Table 3. Factors associated with phenotype change.

Variable	OR	95% CI	p-value
Univariate analysis
High histological grade (grade 3 vs. 1–2)	4.45	1.77–11.20	< 0.002
Ki-67 expression (continuous, 1% change)	1.07	1.03–1.10	< 0.001
Age (continuous)	1.01	0.98–1.05	0.464
Menopausal status (post vs. pre)	1.81	0.76–4.30	0.179
Tumor size (continuous)	1.05	0.92–1.21	0.437
Ductal histology (ductal vs. other)	1.06	0.35–3.18	0.922
Multivariate analysis
High histological grade	2.79	1.02–7.66	< 0.047
Ki-67 expression	1.05	1.00–1.09	< 0.037

OR=odds ratio; CI=confidence interval.