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Table 1 Demographics of study participants at time of recruitment to the Predicting Risk of Cancer At Screening (PROCAS) study*

From: A comparison of five methods of measuring mammographic density: a case-control study

 

Study 1

 

Study 2

 

PROCAS

Control subjects

Case subjects

 

Control subjects

Case subjects

 

(n = 57902)

(n = 1098)

(n = 366)

 

(n = 1014)

(n = 338)

 

Number

Percent

Number

Percent

P value

Number

Percent

Number

Percent

P value

Number

Percent

Age at consent (years)

 < 50

117

10.7

40

10.9

 

50

4.9

17

5.0

 

7173

12.4

 50–54

316

28.8

104

28.4

 

203

20.0

66

19.5

 

16962

29.3

 55–59

157

14.3

53

14.5

 

179

17.7

61

18.0

 

11046

19.1

 60–64

237

21.6

79

21.6

 

315

31.1

105

31.1

 

11223

19.4

 65–69

197

17.9

66

18.0

 

210

20.7

70

20.7

 

8552

14.8

 70+

74

6.7

24

6.6

1.000

57

5.6

19

5.6

1.000

2946

5.1

 Median (IQR)

58

51–64

58

51–64

0.988

61

55–65

61

55–65

0.965

57

51–63

Menopausal status

 Perimenopausal

170

15.5

57

15.6

 

145

14.3

49

14.5

 

10760

18.6

 Postmenopausal

747

68.0

248

67.8

 

769

75.8

256

75.7

 

37201

64.2

 Premenopausal

136

12.4

46

12.6

 

67

6.6

22

6.5

 

6869

11.9

 Unknown

45

4.1

15

4.1

1.000

33

3.3

11

3.3

1.000

3072

5.3

HRT use

 Never

699

63.7

250

68.3

 

518

51.1

177

52.4

 

36505

63.0

 Previous

342

31.1

93

25.4

 

379

37.4

122

36.1

 

16438

28.4

 Current

56

5.1

19

5.2

 

110

10.8

37

10.9

 

4421

7.6

 Unknown

1

0.1

4

1.1

0.302a

7

0.7

2

0.6

0.972

538

0.9

BMI (kg/m2)

 < 25

345

31.4

112

30.6

 

334

32.9

108

32.0

 

20774

35.8

 25–29

353

32.1

122

33.3

 

346

34.1

118

34.9

 

18969

32.8

 ≥ 30

327

29.8

105

28.7

 

272

26.8

88

26.0

 

14256

24.6

 Unknown

73

6.6

27

7.4

0.918

62

6.1

24

7.1

0.904

3933

6.8

 Median (IQR)

27.2

24.0–31.2

27.8

24.0–30.8

0.581

26.6

23.9–30.5

26.6

23.9–30.5

0.517

26.4

23.6–30.3

Ethnic origin

 White

1038

94.5

334

91.3

 

924

91.1

304

89.9

 

52689

91.0

 Other/unknown

50

4.6

32

8.7

0.003

90

8.9

34

10.1

0.511

5213

9.0

Year of mammogram

            

 2009

22

2.0

0

0.0

      

2372

4.1

 2010

607

55.3

43

11.7

 

196

19.3

70

20.7

 

14761

25.5

 2011

396

36.1

130

35.5

 

553

54.5

177

52.4

 

18350

31.7

 2012

70

6.4

129

35.2

 

264

26.0

86

25.4

 

14214

24.5

 2013

3

0.3

30

8.2

 

1

0.1

3

0.9

 

3499

6.0

 2014

0

0.0

33

9.0

 

0

0.0

2

0.6

 

3804

6.6

 2015

0

0.0

1

0.3

< 0.001b

    

0.769c

900

1.6

Initial Tyrer-Cuzick (10-year %)

 Median (IQR)

2.72

2.18 – 3.52

2.95

2.29–3.90

0.003

2.63

2.10–3.47

2.91

2.25–4.02

< 0.001

2.67

2.12–3.47

Family history

 None

803

73.1

249

68.0

 

754

74.4

229

67.8

 

42367

73.2

 FDR only

104

9.5

42

11.5

 

107

10.6

47

13.0

 

5749

9.9

 SDR only

147

13.4

51

13.9

 

126

12.4

42

12.4

 

7998

13.8

 FDR and SDR

44

4.0

24

6.6

0.112

27

2.7

20

5.9

0.008

1788

3.1

Current alcohol use

 No

283

25.8

89

24.3

 

273

26.9

93

27.5

 

15815

27.3

 Yes

797

72.6

269

73.5

 

726

71.6

241

71.3

 

41130

71.0

 Unknown

18

1.6

8

2.2

0.697

15

1.5

4

1.2

0.908

957

1.7

Any children

 No

128

11.7

43

11.7

 

98

9.7

45

13.3

 

7384

12.7

 Yes

970

88.3

323

88.3

 

915

90.2

290

85.8

 

50411

87.1

 Unknown

    

0.963

1

0.1

3

0.9

0.023d

107

0.2

Prior biopsy of breast

 No

910

82.9

284

77.6

 

837

82.5

252

74.6

 

47359

81.8

 Yes

159

14.5

65

17.8

 

153

15.1

76

22.5

 

8911

15.4

 Unknown

29

2.6

17

4.6

0.041

24

2.4

10

3.0

0.005

1632

2.8

  1. *In study 1 cases are women with breast cancer detected at first screen on entry to the PROCAS study and in study 2 cases are women with breast cancer detected within PROCAS at a subsequent screen or between screening rounds
  2. IQR interquartile range, HRT hormone replacement therapy, BMI body mass index, FDR first-degree relative, SDR second-degree relative
  3. aExcludes unknown
  4. b2013-2015 combined
  5. c2012-2014 combined
  6. dUnknown combined with no children