Table 1

Breast cancer risk factors by menopausal status

Premenopausal womenPostmenopausal women
Cases n = 409Controls n = 493ORa (95% CI)Cases n = 868Control n = 1100ORa (95% CI)
Age in reference year (yrs)
 35–493504305591
 50–645963445549
 65–7900368460
Race/ethnicity
 Latina169234284442
 African American127130276321
 White113129308337
Country of birth
 United States-born3073171.06997651.0
 Foreign-born1021760.59 0.41–0.841693350.56 0.43–0.72
Education
 Some high school or less521291.02283711.0
 High school graduate73981.85 1.17–2.931852361.20 0.92–1.57
 Some college1471392.64 1.73–4.032732961.39 1.08–1.80
 College graduate1371272.82 1.82–4.381791961.37 1.02–1.84
Family history of breast cancer in first-degree relatives
 No3494471.0 7229611.0
 Yes57461.53 1.01–2.331451391.33 1.03–1.71
Prior biopsy for benign breast disease
 No3434601.0 6748821.0
 Yes65332.60 1.67–4.051892151.10 0.89–1.38
Age at menarche (yrs)
 8–11105991.0 2122271.0
 12–132052710.71 0.51–0.984355250.85 0.68–1.07
 ≥14981220.77 0.52–1.122083390.64 0.50–0.83
Age at menopauseb (yrs)
 <443144321.0
 45–544025331.03 0.84–1.25
 ≥55105871.61 1.15–2.23
Parity
 Nulliparous85661.17 0.75–1.841261071.37 0.95–1.97
 187741.0 1081281.0
 21251490.74 0.50–1.092122331.08 0.79–1.49
 363880.64 0.40–1.001652350.84 0.61–1.17
 422650.29 0.16–0.521201401.04 0.73–1.48
 ≥527510.47 0.29–0.771372570.66 0.47–0.92
Age at first full-term pregnancy (yrs)
 <20661181.0 2142841.0
 20–241111481.42 0.98–2.072973831.04 0.83–1.32
 25–2980791.91 1.26–2.911502040.98 0.74–1.30
 ≥3067811.74 1.12–2.69801100.98 0.70–1.38
 Nulliparous85662.33 1.52–3.591261071.52 1.10–2.08
Lifetime breastfeeding (months)
 Nulliparous85661.36 0.91–2.011261071.28 0.95–1.72
 01131201.0 3624051.0
 <121241431.02 0.73–1.432042660.87 0.69–1.09
 ≥12871640.63 0.44–0.901763220.63 0.50–0.80
Use of oral contraceptives
 Never53911.0 3865281.0
 Ever3153991.35 0.93–1.973795520.93 0.75–1.15
Use of HRT
 Never3504331.0
 Ever5076510.91 0.75–1.11
Caloric intake (tertiles)c
 Low1631771.0 2673581.0
 Medium1371770.86 0.63–1.172883591.12 0.90–1.41
 High1461790.93 0.68–1.282713601.13 0.90–1.43
BMI (tertiles)
 <26.11621641.0 
 26.1–31.91261620.76 0.55–1.06
 ≥32.01211640.70 0.50–0.97
BMI without history of HRT use
 <26.1891301.0
26.1–31.91201361.29 0.89–1.87
 ≥32.01391621.23 0.86–1.77
BMI with history of HRT use
 <26.12152301.0
 26.1–31.91542190.79 0.60–1.05
 ≥32.01371990.80 0.60–1.07
  • a Adjusted for age and race/ethnicity.

  • b Natural or surgical menopause.

  • c Premenopausal women, <1789 Kcal/day, 1789–2584 Kcal/day, ≥2585 Kcal/day; postmenopausal women, <1530 Kcal/day, 1530–2190 Kcal/day, ≥2191 Kcal/day.