Table 3.

Rate of positive margins on first excision and total volume excised to achieve negative margins: a comparison of Perpendicular and Cavity Shave methods, by T stage and presence of EIC.

	Smaller extent of disease				Larger extent of disease
	Perpendicular	Cavity-Shave	p-value		Perpendicular	Cavity-Shave	p-value
Rate of positive margins on first excision
T1 (≤2cm)	13%	12%	0.69	T2/3 (>2cm)	27%	14%	0.20
No EIC	14%	11%	0.50	EIC	19%	15%	0.67
T1 and no EIC	13%	11%	0.56	T2/T3 or EIC	23%	15%	0.34
Median total volume excised to achieve negative margins (ml)
T1 (≤2cm)	47ml	61ml	0.03	T2/3 (>2cm)	95ml	69ml	0.47
No EIC	48ml	63ml	0.02	EIC	86ml	55ml	0.34
T1 and no EIC	45ml	63ml	0.01	T2/T3 or EIC	86ml	61ml	0.14

T stage, American Joint Commission on Cancer tumor stage; EIC, extensive intraductal component

Note: p-values derived from linear regression models using natural logarithm of total volume to negative margins.