology Denmark - epidemiology Aged Breast Neoplasms - chemically induced

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