Table 4.

A. Risk of invasive breast cancer among BRCA mutation carriers who first used oral contraceptives in 1975 or later according to oral contraceptive use, by BRCA mutation status
BRCA1 mutation carriers
BRCA2 mutation carriers
Cases* (n = 140), n (%)Controls* (n = 242), n (%)OR (95% CI)Cases* (n = 87), n (%)Controls* (n = 123), n (%)OR (95% CI)
Oral contraceptive use for ≥1 y
    No49 (35)86 (36)1.0019 (22)45 (37)1.00
    Yes91 (65)156 (64)0.76 (0.48-1.20)68 (78)78 (63)2.11 (1.05-4.23)
Duration of use (y)
    <149 (35)86 (36)1.0019 (22)45 (37)1.00
    1-430 (22)63 (26)0.71 (0.41-1.25)11 (13)25 (20)1.02 (0.44-2.40)
    ≥560 (43)91 (38)0.78 (0.49-1.26)57 (66)53 (43)2.72 (1.26-5.85)
    Trend per year0.98 (P = 0.50)1.06 (P = 0.004)
B. Risk of invasive breast cancer according to oral contraceptive use for women less than 40 years of age, by BRCA mutation carrier status, among BRCA mutation carriers who first used oral contraceptives in 1975 or later

BRCA1 mutation carriers
BRCA2 mutation carriers
Cases* (n = 100), n (%)
Controls* (n = 179), n (%)
OR (95% CI)
Cases* (n = 64), n (%)
Controls* (n = 91), n (%)
OR (95% CI)
Oral contraceptive use for ≥1 y
    No26 (26)49 (27)1.0010 (16)26 (29)1.00
    Yes74 (74)130 (73)0.65 (0.36-1.19)54 (84)65 (71)1.21 (0.56-2.58)
Duration of use (y)
    <126 (26)49 (28)1.0010 (16)26 (29)1.00
    1-424 (24)55 (31)0.63 (0.32-1.24)7 (11)20 (22)0.43 (0.13-1.42)
    ≥549 (50)74 (42)0.62 (0.33-1.17)47 (73)45 (49)1.56 (0.68-3.58)
    Trend per year0.97 (P = 0.24)1.09 (P = 0.08)
  • * The totals for the different variables may not equal to the total number of subjects in a category because of missing data.

  • Adjusted for age, study site, family history, and number of full-term pregnancies.