Table 5.

Multivariable binary logistic regression model of variables associated with overall mastectomy

		p value	Odds ratio	95% CI
MRI referral	noMRI	Reference	–	–
	Screening MRI	< 0.001	2.4	1.5–3.8
	Diagnostic MRI	0.957	1.0	0.8–1.3
	Preoperative MRI	< 0.001	1.9	1.6–2.2
Breast density	ACR BI-RADS class a	Reference	–	–
	ACR BI-RADS class b	0.081	1.2	1.0–1.5
	ACR BI-RADS class c	0.017	1.3	1.1–1.7
	ACR BI-RADS class d	< 0.001	1.8	1.3–2.5
Breast cancer risk	Familial breast cancer risk	0.003	2.2	1.3–3.7
Hormonal status	Postmenopausal	Reference	–	–
	Premenopausal	< 0.001	1.6	1.4–1.9
	Perimenopausal	0.434	1.1	0.9–1.4
Lesion focus at DM	No observable lesion	Reference	–	–
	Single focus	0.005	0.7	0.6–0.9
	Multifocal	0.578	1.1	0.8–1.5
	Multicentric	0.002	2.5	1.4–4.5
Largest lesion diameter at DM	≥ 20 mm	< 0.001	1.8	1.5–2.1
Lesion focus at US	No observable lesion	Reference	–	–
	Single focus	0.194	0.9	0.7–1.1
	Multifocal	< 0.001	1.8	1.3–2.4
	Multicentric	< 0.001	4.2	2.1–8.2
Largest lesion diameter at US	≥ 20 mm	< 0.001	1.8	1.5–2.2
Core-needle or vacuum-assisted biopsy	Pure DCIS	< 0.001	1.7	1.3–2.2
	Lobular component	< 0.001	1.5	1.2–1.9
Surgical pathology	Pure DCIS	< 0.001	0.6	0.4–0.8
	DCIS associated to invasive cancer	0.005	0.8	0.7–0.9
	Largest lesion size ≥ 20 mm	< 0.001	1.8	1.5–2.1
	Multifocal or multicentric cancer	< 0.001	3.9	3.2–4.7

CI, confidence interval; ACR BI-RADS, American College of Radiology Breast Imaging Data and Reporting System; DM, digital mammography; US, ultrasonography; MRI, magnetic resonance imaging; DCIS, ductal carcinoma in situ