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Table 1 Combined relative risks for breast cancer associated with different classifications of mammographic density, study designs, and study populations from meta-analysis [3]

From: Mammographic density, breast cancer risk and risk prediction

 

General population

Symptomatic population

 

Incidence studies

Prevalence studies

  

Classification

Cases/Non-casesa

RR (95% CI)

Cases/Non-casesa

RR (95% CI)

Cases/Non-casesa

RR (95% CI)

Wolfe parenchymal pattern

2,664/23,469b

  

2,169/32,184b

 

1,857/25,394b

 

   N1

181/3,613

1.0

557/15,731

1.0

428/3,318

1.0

   P1

525/6,682

1.8 (1.4, 2.2)

519/9,684

1.3 (1.0, 1.5)

315/5,031

1.0 (0.77, 1.3)

   P2

1,162/10,433

3.1 (2.5, 3.7)

660/4,369

2.0 (1.3, 3.0)

526/5,128

1.5 (0.91, 2.4)

   DY

246/2,309

4.0 (2.5, 6.3)

294/2,216

2.4 (2.0, 3.0)

400/4,976

1.7 (1.0, 2.8)

Percentage mammographic density

4,508/8,342b

  

2,219/4,063b

 

160/160b

 

   <5%

1,194/1,744c

1.0

643/1,182c

1.0

35/84c

1.0

   5%–24%

 

1.8 (1.5, 2.2)

 

1.4 (1.1, 1.8)

  

   25%–49%

1,049/1,045

2.1 (1.7, 2.6)

589/835

2.2 (1.8, 2.8)

66/35

5.5 (2.8–11)

   50%–74%

 

2.9 (2.5, 3.4)

438/665

2.9 (2.3, 3.8)

34/23

4.8 (2.2–11)

   75%+

1,211/999

4.6 (3.6, 5.9)

190/282

3.7 (2.7, 5.0)

25/18

4.3 (1.8–10)

BI-RADS

1,992/104,663b

Vacekand Geller [30]

Ziv et al. [57]

397/1,589b

   

   Fatty

62/7,550

1.0 (Ref)

0.3 (0.2, 0.4)

20/134

1.0

  

   Scattered density

950/52,379

2.2 (1.6, 3.0)

1.0 (Ref)

216/957

1.6 (0.9, 2.8)

  

   Heterogeneous density

783/36,564

3.0 (2.2, 4.1)

1.3 (1.1, 1.5)

117/407

2.3 (1.3, 4.3)

  

   Extremely dense

197/8,170

4.0 (2.8, 5.7)

20.1 (1.6, 2.8)

44/91

4.5 (1.9, 10.6)

  
  1. aCases and controls from individual categories may not add to the overall number of cases and controls used in the meta-analysis since categories from individual studies did not always coincide with those presented in the meta-analysis. Only numbers of cases and controls from studies with these categories are presented and used for the calculation of prevalence. bTotal cases and noncases used in meta-analysis by McCormack and colleagues [3] for each classification and study type. cWhen possible, categories were combined to provide the maximum contribution of cases and controls from individual studies. BI-RADS, Breast Imaging Reporting and Data System; CI, confidence interval; Ref, reference; RR, relative risk.