Table 1. Baseline characteristics before and after propensity score matching (PSM).

Variables	Before PSM			After PSM
	No-PMRT (n = 108)	PMRT (n = 185)	P	No-PMRT (n = 94)	PMRT (n = 94)	P
Age			0.921			0.483
<40	14 (12.96%)	27 (14.59%)		11 (11.70%)	11 (11.70%)
40–60	59 (54.63%)	98 (52.97%)		56 (59.57%)	63 (67.02%)
>60	35 (32.41%)	60 (32.43%)		27 (28.72%)	20 (21.28%)
Race			0.507			0.270
White	82 (75.93%)	151 (81.62%)		69 (73.40%)	78 (82.98%)
Black	16 (14.81%)	21 (11.35%)		16 (17.02%)	11 (11.70%)
Other	10 (9.26%)	13 (7.03%)		9 (9.57%)	5 (5.32%)
Marital status			0.007			0.127
Married	44 (40.74%)	109 (58.92%)		40 (42.55%)	53 (56.38%)
Unmarried	56 (51.85%)	70 (37.84%)		46 (48.94%)	37 (39.36%)
Unknown	8 (7.41%)	6 (3.24%)		8 (8.51%)	4 (4.26%)
Grade			0.081			0.079
Grade I/II	24 (22.22%)	51 (27.57%)		19 (20.21%)	30 (31.91%)
Grade III/IV	69 (63.89%)	94 (50.81%)		60 (63.83%)	45 (47.87%)
Unknown	15 (13.89%)	40 (21.62%)		15 (15.96%)	19 (20.21%)
AJCC stage			0.088			0.082
IIIA	62 (57.41%)	124 (67.03%)		52 (55.32%)	61 (64.89%)
IIIB	17 (15.74%)	31 (16.76%)		13 (13.83%)	17 (18.09%)
IV	29 (26.85%)	30 (16.22%)		29 (30.85%)	16 (17.02%)
Breast Subtype			0.976			0.805
Her2-/HR+	37 (34.26%)	65 (35.14%)		30 (31.91%)	31 (32.98%)
Her2+/HR-	17 (15.74%)	32 (17.30%)		15 (15.96%)	11 (11.70%)
Her2+/HR+	22 (20.37%)	38 (20.54%)		20 (21.28%)	26 (27.66%)
Triple Negative	25 (23.15%)	41 (22.16%)		23 (24.47%)	20 (21.28%)
Unknown	7 (6.48%)	9 (4.86%)		6 (6.38%)	6 (6.38%)
Surgery			0.069			0.154
Simple Mastectomy	33 (30.56%)	39 (21.08%)		24 (25.53%)	16 (17.02%)
Radical mastectomy	75 (69.44%)	146 (78.92%)		70 (74.47%)	78 (82.98%)
Chemotherapy			<0.001			1.000
No/unknown	16 (14.81%)	3 (1.62%)		3 (3.19%)	3 (3.19%)
Yes	92 (85.19%)	182 (98.38%)		91 (96.81%)	91 (96.81%)

Notes.

Abbreviations

HoR

Hormone receptor

PSM

propensity score matching

PMRT

postmastectomy radiotherapy