Table 3 Univariate and multivariate Fine-Gray regression analyses of BCI in the NCR cohort

 Age^a

0.73 (0.50–1.06)

0.10

0.65 (0.42–0.99)

0.05

 Tumor size ( >20 mm vs ≤20 mm)

1.46 (0.95–2.26)

0.09

1.58 (0.95–2.65)

0.08

 Tumor grade (G2/G3 vs G1)

0.99 (0.59–1.66)

0.98

0.78 (0.45–1.35)

0.37

 Treatment (tamoxifen vs AI/sequential)

1.09 (0.69-1.71)

0.72

1.13 (0.72-1.81)

0.58

 BCI^b

3.63 (2.05–6.44)

<0.001

3.42 (1.87–6.26)

<0.001

 Age^a

1.33 (1.03–1.71)

0.03

1.30 (0.99–1.70)

0.05

 Tumor size (>20 mm vs ≤20 mm)

1.91 (1.26–2.90)

0.003

1.66 (1.06–2.58)

0.03

 Tumor grade (G2/G3 vs G1)

0.85 (0.31–2.33)

0.76

0.50 (0.17–1.42)

0.19

 Treatment (tamoxifen vs exemestane)

0.99 (0.66–1.48)

0.94

1.08 (0.71–1.65)

0.72

 BCI^b

7.81 (4.30–14.18)

<0.001

7.49 (3.97–14.11)

<0.001