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Table 3 Associations between physical activity and volumetric mammographic density among all women

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

Type of activity

N

%

Absolute dense volume (cm 3 )

Nondense volume (cm 3 )

Percent dense volume (%)

   

Unadjusted

Adjusted

Unadjusted

Adjusted

Unadjusted

Adjusted

β (95% CI)

β (95% CI) a

β (95% CI)

β (95% CI) a

β (95% CI)

β (95% CI) a

Total activity (MET-hours/day)

        

 < 40.0

12,180

31.3

Reference

Reference

Reference

Reference

Reference

Reference

 40.0 to 44.9

15,273

39.2

−2.7 (−3.5, −2.0)

−1.2 (−2.0, −0.4)

−86.9 (−97.8, −75.9)

−14.6 (−23.2, −6.0)

0.5 (0.4, 0.6)

0 (−0.1, 0.1)

 45.0 to 49.9

7,591

19.2

−3.1 (−4.0, −2.2)

−2.5 (−3.5, −1.5)

−138.4 (−151.3, −125.5)

−34.9 (−45.0, −24.9)

1.1 (0.9, 1.2)

0.1 (0, 0.2)

 ≥ 50.0

3,869

9.9

−2.4 (−3.5, −1.3)

−3.4 (−4.7, −2.3)

−110.7 (−127.6, −93.8)

−23.7 (−36.9, −10.4)

1.0 (0.8, 1.2)

0 (−0.2, 0.2)

P global b

  

<0.001

<0.001

<0.001

<0.001

<0.001

0.39

 For every 5 MET-hours/day increasec

  

−0.9 (−1.2, −0.6)

−1.1 (−1.3, −0.7)

−39.0 (−43.1, −35.0)

−8.5 (−12.0, −5.5)

0.3 (0.2, 0.4)

0 (−0.04, 0.04)

P trend d

  

<0.001

<0.001

<0.001

<0.001

<0.001

0.96

Moderate activity (hours/day)

        

 < 2.0

15,104

38.8

Reference

Reference

Reference

Reference

Reference

Reference

 2.0 to 4.9

12,300

31.6

−2.4 (−3.2, −1.7)

−0.3 (−1.1, 0.5)

−43.3 (−54.1, −32.5)

−4.8 (−13.3, 3.6)

0.1 (0, 0.2)

0 (−0.1, 0.1)

 5.0 to 6.9

5,729

14.7

−1.1 (−2.0, −0.1)

−1.0 (−2.1, 0)

−27.6 (−41.5, −13.8)

3.1 (−7.8, 14.0)

0.1 (0. 0.3)

−0.2 (−0.3, 0)

 ≥ 7.0

5,780

14.9

−1.0 (−1.9, 0)

−1.9 (−2.9, −0.9)

−63.1 (−77.0, −49.2)

−5.1 (−15.9, 5.7)

0.7 (0.5, 0.8)

−0.1 (−0.2, 0.1)

P global b

  

<0.001

<0.001

<0.001

0.41

<0.001

0.03

 For every 1 h/day increasec

  

−0.1 (−0.2, 0.02)

−0.3 (−0.4, −0.1)

−7.9 (−9.6, −6.2)

−0.5 (−1.8, 0.8)

0.1 (0.07, 0.1)

−0.02 (−0.03, 0)

P trend d

  

0.12

<0.001

<0.001

0.44

<0.001

0.09

Vigorous activity (hours/day)

        

 < 0.25

28,559

73.4

Reference

Reference

Reference

Reference

Reference

Reference

 0.25 to 0.49

6,237

16.0

−2.6 (−3.5, −1.7)

−2.6 (−3.5, −1.6)

−145.1 (−156.6, −133.6)

−43.1 (−52.1, −34.1)

1.2 (1.1, 1.4)

0.2 (0.1, 0.4)

 0.5 to 0.9

3,226

8.3

−4.9 (−6.0, −3.8)

−3.5 (−4.7, −2.3)

−163.2 (−178.1, −148.3)

−64.5 (−76.5, −52.5)

1.2 (1.0, 1.3)

0.4 (0.2, 0.6)

 ≥ 1.0

891

2.3

−5.3 (−7.4, −3.3)

−3.1 (−5.3, −1.0)

−134.9 (−164.0, −105.9)

−60.6 (−82.9, −38.4)

0.9 (0.6, 1.3)

0.6 (0.3, 0.9)

P global b

  

<0.001

<0.001

<0.001

<0.001

<0.001

<0.001

 For every 1 h/day increasec

  

−5.6 (−6.5, −4.6)

−3.9 (−4.9, −2.9)

−181.4 (−199.9, −162.8)

−62.7 (−75.6, −49.9)

1.3 (1.1, 1.5)

0.4 (0.2, 0.6)

P trend d

  

<0.001

<0.001

<0.001

<0.001

<0.001

<0.001

Recreational activity (hours/day)

        

 < 0.5

2,282

5.9

Reference

Reference

Reference

Reference

Reference

Reference

 0.5 to 0.9

5,170

13.3

−0.5 (−2.1, 1.0)

−0.7 (−2.3, 1.0)

−91.2 (−115.3, −67.0)

−40.4 (−59.7, −21.2)

0.7 (0.4, 0.9)

0.2 (0, 0.4)

 1.0 to 2.9

20,860

53.6

−2.5 (−3.9, −1.2)

−1.6 (−3.0, −0.1)

−138.0 (−159.5, −116.6)

−49.4 (−66.7, −32.2)

1.0 (0.8, 1.2)

0.3 (0.1, 0.5)

 ≥ 3.0

10,601

27.2

−4.3 (−5.7, −2.9)

−2.5 (−4.0, −1.0)

−160.7 (−183.0, −138.4)

−50.5 (−68.6, −32.5)

1.1 (0.9, 1.3)

0.3 (0.1, 0.5)

P global b

  

<0.001

<0.001

<0.001

<0.001

<0.001

0.02

 For every 1 hour/day increasec

  

−0.9 (−1.1, −0.7)

−0.5 (−0.7, −0.3)

−19.3 (−22.1, −16.6)

−4.4 (−6.7, −2.1)

0.1 (0.08, 0.1)

0.02 (0, 0.05)

P trend d

  

<0.001

<0.001

<0.001

<0.001

<0.001

0.09

  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 regression models using physical activity as a continuous exposure.