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Table 4 Multivariable associations between physical activity and absolute dense volume (cm 3 ) stratified by 10-year breast cancer risk estimated by the Tyrer–Cuzick prediction model

From: Background risk of breast cancer and the association between physical activity and mammographic density

 

Breast cancer risk <3.0%

Breast cancer risk 3.0 to 4.9%

Breast cancer risk ≥5.0%

Type of activity

N

%

Multivariable-adjusted

N

%

Multivariable-adjusted

N

%

Multivariable-adjusted

β (95% CI) a

β (95% CI) a

  

β (95% CI) a

Total activity (MET-hours/day)

         

 < 40.0

5,791

29.5

Reference

4,499

32.6

Reference

1,890

34.4

Reference

 40 to 44.9

7,515

38.3

−1.9 (−3.1, −0.7)

5,567

40.4

−0.3 (−1.7, 1.0)

2,191

39.9

−0.7 (−2.7, 1.3)

 45.0 to 49.9

4,072

20.7

−3.3 (−4.7, −1.9)

2,520

18.3

−2.0 (−3.6, −0.4)

999

18.2

−0.5 (−3.2, 2.1)

 ≥ 50.0

2,255

11.5

−4.2 (−5.8, −2.6)

1,199

8.7

−2.2 (−4.4, 0)

415

7.6

−3.7 (−7.1, −0.3)

  P global b

  

<0.001

  

0.04

  

0.2

 For every 5 MET-hours/day increasec

  

−1.2 (−1.5, −0.8)

  

−0.7 (−1.2, −0.2)

  

−1.0 (−1.9, −0.3)

  P trend d

  

<0.001

  

0.01

  

0.01

  P interaction e

  

0.05

      

Moderate activity (hours/day)

         

 < 2.0

7,173

36.5

Reference

5,623

40.8

Reference

2,308

42.0

Reference

 2.0 to 4.9

6,100

31.1

0 (−1.2, 1.2)

4,431

32.1

−0.4 (−1.7, 0.9)

1,769

32.2

−0.7 (−2.7, 1.3)

 5.0 to 6.9

3,061

15.6

−1.1 (−2.6, 0.3)

1,920

13.9

−0.7 (−2.4, 1.0)

748

13.6

−0.7 (−3.5, 2.1)

 ≥ 7.0

3,299

16.8

−2.4 (−3.8, −1.0)

1,811

13.1

−1.1 (−2.9, 0.7)

670

12.2

−0.8 (−3.7, 2.0)

  P global

  

<0.001

  

0.65

  

0.88

 For every 1 hour/day increasec

  

−0.3 (−0.5, −0.1)

  

−0.1 (−0.4, 0.1)

  

−0.1 (−0.5, 0.2)

  P trend d

  

<0.001

  

0.14

  

0.40

  P interaction e

  

0.13

      

Vigorous activity (hours/day)

         

 < 0.25

14,190

72.3

Reference

10,262

74.4

Reference

4,107

74.7

Reference

 0.25 to 0.49

3,293

16.8

−2.8 (−4.1, −1.5)

2,118

15.4

−2.3 (−3.9, −0.7)

826

15.0

−2.2 (−4.7, 0.4)

 0.5 to 0.9

1,699

8.7

−3.3 (−5.0, −1.7)

1,084

7.9

−3.3 (−5.3, −1.2)

443

8.1

−4.4 (−7.2, −1.6)

 ≥ 1.0

451

2.3

−6.3 (−9.1, −3.5)

321

2.3

0.5 (−3.0, 4.1)

119

2.2

−0.2 (−5.9, 5.5)

  P global

  

<0.001

  

<0.001

  

0.01

 For every 1 hour/day increasec

  

−5.5 (−7.0, −4.1)

  

−1.7 (−3.3, −0.03)

  

−3.7 (−6.2, −1.1)

  P trend d

  

<0.001

  

0.05

  

0.01

  P interaction e

  

0.11

      

Recreational activity (hours/day)

         

 < 0.5

1,068

5.4

Reference

866

6.3

Reference

348

6.3

Reference

 0.5 to 0.9

2,450

12.5

0.8 (−1.7, 3.2)

1,906

13.8

−1.4 (−4.2, 1.3)

814

14.8

−3.0 (−7.0, 1.1)

 1.0 to 2.9

10,336

52.6

−1.3 (−3.4, 0.7)

7,514

54.5

−1.8 (−4.2, 0.6)

3,010

54.8

−1.6 (−5.2, 2.1)

 ≥ 3.0

5,779

29.4

−2.1 (−4.3, 0.1)

3,499

25.4

−2.4 (−5.0, 0.1)

1,323

24.1

−3.2 (−7.1, 0.7)

  P global

  

0.01

  

0.3

  

0.24

 For every 1 hour/day increasec

  

−0.5 (−0.8, −0.2)

  

−0.3 (−0.6, 0.1)

  

−0.6 (−1.2, −0.1)

  P trend d

  

<0.001

  

0.15

  

0.03

  P interaction e

  

0.37

      
  1. β, regression coefficient; CI, confidence interval; MET, metabolic equivalent of task. aAdjusted for age at mammography (5-year categories), body mass index (<25.0, 25.0 to 29.9, ≥30.0 kg/m2), family history of breast cancer in mother or sisters (yes, no), age at menarche (<13, 13, 14, ≥15 years), parity and age at first birth (nulliparous; one or two births, age at first birth <26 years; one or two births, age at first birth ≥26 years; ≥3 births, age at first birth <26 years; ≥3 births, age at first birth ≥26 years), oral contraceptives use (never, ever), menopausal status (premenopausal, postmenopausal), use of hormone replacement therapy (never, past, current), education level (secondary school, high school, university or higher, other), smoking status (never, past, current) and alcohol consumption (none, 0.1 to 9.9, 10.0 to 29.9, ≥30.0 g/day). b P global values were obtained from regression models using physical activity as a categorical exposure. cChange in volumetric mammographic density for every 5 MET-hours/day increase in total activity or every 1 hour/day increase in moderate, vigorous or recreational activity, respectively; from regression models using physical activity as a continuous exposure. d P trend values were obtained from regressions models using physical activity as a continuous exposure. e P interaction values were obtained from the nonstratified regression models by adding a product term between physical activity and the 10-year breast cancer risk as predicted using the Tyrer–Cuzick prediction model.
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Breast Cancer Research

ISSN: 1465-542X

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