Table 4.

Logistic regression to predict NAC involvement by tumors^a

Parameter	Estimate	Standard error	Wald χ2	P > χ2
Intercept	−4.0670	0.6599	37.9797	<0.0001
Two-quadrant involvement	1.2319	0.5478	5.0574	0.0245
Three-quadrant involvement	1.1669	1.1390	1.0494	0.3056
Four-quadrant involvement	3.2843	0.6635	24.5053	<0.0001
Central location	2.2656	0.5148	19.3679	<0.0001
HER2 positive	0.7979	0.4398	3.2918	0.0696
Nuclear grade 2	0.1695	0.6163	0.0757	0.8732
Nuclear grade 3	0.0013	0.6208	1.1348	0.2867

^aIntercept = log(P/(1 − P)) for a reference patient. The reference patient is defined as the patient having zero on all of the variables. In our case, the reference patient is the patient with a tumor that has one quadrant involvement, no central location, negative for HER2 overexpression, and a nuclear grade of one. Thus, in our case, −4.0670 = log(P/(1 − P)) where P = 1.68%. It means for a reference patient, her chance of NAC involvement is 1.68%. P indicates the probability of the NAC involvement