Table 4. Multivariate survival analysis using Cox proportional hazards regression models.

Model	Variable	Category	Hazard ratio	95% CI	p value
1	pT stage	T1 vs. T2-4	3.397	1.403–8.223	0.007
	pN stage	N0 vs. N1-3	4.024	1.610–10.057	0.003
	Lymphovascular invasion	Absent vs. present	1.097	0.462–2.608	0.834
	Estrogen receptor	≥90% vs. <90%	1.735	0.811–3.710	0.156
	Progesterone receptor	≥40% vs. <40%	1.900	0.886–4.075	0.099
	Ki-67 index by average method	<18% vs. ≥18%	2.431	1.088–5.434	0.030
2	T stage	T1 vs. T2-4	3.212	1.319–7.823	0.010
	N stage	N0 vs. N1-3	4.038	1.614–10.100	0.003
	Lymphovascular invasion	Absent vs. present	1.056	0.445–2.505	0.902
	Estrogen receptor	≥90% vs. <90%	1.634	0.764–3.494	0.205
	Progesterone receptor	≥40% vs. <40%	1.971	0.919–4.226	0.081
	Ki-67 index by hot spot method	<22% vs. ≥22%	3.058	1.287–7.267	0.011

P values were calculated from Cox proportional hazards regression models with backward stepwise selection.

Abbreviation: CI, confidence interval