Table 1 Demographic characteristics, anthropometric measures, reproductive and lifestyle factors among participants of the Chinese Breast Cancer Screening Program (2013–2014)

From: Breast cancer risk factors and mammographic density among high-risk women in urban China

	All (n = 11478)		BI-RADS = 1 (n = 1206)		BI-RADS = 2 (n = 4216)		BI-RADS = 3 (n = 5736)		BI-RADS = 4 (n = 320)		P ^a
	n	%	n	%	n	%	n	%	n	%
Age
Mean (SD)	54.4	6.3	59.0	5.96	55.9	6.20	52.5	5.70	51.1	5.22	<1.0E-30
45-49	3016	26.3	84	7.0	729	17.3	2066	36.0	137	42.8	<1.0E-30
50–59	5760	50.2	534	44.3	2191	52.0	2881	50.2	154	48.1
60–69	2702	23.5	588	48.8	1296	30.7	789	13.8	29	9.1
Family history of breast and/or ovarian cancers
No	5797	50.5	581	48.2	2109	50.0	2939	51.3	168	52.7	0.05
1st or 2nd degree relatives^b	2205	19.2	226	18.7	814	19.3	1092	19.0	73	22.9
1st degree relatives with breast cancer <50 years	3472	30.3	399	33.1	1292	30.7	1703	29.7	78	24.5
Missing	4				1		2		1
Education
None-elementary	1369	11.9	325	26.9	564	13.4	460	8.0	20	6.3	<1.0E-30
Middle school	3405	29.7	402	33.3	1321	31.3	1615	28.2	67	20.9
High school	4054	35.3	336	27.9	1510	35.8	2083	36.3	125	39.1
College+	2650	23.1	143	11.9	821	19.5	1578	27.5	108	33.8
Body mass index (kg/m²)
Mean (SD)	24.1	3.00	25.7	3.11	24.4	2.97	23.7	2.85	22.3	2.86	<1.0E-30
<23	4188	38.1	231	20.3	1371	34.1	2392	43.3	194	62.6	<1.0E-30
23–24.9	2927	26.6	261	23.0	1073	26.7	1529	27.7	64	20.6
25+	3876	35.3	644	56.7	1582	39.3	1598	29.0	52	16.8
Missing	487		70		190		217		10
Weight (kg)
Mean (SD)	61.6	8.10	64.8	8.15	62.2	8.06	60.7	7.86	56.7	7.46	<1.0E-30
Missing	281		55		109		111		6
Height (cm)
Mean (SD)	159.8	4.52	159.2	4.72	159.8	4.54	160.0	4.44	159.5	4.57	6.1E-09
Missing	229		19		89		116		5
Age at menarche
<13	1334	11.7	112	9.3	438	10.4	727	12.7	57	17.9	1.4E-20
13–14	5245	45.8	469	39.1	1862	44.3	2749	48.0	165	51.7
15+	4874	42.6	620	51.6	1907	45.3	2250	39.3	97	30.4
Missing	25		5		9		10		1
Parity
Never	683	6.0	37	3.1	229	5.4	380	6.6	37	11.6	3.0E-09
Ever	10795	94.1	1169	96.9	3987	94.6	5356	93.4	283	88.4
Age at first full term birth^c
<25	3500	32.5	457	39.3	1276	32.1	1681	31.5	86	30.4	2.5E-04
25–26	3433	31.9	344	29.6	1277	32.1	1720	32.2	92	32.5
27–28	2136	19.8	217	18.6	796	20.0	1068	20.0	55	19.4
29+	1695	15.8	146	12.5	626	15.7	873	16.3	50	17.7
Missing	31		5		12		14		0
Breastfeeding^c
No breastfeeding	1870	17.3	174	14.9	645	16.2	982	18.3	69	24.4	2.5E-27
1–6 months	1866	17.3	156	13.3	699	17.5	952	17.8	59	20.8
7–12 months	4276	39.6	396	33.9	1564	39.2	2200	41.1	116	41.0
13 months+	2783	25.8	443	37.9	1079	27.1	1222	22.8	39	13.8
Menopausal status
Premenopausal	4100	35.7	154	12.8	1099	26.1	2665	46.5	182	56.9	<1.0E-30
Postmenopausal	7378	64.3	1052	87.2	3117	73.9	3071	53.5	138	43.1
Age at menopause among postmenopausal women
<49	2766	37.5	396	37.7	1134	36.4	1172	38.2	64	46.4	<1.0E-30
49–50	2613	35.4	347	33.0	1107	35.5	1116	36.4	43	31.2
51+	1997	27.1	308	29.3	876	28.1	782	25.5	31	22.5
Missing	2		1				1
Smoking
Never	10008	87.2	1075	89.1	3695	87.6	4957	86.4	281	87.8	0.01
Current	1264	11.0	105	8.7	435	10.3	689	12.0	35	10.9
Former	206	1.8	26	2.2	86	2.0	90	1.6	4	1.3
Alcohol consumption
Never	8456	73.7	920	76.3	3140	74.5	4154	72.4	242	75.6	0.03
Current	2640	23.0	257	21.3	935	22.2	1383	24.1	65	20.3
Former	381	3.3	28	2.3	141	3.3	199	3.5	13	4.1
Missing	1		1
Regular tea drinking
No	6087	57.9	568	51.5	2185	56.4	3137	59.9	197	68.4	1.9E-09
Yes	4419	42.1	534	48.5	1692	43.6	2102	40.1	91	31.6
Missing	972		104		339		497		32

^aResults from one-way analysis of variance (ANOVA) for continuous variables and χ² test for categorical variables
^bExcluding women with first-degree relatives with breast cancer <50 years
^cParous women only

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Table 1 Demographic characteristics, anthropometric measures, reproductive and lifestyle factors among participants of the Chinese Breast Cancer Screening Program (2013–2014)

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