Cancer Causes & Control

, Volume 16, Issue 9, pp 1059–1063

Oral Contraceptive Use and Risk of Breast Cancer among Women with a Family History of Breast Cancer: a Prospective Cohort Study

  • Stephanie A. N. Silvera
  • Anthony B. Miller
  • Thomas E. Rohan
Article

DOI: 10.1007/s10552-005-0343-1

Cite this article as:
Silvera, S.A.N., Miller, A.B. & Rohan, T.E. Cancer Causes Control (2005) 16: 1059. doi:10.1007/s10552-005-0343-1

Abstract

Family history of breast cancer is an established risk factor for breast cancer. In addition, there is evidence that oral contraceptive use may be associated with a moderate increase in breast cancer risk. The three cohort studies that have investigated the relationship between oral contraceptive use and breast cancer risk among women with a family history of breast cancer have yielded mixed results, possibly due to the relatively small sample sizes employed and/or differences in the selection of covariates for inclusion in multivariate models. Therefore, we examined the association between oral contraceptive use and breast cancer risk in a large cohort study in Canada. The cohort consisted of the 27,318 women in the Canadian National Breast Screening Study who reported a family history of breast cancer on enrolment into the study. Linkages to national mortality and cancer databases yielded data on deaths and cancer incidence, with follow-up ending between 1998 and 2000, depending upon the province. During a mean of 16.0 years of follow-up, we observed 1707 incident cases of breast cancer among women with any history of breast cancer of which 795 cases occurred among women with a mother, sister, and/or daughter with breast cancer. Among women with any family history of breast cancer, ever use of oral contraceptives was associated with a 12% reduction in risk of breast cancer (95% confidence interval [CI]=0.73–1.07), and there was an inverse trend with increasing duration of use of borderline statistical significance (ptrend=0.03). Although we also observed a 25% lower risk of breast cancer associated with oral contraceptive use of greater than 84 months versus never use among women with a first degree relative with breast cancer, this finding was not statistically significant (95% CI=0.47–1.19, ptrend=0.48). Our data raise the possibility that relatively long duration of oral contraceptive use may be inversely associated with risk among women with a family history of breast cancer.

Keywords

breast neoplasm oral contraceptives family history prospective cohort National Breast Screening Study 

Copyright information

© Springer 2005

Authors and Affiliations

  • Stephanie A. N. Silvera
    • 1
  • Anthony B. Miller
    • 2
  • Thomas E. Rohan
    • 1
  1. 1.Department of Epidemiology and Population HealthAlbert Einstein College of MedicineNYUSA
  2. 2.Department of Public Health SciencesUniversity of TorontoTorontoCanada
  3. 3.Department of Epidemiology and Population HealthAlbert Einstein College of MedicineNYUSA

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