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)

Characteristics	Ipsilateral Breast Events (IBE)	in situ IBEs	invasive IBEs	Invasive Breast Cancer Recurrence (IBCR)
	Among BCS (n = 359)	BCS	BCS	Among all (n = 458)
	HR (95 % CI)	HR (95 % CI)	HR (95 % CI)	HR (95 % CI)
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)

RT radiotherapy, BCS breast conserving surgery, IBE ipsilateral breast events, IBCR invasive breast cancer recurrence