Table 1.

Baseline characteristics of postmenopausal breast cancer cases and controls ^a

	Cases (n=713)		Controls (n=713)
	No.	%	No.	%	OR	(95% CI) b
Matching variables
Mean age at blood draw, years (Mean (SD))	67.9	(7.5)	67.9	(7.5)	-
Ethnicity					-
White	151	21.2	151	21.2
African-American	107	15.0	107	15.0
Native Hawaiian	68	9.5	68	9.5
Japanese-American	254	35.6	254	35.6
Latino	133	18.7	133	18.7
Hormone replacement therapy use at blood draw	241	33.8	241	33.8	-
Non-matching variables c
Years of education, years
≤12	283	39.7	276	38.7	1.00	-
>12	427	59.9	434	60.9	0.95	(0.76 – 1.20)
Body mass index, kg/m2
<25.0	320	44.9	382	53.6	1.00	-
25.0–29.9	250	35.1	199	27.9	1.60	(1.24 – 2.08)
≥30.0	129	18.1	122	17.1	1.37	(1.00 – 1.88)
Tobacco smoking
Never	388	54.4	408	57.2	1.00	-
Ever	318	44.6	298	41.8	1.13	(0.91 – 1.40)
Alcohol drinking
No	415	58.2	441	61.9	1.00	-
Yes	281	39.4	256	35.9	1.19	(0.95 – 1.50)
Family history of breast cancer
No	571	80.1	596	83.6	1.00	-
Yes	109	15.3	84	11.8	1.38	(1.00 – 1.89)
Age at menarche, years
≤12	366	51.3	360	50.5	1.00	-
>12	336	47.1	351	49.2	0.93	(0.75 – 1.15)
Age at menopause, years
<45	191	26.8	191	26.8	1.00	-
45–49	143	20.1	170	23.8	0.85	(0.62 – 1.15)
≥50	379	53.2	352	49.4	1.09	(0.84 – 1.42)
Live births
Never	87	12.2	71	10.0	1.00	-
1 birth	79	11.1	79	11.1	0.80	(0.51 – 1.25)
2–3 births	343	48.1	321	45.0	0.86	(0.60 – 1.22)
≥4 births	200	28.1	238	33.4	0.67	(0.46 – 0.97)

Abbreviation: SD, standard deviation; OR, odds ratio; CI, confidence interval.

^aData are presented as number and percentage unless otherwise indicated.

^bModeled through conditional logistic regression.

^cSum of the number of subjects is not consistent with the total number because of missing information.