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Cancer Epidemiology, Biomarkers & Prevention : a Publication of the American Association for Cancer Research, Cosponsored by the American Society of Preventive Oncology, 17(11), 3170-3178, 2008

Effect of reproductive factors and oral contraceptives on breast cancer risk in BRCA1/2 mutation carriers and noncarriers: results from a population-based study

Roberta McKean‐Cowdin , Leslie Bernstein , Eunjung Lee

Author affiliations (5)
  • University of Southern California ROR
  • Centers for Disease Control and Prevention ROR
  • The Centers ROR
  • Division of Cancer Etiology, Department of Population Sciences, City of Hope Medical Center, Duarte, California; Departments of 2Preventive Medicine and 3Pathology, Keck School of Medicine, Univers... ROR
  • Department of Preventive Medicine, Keck School of Medicine, University of Southern California/Norris Comprehensive Cancer Center, Los Angeles, California;
DOI10.1158/1055-9965.EPI-08-0396 PMID18990759
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Abstract

Background

Multiparity and breast-feeding reduce breast cancer risk, whereas oral contraceptive use may slightly increase breast cancer risk in the general population. However, the effects of these factors in BRCA1 and BRCA2 mutation carriers are less clear.

Methods

Case patients were 1,469 women from Los Angeles County ages 20 to 49 years with newly diagnosed breast cancer. Control subjects were 444 women without breast cancer, individually matched to a subset of cases on race, age, and neighborhood. BRCA1/2 genes were sequenced in the cases, and odds ratios of breast cancer associated with various reproductive and hormonal factors in BRCA1/2 mutation carriers and noncarriers were estimated using multivariable logistic regression.

Results

Ninety-four women had a deleterious BRCA1 or BRCA2 mutation. Number of full-term pregnancies was inversely associated with breast cancer risk regardless of BRCA1/2 mutation status. Longer breast-feeding duration was protective among noncarriers but not among mutation carriers; however, this apparent effect modification was not statistically significant (P = 0.23). Neither oral contraceptive use overall nor the use of low-dose oral contraceptives was associated with an increased risk of breast cancer in any subgroup.

Conclusions

Our results suggest that parity protects against breast cancer in BRCA1/2 mutation carriers, whereas breast-feeding does not. Our data suggest no association between oral contraceptive use and breast cancer risk in BRCA1/2 mutation carriers. Further confirmation that currently available low-dose oral contraceptives do not increase breast cancer risk in carriers is important from a public health perspective given the high prevalence of oral contraceptive use in the United States.

Topics

Contraception/Comparison > Oral Contraceptives > Breast Cancer RiskGeneral OB/GYN > Breast Health > BRCA Mutation CarriersContraception/Comparison > Health Outcomes > Cancer Risk
BRCA1 BRCA2 mutation carriers oral contraceptive breast cancer risk, parity breastfeeding breast cancer risk BRCA mutation, reproductive factors breast cancer risk gene mutation carriers, oral contraceptive use breast cancer population-based case control, low-dose oral contraceptives BRCA breast cancer risk, multiparity protective effect breast cancer BRCA carriers, full-term pregnancies inverse association breast cancer, breastfeeding duration breast cancer noncarriers versus carriers, Los Angeles County breast cancer young women BRCA sequencing, hormonal contraception breast cancer hereditary risk
PMID 18990759 18990759 DOI 10.1158/1055-9965.EPI-08-0396 10.1158/1055-9965.EPI-08-0396

Cite this article

Lee, E., Ma, H., McKean-Cowdin, R., Van Den Berg, D., Bernstein, L., Henderson, B. E., & Ursin, G. (2008). Effect of reproductive factors and oral contraceptives on breast cancer risk in BRCA1/2 mutation carriers and noncarriers: results from a population-based study. *Cancer epidemiology, biomarkers & prevention : a publication of the American Association for Cancer Research, cosponsored by the American Society of Preventive Oncology*, *17*(11), 3170-3178. https://doi.org/10.1158/1055-9965.EPI-08-0396

Keywords

Contraceptives, Oral, Hormonal

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