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Table 2 Adjusted odds ratios (OR) and 95% confidence intervals (CI) for association between breast cancer subtypes associated and reproductive factors

From: Parity, hormones and breast cancer subtypes - results from a large nested case-control study in a national screening program

 

Luminal A-like

Luminal B-like HER2-negative

Luminal B-like HER2-positive

HER2-positive

Triple-negative

ER+ PR+ HER2-

ER+ PR- HER2-

ER+ PR+/PR- HER2+

ER- PR- HER2+

ER- PR- HER2-

Controls (n)

Cases (n)

OR*

95% CI

Controls (n)

Cases (n)

OR

95% CI

Controls (n)

Cases (n)

OR

95% CI

Controls (n)

Cases (n)

OR

95% CI

Controls (n)

Cases (n)

OR

95% CI

Age at first birth (years)

 13–20

3951

746

1

Reference

1001

169

1

Reference

553

96

1

Reference

279

54

1

Reference

495

95

1

Reference

 21–22

2277

460

1.04

(0.91, 1.18)

620

120

1.22

(0.93, 1.59)

305

51

0.97

(0.65, 1.43)

170

32

0.97

(0.58, 1.62)

326

65

1.10

(0.77, 1.57)

 23–25

3152

591

0.97

(0.85, 1.10)

759

157

1.29

(1.00, 1.67)

437

92

1.27

(0.90, 1.78)

222

36

0.75

(0.46, 1.22)

393

86

1.27

(0.89, 1.81)

 26–30

2473

547

1.12

(0.98, 1.28)

647

141

1.30

(0.99, 1.71)

343

62

1.21

(0.82, 1.78)

216

41

0.97

(0.59, 1.58)

318

63

1.16

(0.79, 1.70)

 31–50

937

238

1.19

(0.99, 1.43)

223

60

1.60

(1.10, 2.32)

127

32

1.64

(0.98, 2.74)

63

23

1.67

(0.89, 3.12)

120

29

1.47

(0.88, 2.47)

 Never (nulliparous)

1199

328

1.76

(1.44, 2.15)

303

89

1.96

(1.31, 2.91)

164

49

2.74

(1.57, 4.78)

84

27

1.82

(0.85, 3.88)

144

34

1.58

(0.89, 2.81)

  p-trenda

  

0.07

   

0.01

   

0.06

   

0.49

   

0.16

 

  p-heterogeneity#

      

0.19

   

0.19

   

0.31

   

0.68

 

Number of pregnancies lasting 6+ months

 0

1199

328

1

Reference

303

89

1

Reference

164

49

1

Reference

84

27

1

Reference

144

34

1

Reference

 1

1596

397

0.91

(0.77, 1.08)

426

84

0.68

(0.48, 0.96)

229

42

0.53

(0.33, 0.86)

128

20

0.50

(0.26, 0.96)

224

41

0.70

(0.42, 1.16)

 2

6266

1302

0.76

(0.66, 0.88)

1602

323

0.68

(0.52, 0.90)

842

185

0.71

(0.49, 1.04)

426

97

0.78

(0.47, 1.29)

813

158

0.77

(0.50, 1.18)

 3

3883

721

0.66

(0.57, 0.77)

950

197

0.69

(0.52, 0.93)

528

89

0.54

(0.36, 0.82)

319

60

0.61

(0.36, 1.03)

477

117

0.98

(0.63, 1.53)

 >4

1518

237

0.56

(0.46, 0.68)

383

65

0.58

(0.40, 0.84)

225

31

0.42

(0.25, 0.70)

98

19

0.60

(0.31, 1.19)

196

36

0.70

(0.41, 1.21)

  p-trend

  

<0.0001

   

0.02

   

0.002

   

0.19

   

0.88

 

  p-heterogeneity

      

0.31

   

0.42

   

0.34

   

0.03

 

Parous women only

 Duration breastfeeding (months)

  No breastfeeding

997

204

1

Reference

260

51

1

Reference

146

33

1

Reference

78

10

1

Reference

135

24

1

Reference

  1–6

3145

607

0.95

(0.79, 1.15)

831

170

1.01

(0.70, 1.45)

449

74

0.66

(0.40, 1.07)

243

37

1.42

(0.63, 3.18)

