Table 3

Case-only odds ratios and 95% confidence intervals from logistic regression modelsa of associations between breast cancer tumor subtypes and demographic, reproductive, and lifestyle risk factors, combined LACE and Pathways Studies (n = 2544)

Luminal A (comparison)

Luminal Ba


n

N

OR

95% CI


Age at diagnosis (years)

≥ 65 (Ref)

637

82

Ref

---

50 to 64

871

124

1.09

0.81, 1.47

< 50

355

88

1.83

1.32, 2.55

Test for trend

P = 0.0001

Race/ethnicity

White (Ref)

1464

215

Ref

---

African American

92

14

0.97

0.54, 1.74

Hispanic

135

28

1.32

0.85, 2.04

Asian

135

30

1.38

0.90, 2.12

Other

37

7

1.29

0.56, 2.94

Menopausal status

---

Postmenopausal (Ref)

1283

173

Ref

Premenopausal

406

95

1.32

0.87, 2.00

Family history

No (Ref)

1453

245

Ref

---

Yes

410

49

0.74

0.53, 1.02

Age at first full-term pregnancy (years)

Nulliparous (Ref)

335

51

Ref

---

< 26

959

158

1.25

0.88, 1.78

≥ 26

567

85

1.04

0.72, 1.52

Parity

Nulliparous (Ref)

335

51

Ref

---

1 to 2 children

837

150

1.24

0.88, 1.76

≥ 3 children

691

93

1.03

0.70, 1.50

Lifetime duration of breastfeeding

Never (Ref)

871

135

Ref

---

0 to 3 months

255

50

1.31

0.92, 1.88

≥ 4 months

711

100

0.86

0.65, 1.14

Parity among never breastfedb

Nulliparous (Ref)

321

50

Ref

---

1 to 2 children

326

59

1.38

(0.89, 2.13)

≥ 3 children

224

26

1.01

(0.58, 1.76)

Parity among 0 to 3 months breastfedb

1 to 2 children (Ref)

144

33

Ref

---

≥ 3 children

108

17

0.90

(0.45, 1.77)

Parity among ≥ 4 months breastfedb

1 to 2 children (Ref)

358

56

Ref

---

≥ 3 children

352

44

0.84

(0.54, 1.32)

Alcohol use

Never (Ref)

709

131

Ref

---

Ever

880

119

0.74

0.56, 0.98

Smoking history

Never (Ref)

921

163

Ref

---

≤ 10

251

39

0.86

0.59, 1.27

11 to 19

147

22

0.93

0.57, 1.51

≥ 20

531

68

0.80

0.59, 1.09

Hormone replacement therapy (postmenopausal only)

Never (Ref)

314

55

Ref

---

Ever

943

114

0.66

0.46, 0.94

Oral contraceptive use

Never (Ref)

647

110

Ref

---

Ever

1160

172

0.73

0.55, 0.96

BMI (kg/m2)c

< 25 (Ref)

785

134

Ref

---

25 to 29

563

79

0.92

0.67, 1.24

≥ 30

500

77

1.03

0.75, 1.41

BMI (kg/m2) among premenopausalb

< 25 (Ref)

223

50

Ref

---

25 to 29

99

21

1.11

0.62, 2.00

≥ 30

81

24

1.68

0.92, 3.07

BMI (kg/m2) among postmenopausalb

< 25 (Ref)

480

67

Ref

---

25 to 29

422

52

0.90

0.61, 1.33

≥ 30

372

50

0.99

0.66, 1.47


a Adjusted for age at diagnosis, race/ethnicity, and Pathways/LACE study origin except in models with age at diagnosis or race/ethnicity as main predictors.

b P for interaction not statistically significant (P > 0.05) in any tumor subtype model.

c BMI = body mass index one year pre-diagnosis (LACE) and around diagnosis (Pathways).

CI = confidence interval; OR = odds ratio.

Kwan et al. Breast Cancer Research 2009 11:R31   doi:10.1186/bcr2261

Open Data