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Table 2 Relative risks calculated using random-effects meta-analysis and attributable risk fractions

From: Breast cancer risk prediction in women aged 35–50 years: impact of including sex hormone concentrations in the Gail model

Risk factor

RR estimates

Attributable risk (%) for Gail+ AMH + testosterone modelb

Gail

Gail + AMH

Gail + testosterone

Gail + AMH + testosterone

Age at menarche, years

    

0.67%

 < 12

1.00 (0.90, 1.11)

1.02 (0.91, 1.13)

1.00 (0.90, 1.11)

1.01 (0.91, 1.12)

 

 12–13

1.00 (0.90, 1.11)

1.01 (0.91, 1.12)

1.00 (0.90, 1.11)

1.01 (0.91, 1.12)

 

 ≥ 14

1.0 (ref)

1.0 (ref)

1.0 (ref)

1.0 (ref)

 

Age at first live birth, years

    

18.47%

 < 20

1.0 (ref)

1.0 (ref)

1.0 (ref)

1.0 (ref)

 

 20–24

1.11 (1.00, 1.24)

1.12 (1.00, 1.25)

1.12 (1.00, 1.26)

1.12 (1.00, 1.26)

 

 25–29 or nulliparous

1.24 (1.11, 1.38)

1.25 (1.12, 1.39)

1.26 (1.12, 1.41)

1.26 (1.13, 1.42)

 

 ≥ 30

1.38 (1.23, 1.54)

1.40 (1.25, 1.56)

1.41 (1.26, 1.58)

1.42 (1.27, 1.60)

 

Number of benign breast biopsies

   

8.13%

 0

1.0 (ref)

1.0 (ref)

1.0 (ref)

1.0 (ref)

 

 ≥ 1

1.58 (1.33, 1.88)

1.55 (1.31, 1.85)

1.59 (1.34, 1.89)

1.56 (1.31, 1.86)

 

Number of first-degree family members with breast cancera

6.56%

 0

1.0 (ref)

1.0 (ref)

1.0 (ref)

1.0 (ref)

 

 1

1.58 (1.32, 1.89)

1.57 (1.31, 1.88)

1.57 (1.30, 1.88)

1.56 (1.30, 1.87)

 

 > 1

2.49 (2.08, 2.99)

2.47 (2.06, 2.96)

2.45 (2.04, 2.94)

2.43 (2.03, 2.92)

 

AMH

    

19.38%

 Q1

1.0 (ref)

1.0 (ref)

 

 Q2

1.16 (1.04, 1.29)

1.15 (1.03, 1.28)

 

 Q3

1.34 (1.20, 1.49)

1.33 (1.19, 1.48)

 

 Q4

1.55 (1.39, 1.73)

1.53 (1.37, 1.70)

 

Testosterone

    

9.48%

 Q1

1.0 (ref)

1.0 (ref)

 

 Q2

1.08 (1.02, 1.15)

1.07 (1.00, 1.14)

 

 Q3

1.17 (1.10, 1.25)

1.14 (1.07, 1.22)

 

 Q4

1.27 (1.19, 1.35)

1.22 (1.15, 1.30)

 
  1. aThe number of first-degree family members with breast cancer was coded as either 0, 1, or > 1 affected relatives. For cohorts that collected family history as a no/yes variable, “yes” answers were assigned to the intermediate category (1 affected relative)
  2. bWe used the method described in Bruzzi et al. [49] to estimate attributable risk for a one-category increase (or decrease for age at menarche) in the risk factor. The Sister study was excluded from attributable risk estimation because all participants had a family history of breast cancer