Table I.

Description of study population

		Self-reported race/ethnicity
		NHW				Hispanic
		Controls		Cases		Controls		Cases
		N	%	N	%	N	%	N	%
Total sample		1586	37.9	1481	41.2	2597	62.1	2111	58.8
Study site	4-Corner’s	1322	83.4	1227	82.9	723	27.8	597	28.3
	Mexico	NA				994	38.3	816	38.7
	San Francisco Bay Area	264	16.7	254	17.2	880	33.9	698	33.1
Age (years)	<40	116	7.3	89	6.0	311	12.0	200	9.5
	40–49	408	25.7	409	27.6	831	32.0	713	33.8
	50–59	409	25.8	413	27.9	756	29.1	617	29.2
	60–69	350	22.1	361	24.4	526	20.3	430	20.4
	70+	303	19.1	209	14.1	173	6.7	151	7.2
	Mean	56.7		56.0		52.3		52.7
Menopausal statusa	Pre/Peri	494	31.5	489	33.5	1027	40.7	836	40.9
	Post	1076	68.5	970	66.5	1499	59.3	1210	59.1
Family history of breast cancerb (1°)	No	1290	84.5	1122	77.5	2326	91.8	1818	87.8
	Yes	237	15.5	326	22.5	208	8.2	252	12.2
% Native American ancestry	0–28	1578	99.5	1472	99.4	278	10.7	275	13.0
	29–70	7	0.4	7	0.5	1686	64.9	1393	66.0
	71–100	1	0.1	2	0.1	633	24.4	443	21.0
Educationc	<High school	79	5.0	73	4.9	1538	60.2	1098	52.6
	H.S. grad/GED	339	21.4	300	20.3	419	16.4	385	18.4
	>High school	1168	73.6	1107	74.8	597	23.4	606	29.0
BMId (kg/m2)	<25	700	44.4	678	45.9	453	17.6	492	23.5
	25–29	465	29.5	433	29.3	951	36.9	768	36.7
	30+	412	26.1	367	24.8	1172	45.5	832	39.8
Age at first birthe (years)	Nulliparous	249	15.7	261	17.7	181	7.0	229	11.0
	<20	199	12.6	178	12.0	825	31.9	508	24.3
	20–24	609	38.5	522	35.3	922	35.7	732	35.0
	25–29	342	21.6	333	22.5	451	17.5	359	17.2
	30+	184	11.6	184	12.5	204	7.9	264	12.6
Number of full-term	Nulliparous	249	15.7	261	17.6	181	7.0	229	10.9
	1–2	638	40.3	646	43.7	790	30.5	786	37.2
Pregnanciesf	3–4	529	33.4	462	31.2	997	38.4	738	35.0
	5+	167	10.6	111	7.5	626	24.1	358	17.0
Alcohol consumptiong (gm/day)	None	793	50.8	691	46.9	2151	83.5	1707	81.1
	<5	381	24.4	382	25.9	244	9.5	210	10.0
	5 up to 10	156	10.0	166	11.3	100	3.9	109	5.2
	10+	232	14.9	236	16.0	81	3.1	78	3.7
Vigorous-intensity physical activityh (hours/week)	4 Corner’s: None	461	34.9	440	35.9	319	44.1	287	48.1
	Meani	2.2		2.1		1.8		2.3
	Mexico: None					827	83.2	555	68.1
	Meani					8.8		4.5
	California: None	142	53.8	131	51.6	682	77.5	523	74.9
	Meani	4.8		4.0		4.3		4.3

^a174 observations without menopausal status.

^b196 observations without family history of breast cancer data.

^c66 observations without education data.

^d52 observations without BMI measurements.

^e39 observations without age at first birth data.

^f7 observations without number of full-term pregnancies data.

^gBased on long-term alcohol consumption except for a subgroup of California subjects for whom data on alcohol consumption were available only for reference year; 58 observations without alcohol data.

^h1 observation without information on physical activity.

ⁱExcludes subjects with no vigorous physical activity a week.