Table 2.

Univariate and multivariate analyses for 15-year distant metastasis-free survival

	Sagara Hospital + AMC
	Univariate			Multivariate
	Hazard ratio	95% CI	P value	Hazard ratio	95% CI	P value
BCT risk (low vs. high)	7.20	3.80–13.65	< 0.001	4.59	2.13–9.88	< 0.001
Tumor size (≤ 2 cm vs. > 2 cm)	4.33	2.28–8.22	< 0.001	1.72	0.81–3.67	0.161
Positive nodes (0–3)	1.79	1.19–2.70	0.005	1.05	0.63–1.77	0.839
Histologic grade (1 vs. 2/3)	3.12	1.11–8.80	0.031	2.18	0.76–6.26	0.146
Age (≤ 50 vs. > 50 years)	2.05	1.03–4.06	0.041	1.38	0.67–2.86	0.383

	Sagara Hospital (Japan)
	Univariate			Multivariate
	Hazard ratio	95% CI	P value	Hazard ratio	95% CI	P value
BCT risk (low vs. high)	7.18	2.88–17.89	< 0.001	3.92	1.38–11.14	0.010
Tumor size (≤ 2 cm vs. > 2 cm)	3.73	1.50–9.31	0.005	1.62	0.59–4.50	0.353
Positive nodes (0–3)	2.55	1.61–4.04	< 0.001	2.06	1.18–3.58	0.011
Histologic grade (1 vs. 2/3)	6.82	1.58–29.51	0.010	6.26	1.43–27.45	0.015
Age (≤ 50 vs. > 50 years)	0.83	0.33–2.07	0.687	–	–	–

	AMC (Korea)
	Univariate			Multivariate
	Hazard ratio	95% CI	P value	Hazard ratio	95% CI	P value
BCT risk (low vs. high)	7.26	2.94–17.90	< 0.001	4.22	1.46–12.19	0.008
Tumor size (≤ 2 cm vs. > 2 cm)	4.95	2.01–12.20	< 0.001	1.64	0.56–4.83	0.371
Positive nodes (0–3)	0.95	0.33–2.75	0.929	–	–	–
Histologic grade (1 vs. 2/3)	1.70	0.39–7.37	0.477	–	–	–
Age (≤ 50 vs. > 50 years)	4.58	1.52–13.81	0.007	2.60	0.79–8.56	0.115

AMC, Asan Medical Center; CI, confidence interval

P values < 0.05 are marked in bold