Table 2.

Treatment received in the sample before and after matching

	Table 2 Before matching					Table 2 After matching
	No SLNB N = 13,106		SLNB N = 2409		χ 2	No SLNB N = 4718		SLNB N = 2409		χ 2
	N	%	N	%	p value	N	%	N	%	p value
Preoperative MRI					< 0.001					< 0.001
Yes	1072	8.2	495	20.5		542	11.5	495	20.5
No	12,034	91.8	1914	79.5		4176	88.5	1914	79.5
Mastectomy					< 0.001					< 0.001
Yes	593	4.5	413	17.1		237	5.0	413	17.1
No	12,513	95.5	1996	82.9		4481	95.0	1996	82.9
Radiotherapy					0.001					0.48
Yes	7237	55.2	1416	58.8		2814	59.6	1416	58.8
No	5869	44.8	993	41.2		1904	40.4	993	41.2

SLNB sentinel lymph node biopsy, MRI magnetic resonance imaging