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Table 2 Associations between OC or HRT use and breast cancer defined by ESR1 A908G mutation status

From: Risk factors for breast cancer characterized by the estrogen receptor alpha A908G (K303R) mutation

Risk factor

Controls (n= 790)

Mutation-positive cases (n= 37)

Mutation-positive cases vs. controls

Mutation-negative cases (n= 616)

Mutation-negative cases vs. controls

Mutation-positive vs. mutation-negative cases

 

n

(%)

n

(%)

ORa

95% CI

n

(%)

ORa

95% CI

ORa

95% CI

OC use

   Never

319

(40.4)

14

(37.8)

1.00

---

224

(36.5)

1.00

---

1.00

---

   Ever

470

(59.6)

23

(62.2)

1.72

0.66–4.44

390

(63.5)

1.15

0.87–1.52

1.53

0.61–3.84

OC duration

   Never

319

(40.4)

14

(37.8)

1.00

---

224

(36.5)

1.00

---

1.00

---

   <5 years

232

(29.4)

8

(21.6)

1.08

0.35–3.38

194

(31.6)

1.27

0.94–1.73

1.01

0.33–3.06

   5–10 years

162

(20.5)

8

(21.6)

1.75

0.53–5.77

123

(20.0)

0.95

0.67–1.35

1.79

0.59–5.43

   >10 years

76

(9.6)

7

(8.9)

3.73

1.16–12.03

73

(11.9)

1.18

0.77–1.81

2.66

0.81–8.67

   Ptrend

     

0.02

   

0.84

 

0.07

Age at first use of OCs

   Never

319

(40.4)

14

(37.8)

1.00

---

224

(36.6)

1.00

---

1.00

---

   ≤20 years

215

(27.2)

8

(21.6)

1.18

0.32–4.42

192

(31.4)

0.99

0.69–1.41

1.44

0.41–5.09

   >20 years

255

(32.3)

15

(40.5)

1.81

0.71–4.63

196

(32.0)

1.20

0.89–1.60

1.56

0.61–3.96

Age at last use of OCs

   Never

319

(40.4)

14

(37.8)

1.00

---

224

(36.6)

1.00

---

1.00

---

   ≤30 years

273

(34.6)

10

(27.0)

1.18

0.36–3.90

226

(36.9)

1.10

0.80–1.52

1.39

0.45–4.25

   >30 years

197

(25.0)

13

(35.1)

1.97

0.75–5.15

162

(26.5)

1.16

0.85–1.58

1.63

0.62–4.29

Year of first OC use

   Never

319

(40.4)

14

(37.8)

1.00

---

224

(36.6)

1.00

---

1.00

---

   ≤1975

389

(49.3)

19

(51.4)

1.72

0.67–4.43

292

(47.7)

1.15

0.87–1.52

1.54

0.61–3.89

   >1975

81

(10.3)

4

(10.8)

1.51

0.28–8.12

96

(15.7)

0.98

0.62–1.55

1.58

0.35–7.13

First use before first full-term pregnancy

   No

233

(54.8)

11

(57.9)

1.00

---

169

(51.1)

1.00

---

1.00

---

   Yes

192

(45.2)

8

(42.1)

0.66

0.15–2.93

162

(48.9)

1.12

0.76–1.66

0.78

0.18–3.31

Recency of OC use (years since stopping)

   Never

319

(42.3)

14

(37.8)

1.00

---

224

(39.4)

1.00

---

1.00

---

   10+

374

(49.5)

17

(45.9)

1.70

0.65–4.43

278

(48.8)

1.15

0.86–1.52

1.52

0.59–3.92

   <10

62

(8.2)

6

(16.2)

3.63

0.80–16.45

67

(11.8)

1.06

0.65–1.72

3.65

0.86–15.47

   Ptrend

     

0.10

   

0.56

 

0.10

OC duration and recency of use (years since stopping)

   Never

319

(42.3)

14

(37.8)

1.00

---

224

(39.4)

1.00

---

1.00

---

   <10, <10

31

(4.1)

2

(5.4)

1.43

0.19–10.77

32

(5.6)

0.84

0.44–1.58

3.04

0.46–20.06

   <10, 10+

315

(41.7)

13

(35.1)

1.53

0.55–4.26

245

(43.1)

1.21

0.90–1.62

1.25

0.46–3.41

   10+, <10

31

(4.1

4

(10.8)

6.49

1.32–31.89

35

(6.2)

1.32

0.73–2.38

3.53

0.73–17.09

   10+, 10+

59

(7.8)

4

(10.8)

1.93

0.52–7.11

33

(5.8)

0.81

0.49–1.35

3.01

0.78–11.59

Postmenopausal HRT use

   Never

219

(50.3)

13

(59.1)

1.00

---

180

(61.0)

1.00

---

1.00

---

   Ever

216

(49.7)

9

(40.9)

0.83

0.28–2.42

115

(39.0)

0.62

0.44–0.87

1.23

0.42–3.61

Postmenopausal HRT duration

   Never

219

(50.3)

13

(59.1)

1.00

---

180

(61.0)

1.00

---

1.00

---

   <5 years

105

(24.1)

3

(13.6)

0.60

0.14–2.51

56

(19.0)

0.61

0.40–0.92

1.37

0.30–6.24

   5+ years

111

(25.6)

6

(27.3)

1.07

0.31–3.70

59

(20.0)

0.64

0.42–0.96

1.17

0.35–3.91

  1. aORs adjusted for sampling fraction, age, race, menopausal status (where appropriate), first-degree family history of breast cancer, parity/age first full-term pregnancy, breast feeding (ever, never), smoking status (never, former, current), alcohol intake (ever, never), age at menarche (<11, 11–12, 13, 14+), and body mass index (<25, 25 to <30, 30+). CI, confidence interval; ESR1, estrogen receptor alpha; HRT, hormone replacement therapy; OC, oral contraceptive; OR, odds ratio.