Ipsilateral breast tumor recurrence in early stage breast cancer patients treated with breast conserving surgery and adjuvant radiation therapy: Concordance of biomarkers and tumor location from primary tumor to in-breast tumor recurrence

Table 3 Results of univariate Cox model assessing the association of clinical variables with risk of the first ipsilateral breast tumor recurrence

Clinical variable	Hazard ratio (95%CI)	P value
Patient age (continuous)	1.004 (0.98-1.02)	0.73
ER negative	1	-
ER positive	0.53 (0.26-1.11)	0.093
PR negative	1	-
PR positive	0.75 (0.38-1.50)	0.423
Tumor grade: Low	1	-
Tumor grade: Intermediate	0.791 (0.25-2.5)	0.689
Tumor grade: High	1.624 (0.54-4.8)	0.385
Margins negative	1	-
Margins positive	0.793 (0.36-1.75)	0.565
No chemotherapy	1	-
Chemotherapy up-front	1.282 (0.63-2.6)	0.499
No endocrine therapy up-front	1	-
Endocrine therapy up-front	0.362 (0.18-0.73)	0.004
Biomarker not concordant	1	-
Biomarker concordant	1.04 (0.95-1.10)	0.92
Location not concordant	1	-
Location concordant	1.265 (0.63-2.53)	0.506
Size < 1.5 cm	1	-
Size ≥ 1.5 cm	0.442 (0.22-0.90)	0.023
Invasive primary tumors
LVI none	1	-
LVI present	0.617 (0.20-1.92)	0.404
HER2 negative/equivocal	1	-
HER2 positive	0.837 (0.28-2.55)	0.754
Ki-67 (continuous)	1.002 (0.99-1.02)	0.745

IBTR: Ipsilateral breast tumor recurrence; HR: Hormone receptor; ER: Estrogen receptor; PR: Progesterone receptor; LVI: Lymphovascular invasion.