BRCA1 and BRCA2 mutation carriers, oral contraceptive use, and breast cancer before age 50.
BACKGROUND
Understanding the effect of oral contraceptives on risk of breast cancer in BRCA1 or BRCA2 mutation carriers is important because oral contraceptive use is a common, modifiable practice.


METHODS
We studied 497 BRCA1 and 307 BRCA2 mutation carriers, of whom 195 and 128, respectively, had been diagnosed with breast cancer. Case-control analyses were conducted using unconditional logistic regression with adjustments for family history and familial relationships and were restricted to subjects with a reference age under 50 years.


RESULTS
For BRCA1 mutation carriers, there was no significant association between risk of breast cancer and use of oral contraceptives for at least 1 year [odds ratio (OR), 0.77; 95% confidence interval (95% CI), 0.53-1.12] or duration of oral contraceptive use (P(trend) = 0.62). For BRCA2 mutation carriers, there was no association with use of oral contraceptives for at least 1 year (OR, 1.62; 95% CI, 0.90-2.92); however, there was an association of elevated risk with oral contraceptive use for at least 5 years (OR, 2.06; 95% CI, 1.08-3.94) and with duration of use (OR(trend) per year of use, 1.08; P = 0.008). Similar results were obtained when we considered only use of oral contraceptives that first started in 1975 or later.


CONCLUSIONS
We found no evidence overall that use of oral contraceptives for at least 1 year is associated with breast cancer risk for BRCA1 and BRCA2 mutation carriers before age 50. For BRCA2 mutation carriers, use of oral contraceptives may be associated with an increased risk of breast cancer among women who use them for at least 5 years. Further studies reporting results separately for BRCA1 and BRCA2 mutation carriers are needed to resolve this important issue.
Haile
Robert W
RW
Department of Preventive Medicine, University of Southern California-Keck School of Medicine, 1441 Eastlake Avenue, MS 9175, Los Angeles, CA 90089-9175, USA. haile@usc.edu
Thomas
Duncan C
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McGuire
Valerie
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Felberg
Anna
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John
Esther M
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Milne
Roger L
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Hopper
John L
JL
Jenkins
Mark A
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Levine
A Joan
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Daly
Mary M
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Buys
Saundra S
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Senie
Ruby T
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Andrulis
Irene L
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Knight
Julia A
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Godwin
Andrew K
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Southey
Melissa
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McCredie
Margaret R E
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Giles
Graham G
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Andrews
Lesley
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Tucker
Katherine
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Miron
Alexander
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Apicella
Carmel
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Tesoriero
Andrea
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Bane
Anita
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Pike
Malcolm C
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Whittemore
Alice S
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D000328:Adult; D001315:Australia / Q000453:epidemiology; D001943:Breast Neoplasms / Q000453:epidemiology / Q000235:genetics*; D002170:Canada / Q000453:epidemiology; D002278:Carcinoma in Situ / Q000453:epidemiology / Q000235:genetics*; D018270:Carcinoma, Ductal, Breast / Q000453:epidemiology / Q000235:genetics*; D016022:Case-Control Studies; D003276:Contraceptives, Oral / Q000494:pharmacology*; D005260:Female; D019398:Genes, BRCA1 / Q000187:drug effects*; D024522:Genes, BRCA2 / Q000187:drug effects*; D020022:Genetic Predisposition to Disease; D006579:Heterozygote; D006801:Humans; D016015:Logistic Models; D008875:Middle Aged; D009154:Mutation / Q000187:drug effects*; D011960:Receptors, Estrogen / Q000187:drug effects; D011980:Receptors, Progesterone / Q000187:drug effects; D012307:Risk Factors; D011795:Surveys and Questionnaires; D013997:Time Factors; D014481:United States / Q000453:epidemiology
D003276:Contraceptives, Oral; D011960:Receptors, Estrogen; D011980:Receptors, Progesterone