OA Epidemiology

The Association between Use of Oral Contraceptive and Risk of Breast Cancer in BRCA1/2 Mutation Carriers

Proceedings of the 2013 annual meeting of the Netherlands Epidemiology Society

Volume 1 Issue S1 Abstract 56

 

L.H. Schrijver, Netherlands Cancer Institute, Amsterdam, The Netherlands
D.F. Easton, University of Cambridge, Cambridge, United Kingdom
N. Andrieu, Institute Curie, Paris, France
D.E. Goldgar, University of Utah, Salt Lake City, USA
K. Kast, University of Dresden, Dresden, Germany
A. Pijpe, Netherlands Cancer Institute, Amsterdam, The Netherlands
A.C. Antoniou, University of Cambridge, Cambridge, United Kingdom
M.A. Rookus, Netherlands Cancer Institute, Amsterdam, The Netherlands

Background
Women with BRCA1/2 mutations are at increased risk of breast cancer. An important ongoing area of research is whether factors that alter breast cancer risk in the general population also affect risks in carriers. Previous studies on the association between breast cancer risk and oral contraceptive (OC) use in BRCA1/2 carriers were inconclusive. A weak point of previous studies is the retrospective design. Our study is the first prospective study among BRCA1/2 carriers investigating the association between OC and breast cancer risk.

Methods
In the International BRCA1/2 Carrier Cohort study (IBCCS), a prospective cohort of 1,686 BRCA1 carriers was analyzed with a time-dependent Cox regression model. We restricted our analyses to women (n=1286) with complete OC exposure data. Follow-up was restricted to a maximum of 2 year after the last questionnaire.

Results
Our data suggested an increased risk of breast cancer for women who used OC (Current: HR 2.27 95%CI 0.86-5.99;  Past: HR 1.85 95%CI 0.88-2.86).  The increased risk slowly reduced after stopping, but still seemed present 10 years after OC use (Current: HR 2.41 95%CI 0.90-6.43; 1-4yrs ago: HR 1.85 95%CI 0.82-4.14;  5-9yrs ago: HR 1.91 95%CI 0.91-4.03;  ≥10yrs ago: HR 1.48 95%CI 0.81-2.73).

Conclusion
These first prospective analyses support findings in the general population showing a temporal increased risk of breast cancer during OC use in BRCA1 carriers. The increased risk seemed somewhat higher and to last longer after stopping OC use than in the general population, but power was too low to draw any definitive conclusions.

Published: 06 Jun, 2013

 
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