467

80

1.01

(0.60, 1.71)

  7 − 12

3108

663

1.09

(0.91, 1.31)

763

158

1.05

(0.73, 1.51)

427

98

0.83

(0.51, 1.33)

215

52

2.25

(1.02, 4.99)

359

95

1.65

(0.98, 2.78)

  13 − 20

2583

496

1.02

(0.83, 1.24)

654

130

0.98

(0.67, 1.44)

343

77

0.90

(0.54, 1.49)

156

48

2.51

(1.11, 5.68)

308

69

1.29

(0.74, 2.23)

  21 − 30

1700

319

1.03

(0.83, 1.28)

399

79

0.97

(0.64, 1.46)

240

37

0.60

(0.33, 1.10)

147

28

1.78

(0.74, 4.28)

222

44

1.18

(0.65, 2.15)

  >30

966

195

1.15

(0.89, 1.48)

250

48

1.03

(0.63, 1.69)

121

16

0.69

(0.33, 1.47)

70

13

1.82

(0.67, 4.97)

123

24

1.19

(0.58, 2.44)

   p-trend

  

0.22

   

0.90

   

0.63

   

0.12

   

0.52

 

   p-heterogeneity

      

0.85

   

0.25

   

0.56

   

0.84

 

 Menopausal status

  Premenopausal

1171

351

1

Reference

208

47

1

Reference

173

32

1

Reference

100

18

1

Reference

130

29

1

Reference

  Perimenopausal

1055

229

0.61

(0.50, 0.74)

225

50

0.95

(0.60, 1.51)

152

26

0.86

(0.47, 1.54)

79

20

1.41

(0.67, 2.94)

143

37

1.13

(0.64, 1.99)

  Postmenopausal

12000

2405

0.51

(0.43, 0.60)

3231

661

0.84

(0.58, 1.23)

1663

338

1.11

(0.69, 1.78)

876

185

1.21

(0.66, 2.23)

1581

320

0.82

(0.50, 1.33)

   p-trend

  

<0.0001

   

0.30

   

0.46

   

0.71

   

0.21

 

   p-heterogeneity

      

<0.0001

   

0.01

   

0.001

   

0.003

 

 Age at menopause (years)

  <47

2558

450

1

Reference

638

136

1

Reference

333

47

1

Reference

203

22

1

Reference

336

61

1

Reference

  47–49

2393

449

1.09

(0.94, 1.26)

637

128

0.98

(0.74, 1.29)

321

60

1.48

(0.96, 2.27)

180

39

2.05

(1.14, 3.70)

291

72

1.50

(1.01, 2.24)

  50–52

4571

870

1.11

(0.98, 1.26)

1162

241

0.98

(0.77, 1.24)

644

131

1.59

(1.09, 2.32)

324

76

2.21

(1.31, 3.75)

611

102

1.04

(0.72, 1.49)

  >52

3051

633

1.12

(0.97, 1.28)

840

164

0.95

(0.73, 1.24)

415

94

1.70

(1.13, 2.55)

202

48

2.36

(1.33, 4.21)

395

88

1.38

(0.94, 2.01)

  Never (premenopausal)

1171

351

2.34

(1.93, 2.85)

208

47

1.17

(0.76, 1.80)

173

32

1.50

(0.86, 2.61)

100

18

1.76

(0.81, 3.80)

130

29

1.55

(0.88, 2.72)

   p-trenda

  

0.12

   

0.72

   

0.01

   

0.004

   

0.38

 

   p-heterogeneity

      

0.70

   

0.09

   

0.08

   

0.28

 
  1. aThe category Never was not included in the analysis of p-trend. *p for trend and OR mutually adjusted for age (50–54, 55–59, 60–64, 65–70 years at screening), body mass index (BMI) (≤22, 23–25, 26–28, >28 at screening), education (no education/primary school, high school, bachelor or master’s degree), age at menarche (9–12, 13, 14, 15–18 years), number of pregnancies (0, 1, 2, 3, ≥4), menopausal status (premenopausal, perimenopausal, postmenopausal). # p for heterogeneity across subtypes was determined in a case − case model (see “Methods”). ER estrogen receptor, PR progesterone receptor, HER2 human epidermal growth factor receptor 2
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Breast Cancer Research

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