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Table 3 Associations between standardized percent mammographic breast density change and breast cancer risk, by age at BBD diagnosis and BBD histological classification

From: Temporal changes in mammographic breast density and breast cancer risk among women with benign breast disease

Standardized MBD change (%, per 2 years)

Age at BBD < 50 year (n = 173)

Age at BBD ≥ 50 year (n = 337)

P-interaction‡

Case n = 94

Control n = 79

p-value*

Multivariable Model

P-trend†

Standardized MBD change (%, per 2 years)

Case N = 167

Control N = 170

P-value*

Multivariable Model

p-trend†

N (%)

N (%)

OR (95 CI)†

N (%)

N (%)

OR (95 CI)†

Overall (N = 173)

Overall (N = 337)

  Stable/Increase ≥ 0%

13 (13.8)

13 (16.5)

0.77

0.79 (0.31, 2.01)

 

Increase ≥ 0%

52 (31.1)

52 (30.6)

0.21

1.17 (0.67, 2.05)

 

0.25

  Minimal decrease less than 5%

62 (66.0)

53 (67.1)

 

1.00 (Referent)

 

Decrease less than 5%

89 (53.3)

79 (46.5)

 

1.00 (Referent)

  

  Decrease more than 5%

19 (20.2)

13 (16.5)

 

1.10 (0.45, 2.70)

 

Decrease more than 5%

26 (15.6)

39 (22.9)

 

0.48 (0.25, 0.92)

  

  Trend

   

1.18 (0.68, 2.06)

0.56

Trend

   

0.66 (0.46, 0.96)

0.028

 

  Continuous

   

0.99 (0.92, 1.06)

0.73

Continuous

   

0.98 (0.94, 1.03)

0.46

 

Non-proliferative diagnosis (N = 127)

 

Non-proliferative diagnosis (N = 202)

  Stable/Increase ≥ 0%

9 (14.3)

11 (17.2)

0.82

0.87 (0.30, 2.56)

 

Increase ≥ 0%

31 (35.2)

32 (28.1)

0.44

1.43 (0.69, 2.93)

 

0.43

  Minimal decrease less than 5%

43 (68.3)

44 (68.8)

 

1.00 (Referent)

 

Decrease less than 5%

42 (47.7)

56 (49.1)

 

1.00 (Referent)

  

  Decrease more than 5%

11 (17.5)

9 (14.1)

 

1.07 (0.36, 3.21)

 

Decrease more than 5%

15 (17.1)

26 (22.8)

 

0.70 (0.30, 1.64)

  

  Trend

   

1.11 (0.58, 2.15)

0.75

Trend

   

0.70 (0.44, 1.12)

0.14

 

  Continuous

   

0.97 (0.88, 1.06)

0.48

Continuous

   

0.97 (0.92, 1.03)

0.35

 

Proliferative diagnosis (N = 46)

 

Proliferative diagnosis (N = 135)

  Stable/Increase ≥ 0%

4 (12.9)

2 (13.3)

–

–

 

Increase ≥ 0%

21 (26.6)

20 (35.7)

0.099

0.95 (0.36, 2.52)

 

0.64

  Minimal decrease less than 5%

19 (61.3)

9 (60.0)

 

–

 

Decrease less than 5%

47 (59.5)

23 (41.1)

 

1.00 (Referent)

  

  Decrease more than 5%

8 (25.8)

4 (26.7)

 

–

 

Decrease more than 5%

11 (13.9)

13 (23.2)

 

0.32 (0.11, 0.99)

  

  Trend

    

–

Trend

   

0.61 (0.32, 1.20)

0.15

 

  Continuous

    

–

Continuous

   

1.02 (0.95, 1.09)

0.67

 
  1. Standardized change in percent mammographic density (i.e., percent density change per two years) was calculated using percent density change from baseline to follow-up mammogram and divided by time intervals between two mammogram exams (percent density at follow-up mammogram − percent density at baseline mammogram)/(calendar years between baseline mammogram and follow-up mammogram/2). Missing values in breast cancer risk factors were imputed using multiple imputations. Result estimates were calculated in five imputed datasets, separately, and averaged using statistical procedures
  2. BBD benign breast disease, BMI body mass index, CI confidence interval, MBD mammographic breast density, OR odds ratio;
  3. *P values were calculated from Chi-Square tests; statistical significance is indicated using bold font. P value was not calculated for proliferative diagnosis among women age at BBD < 50 years due to small cell counts
  4. †Point estimates and 95% confidence interval were determined from multivariable unconditional logistic regression models adjusting for continuous age at BBD and follow-up time between BBD and breast cancer diagnosis, BBD calendar year, baseline percent density (quartiles), and BMI
  5. ‡p values for interactions of age at BBD (< 50 vs. ≥ 50 year) with percent density change (standard) after adjusting for matching factors, BMI, and baseline density (quartiles)
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Breast Cancer Research

ISSN: 1465-542X

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