Table 4.

Treatments of the patients with breast cancer

Characteristics	Total (N = 15,389)		Premenopausal (N = 8395)		Postmenopausal (N = 6994)		P value
	N	%	N	%	N	%
Chemotherapy
Yes	12,437	80.77	7141	85.06	5296	75.72	<0.0001a
No	2294	14.90	960	11.44	1334	19.07
Missing data	668	4.34	294	3.50	374	5.35
Radiotherapy
Yes	2624	17.04	1705	20.31	919	13.14	<0.0001a
No	12,058	78.31	6373	75.91	5685	81.28
Missing data	707	4.59	317	3.78	390	5.58
Anti‐HER2 therapy
Yes	136	0.88	75	0.89	61	0.87	0.978a
No	14,571	94.63	8018	95.51	6553	93.69
Missing data	682	4.43	302	3.60	380	5.43
Endocrine therapy
Yes	4093	26.58	2499	29.77	1594	22.79	<0.0001a
No	10,584	68.74	5574	66.40	5010	71.63
Missing data	712	4.62	322	3.84	390	5.58
Type of surgery
Modified radical mastectomy	11,467	74.47	6061	72.20	5406	77.29	<0.0001a
Breast‐conserving surgery	1582	10.27	986	11.75	596	8.52
Simple mastectomy	793	5.15	451	5.37	342	4.89
Radical mastectomy	196	1.27	115	1.37	81	1.16
Extensive radical mastectomy	103	0.67	58	0.69	45	0.64
Breast reconstruction	380	2.47	314	3.74	66	0.94
Missing data	868	5.64	410	4.88	458	6.55
Axillary lymph node dissection
Yes	13,065	84.85	7145	85.11	5920	84.64	0.058a
No	1575	10.23	901	10.73	674	9.64
Missing data	749	4.86	349	4.16	400	5.72
Level of axillary lymph node dissection
Level I, II	9504	61.72	5220	62.18	4284	61.25	0.485a
Level III	1867	12.12	1009	12.02	858	12.27
Missing data	4018	26.09	2166	25.80	1852	26.48

^aChi‐square test.