Table 2 Patient- and tumor characteristics of the primary DCIS in relation to risk of a breast cancer event. Risk of an ipsilateral breast cancer event (IBE) including risk of in situ IBEs and invasive ipsilateral recurrence, respectively, and any invasive recurrence (IBCR) (univariate Cox regression analyses)

Age (years)

  < 50

Reference

Reference

Reference

Reference

 50–65

0.77 (0.44–1.31)

0.92 (0.41–2.05)

0.63 (0.30–1.32)

0.68 (0.41–1.12)

  > 65

1.19 (0.67–2.12)

1.31 (0.55–3.11)

1.09 (0.50–2.37)

0.98 (0.57–1.66)

Detection mode

 Screening

Reference

Reference

Reference

Reference

 Clinically

1.78 (1.04–3.07)

1.78 (0.81–3.91)

2.09 (0.98–4.42)

1.47 (0.93–2.35)

Type of Surgery

 BCS

-

-

-

Reference

 Mastectomy

-

-

-

0.55 (0.29–1.03)

RT after BCS

 No

Reference

Reference

Reference

Reference

 Yes

0.53 (0.33–0.86)

0.50 (0.25–1.01)

0.51 (0.27–0.98)

0.91 (0.59–1.41)

Tumor size (mm)

  ≤ 25

Reference

Reference

Reference

Reference

  > 25 / multifocal

1.14 (0.71–1.83)

1.88 (0.97–3.62)

0.64 (0.30–1.34)

0.89 (0.55–1.45)

Nuclear grade

 Grade 1

Reference

Reference

Reference

Reference

 Grade 2

0.90 (0.41–1.96)

1.05 (0.30–3.63)

0.73 (0.27–1.99)

0.82 (0.38–1.77)

 Grade 3

0.83 (0.39–1.79)

1.03 (0.30–3.49)

0.63 (0.23–1.69)

0.64 (0.30–1.37)

ER status

 Negative

Reference

Reference

Reference

Reference

 Positive

0.90 (0.52–1.55)

0.80 (0.38–1.71)

1.02 (0.47–2.22)

1.16 (0.70–1.93)

PR status

 Negative

Reference

Reference

Reference

Reference

 Positive

0.83 (0.52–1.32)

1.04 (0.53–2.02)

0.66 (0.35–1.27)

1.06 (0.69–1.63)