. Author manuscript; available in PMC: 2009 Sep 30.

Published in final edited form as: Nat Genet. 2009 Feb 15;41(3):324–328. doi: 10.1038/ng.318

Table 1.

Distribution of demographic characteristics and known breast cancer risk factors for cases and controls included in the study

	Stage I		Stage II		Stage III		NBHS
	Cases (n=1,505)	Controls (n=1,522)	Cases (n=1,554)	Controls (n=1,576)	Cases (n=3,472)	Controls (n=900)	Cases (n=1,591)	Controls (n=1,466)
Demographic Factors^a
Age (yr)	46.9 ± 7.2	47.0 ± 7.5	52.4 ± 8.5	52.8 ± 9.0	54.9 ± 10.5	54.9 ± 8.6	54.8 ± 10.2	52.2 ± 11.0^b
Education ≥ high school (%)	47.5	47.8	56.9	43.5^b	52.2	39.9^b	94.8	96.5
Reproductive Risk Factors^a
Age at menarche (yr)	14.4 ± 1.6	14.7 ± 1.7^b	14.4 ± 1.7	14.7 ± 1.8^b	14.4 ± 1.7	14.8 ± 1.8^b	12.6 ± 2.6	12.8 ± 4.2
Postmenopausal (%)	26.5	30.4^b	52.2	57.7^b	53.6	61.8^b	65.3	59.0 ^b
Age at menopause^c	47.9 ± 4.7	47.1 ± 5.0^b	48.7 ± 4.3	48.5 ± 4.5	49.1 ± 4.3	49.1 ± 3.6	46.2 ± 8.5	45.3 ± 8.7^b
Number of live births	1.4 ± 0.7	1.4 ± 0.8	1.4 ± 0.7	1.5 ± 0.9^b	1.6 ± 1.0	1.8 ± 1.1^b	2.7 ± 0.7	2.7 ± 0.7
Age at first live birth (yr)^d	26.8 ± 3.8	26.3 ± 3.6^b	26.1 ± 3.7	25.5 ± 4.0^b	26.9 ± 4.0	25.3 ± 4.1^b	24.3 ± 5.3	24.6 ± 5.2
Used HRT (%)^e	2.2	2.2	4.1	2.9	3.8	4.6	51.1	56.5^b
Other Risk factors^a
Had breast cancer family history (%)	5.4	3.2^b	4.0	2.5^b	5.7	2.3^b	19.7	14.1^b
Prior BBD diagnosis (%)^f	10.3	5.5^b	9.4	5.3^b	N/A	N/A	49.3	33.4^b
Body mass index	23.6 ± 3.4	23.2 ± 3.3^b	23.8 ± 3.2	23.5 ± 3.2^b	24.2 ± 3.5	23.8 ± 3.5^b	27.2 ± 7.1	26.7 ± 6.9
Waist-to-hip ratio	0.81 ± 0.05	0.80 ± 0.06^b	0.83 ± 0.05	0.82 ± 0.06^b	0.84 ± 0.05	0.82 ± 0.06^b	NA	NA

Unless otherwise specified, mean (sd) are presented.

P ≤ 0.05 for case-control comparisons.

Among postmenopausal women.

Among parous women.

HRT: Hormone Replacement Therapy

BBD defined as breast fibroadenoma in Stages I and II and breast cysts or lumps in the NBHS.