Table 3. Factors associated with ipsilateral breast tumor relapse (IBTR) among patients who received accelerated whole breast irradiation (AWBI) and conventional whole breast irradiation (CWBI).

	AWBI+CWBI (N=660)	AWBI (N=330)	CWBI (N=330)
	5-year event rate (%)	Log-rank P	5-year event rate (%)	Log-rank P	5-year event rate (%)	Log-rank P
Total	1.2	-	0.8	-	1.8	-
Age (y)	0.83	0.83	0.69
<50	1.2		0.6		1.8
≥50	1.2		0.7		1.8
Histology		0.26		0.51	0.34
Ductal	1.4		0.7		2.0
Others		0			0		0
Pathologic T stage		0.65		0.37		0.98
T1	1.1		0.5	0.8
T2	1.5		1.0		4.1
Pathologic N stage		0.26	0.06	0.99
N0	1.1		0.4	1.8
N1	2.0		2.1		2.1
Resection margin		0.53		0.74	0.58
>1mm	1.3		0.7		1.9
≤1mm	0		0		0
Tumor grade		0.01		0.08		0.10
Low-Intermediate	0.3		0		0.5
High	2.9		1.9		3.8
Molecular subtype		0.35		0.76		0.37
Luminal	0.8		0.4		1.3
Non-luminal	2.5		1.6		3.2
Ki-67 index		0.07		0.08		0.06
<14%	0.9		0		1.4
≥14%	2.2		1.4		6.0
Chemotherapy		0.67		0.87		0.46
Yes	1.2		0.4		3.1
No	1.4		1.4		0
Hormone therapy		0.28		0.13		0.95
Yes	1.2		0.4		1.3
No	1.3		1.5		3.3