Table 1.

Baseline characteristics of patients with chemotherapy and no-chemotherapy

Characteristics		No-Chemotherapy (n = 2574)		Chemotherapy (n = 2122)		Total (n = 4696)		Pc
		No	%	No	%	No	%
Median follow-up (months) (IQR)		27(12–49)		27(12–47)		27(12–48)
Age (years)	70–79	1257	48.8	1836	86.5	3093	65.9	< 0.001
	80 +	1317	51.2	286	13.5	1603	34.1
Race	White	2003	77.8	1636	77.1	3639	77.5	0.238
	Black	383	14.9	348	16.4	731	15.6
	Othera	188	7.3	138	6.5	326	6.9
Marital status	Married	959	37.3	1085	51.1	2044	43.5	< 0.001
	Not marriedb	1615	62.7	1037	48.9	2652	56.5
Grade	I and II	707	27.5	388	18.3	1095	23.3	< 0.001
	III	1867	72.5	1734	81,7	3601	76.7
AJCC stage	I	1317	51.2	706	33.3	2023	43.1	< 0.001
	II	960	37.3	999	47.1	1959	41.7
	III	297	11.5	417	8.9	714	15.2
Tumor status	T1	1435	55.7	910	42.9	2345	49.9	< 0.001
	T2	876	34.0	919	43.3	1795	38.2
	T3	150	5.8	148	7.0	298	6.3
	T4	113	4.4	145	6.8	258	5.5
Nodal status	N0	2039	79.2	1290	60.8	3329	70.9	< 0.001
	N1	357	13.9	556	26.2	913	19.4
	N2	104	4.0	172	8.1	276	5.9
	N3	74	2.9	104	4.9	178	3.8
Surgery approach	No surgery	150	5.8	107	5.0	257	5.5	0.239
	Mastectomy and BCS	2424	94.2	2015	95.0	4439	94.5
Radiation status	Yes	1013	39.4	1179	55.6	2192	46.7	< 0.001
	No	1561	60.6	943	44.4	2504	53.3

Abbreviation: AJCC American Joint Committee on Cancer, BCS Breast-conserving surgery, IQR Interquartile range

^aOther includes American Indian/Alaskan native and Asian/Pacific Islander and Unknown

^bNot married includes divorced, separated, single (never married), unmarried or domestic partner, and widowed

^cThe P value of the Chi-square test was calculated between the chemotherapy and no-chemotherapy groups, and bold type indicates significance