European Ancestry Is Positively Associated with Breast Cancer Risk in Mexican Women

Laura Fejerman; Isabelle Romieu; Esther M. John; Eduardo Lazcano-Ponce; Scott Huntsman; Kenneth B. Beckman; Eliseo J. Pérez-Stable; Esteban González Burchard; Elad Ziv; Gabriela Torres-Mejía

doi:10.1158/1055-9965.EPI-09-1193

DOI: 10.1158/1055-9965.EPI-09-1193 Published April 2010

Article Figures & Data

Tables

Table 1.

Characteristics of Mexican women by case-control status, 2004 to 2007

	Cases (n = 846)	Controls (n = 1035)	P^*
Age (y)^†	52.0 (10)	51.1 (9)	0.02
BMI^† premenopausal women	28.2 (5)	30.1 (5)	<0.01
BMI^† postmenopausal women	30.2 (6)	30.8 (5)	0.06
Age at menarche (y)^†	12.8 (2)	12.8 (2)	0.21
No. of full-term pregnancies^†	3.0 (2)	3.7 (2)	<0.01
Ever breast-fed (%)^‡	86.0	89.5	0.03
Family history of breast cancer (%)	6.6	3.8	0.004
Benign breast disease (%)	14.7	7.51	<0.01
Postmenopausal HRT use (%)^§	21.9	14.5	<0.01
Postmenopausal (%)	57.6	55.5	0.37
Alcohol consumption (ever in past year/never; %)	19.3	10.9	<0.01
Socioeconomic status (%)			<0.01
Low	25.9	32.6
Middle	24.4	34.0
High	49.7	33.4
Education (%)			<0.01
None	6.6	8.5
Some elementary school	19.5	26.3
Completed elementary school	30.4	29.6
High school graduate	25.8	25.5
College graduate	8.6	5.9
Postgraduate studies	9.0	4.2
Caloric intake (kcal/d)^†	2,225.4 (789)	1,935.4 (673)	<0.01
Percent European ancestry^†	35.9 (19)	31.8 (18)	<0.01
Percent indigenous American ancestry^†	59.5 (20)	64.1 (20)	<0.01
Percent African ancestry^†	4.5 (6)	4.1 (5)	0.11

Abbreviation: HRT, hormone replacement therapy.

↵*P values are for bivariate Fisher's exact tests in 2 × 2 tables (for categorical variables) and for t tests comparing mean values between cases and controls (for continuous variables).
↵^†Mean (SD).
↵^‡Women who had at least one full-term pregnancy.
↵^§Proportion of menopausal women that use hormone replacement therapy.

Table 2.

Characteristics of Mexican controls by European genetic ancestry, 2004 to 2007

	European genetic ancestry				P^*
	<25	26-50	51-75	76-100	P^*
Age (y)^†	51.9 (9)	51.3 (9)	50.9 (9)	51.3 (10)	0.954
BMI premenopausal women^†	29.7 (5)	30.3 (5)	30.7 (6)	30.8 (5)	0.592
BMI postmenopausal women^†	30.4 (5)	31.3 (5)	30.2 (5)	34.7 (8)	0.070
Age at menarche (y)^†	12.9 (2)	12.8 (2)	12.9 (2)	13.2 (2)	0.332
No. of full-term pregnancies^†	3.6 (2)	3.9 (3)	3.4 (2)	4.1 (3)	0.073
Ever breast-fed (%)^‡	90.7	89.7	85.0	100.0	0.278
Family history of breast cancer (%)	2.4	3.5	7.4	10.0	0.034
Benign breast disease (%)	6.8	8.0	7.4	10.0	0.768
Postmenopausal HRT use (%)^§	14.7	12.7	21.1	16.7	0.266
Postmenopausal (%)	54.7	56.5	53.3	60.0	0.891
Alcohol consumption (ever in past year/never; %)	11.7	10.1	12.2	11.1	0.761
Socioeconomic status (%)					<0.001
Low	42.3	28.0	25.0	0.0
Middle	31.5	36.9	29.7	33.3
High	26.2	34.9	45.3	66.7
Education (%)					<0.001
None	11.8	7.3	4.4	0.0
Some elementary school	32.4	24.6	17.8	0.0
Completed elementary school	24.9	29.6	40.7	50.0
High school graduate	23.3	27.8	22.2	30.0
College graduate	5.1	5.8	8.9	0.0
Postgraduate studies	2.4	4.8	5.9	20.0
Caloric intake (kcal/d)^†	1819.4 (584)	1955.9 (682)	2132.1 (761)	2413.4 (1070)	<0.001

↵*P values are for bivariate Fisher's exact tests in 2 × 2 tables (for categorical variables) and for ANOVA tests (for continuous variables).
↵^†Mean (SD).
↵^‡Women who had at least one full-term pregnancy.
↵^§Proportion of menopausal women that use hormone replacement therapy.

Table 3.

Characteristics of Mexican controls by socioeconomic status, 2004 to 2007

	Socioeconomic status			P^*
	Low	Medium	High	P^*
European ancestry (%)				<0.001
0-25	47.4	33.8	28.7
26-50	42.7	54.0	51.9
51-75	9.9	11.3	17.5
76-100	0.0	0.9	1.8
Age (y)^†	51.1 (10)	51.5 (9)	50.5 (8)	0.391
BMI^† premenopausal women	30.5 (6)	30.4 (5)	29.3 (5)	0.111
BMI^† postmenopausal women	30.6 (5)	31.0 (5)	30.5 (5)	0.616
Age at menarche (y)^†	12.9 (2)	12.9 (2)	12.7 (2)	0.040
No. of full-term pregnancies^†	3.5 (2)	3.2 (2)	2.6 (2)	<0.001
Ever breast-fed (%)^‡	88.5	93.2	85.3	0.005
Family history of breast cancer (%)	2.2	4.7	4.5	0.142
Benign breast disease (%)	4.4	7.8	10.1	0.020
Postmenopausal HRT use (%)^§	9.9	15.3	15.4	0.222
Postmenopausal (%)	53.6	60.2	51.1	0.047
Alcohol consumption (ever in past year/never; %)	7.5	9.8	13.8	0.03
Education (%)				<0.001
None	12.1	10.7	3.6
Some elementary school	36.2	28.8	13.9
Completed elementary school	28.8	30.9	28.4
High school graduate	20.7	23.7	32.3
College graduate	2.2	3.9	11.2
Postgraduate studies	0.0	2.1	10.6
Caloric intake (kcal/d)^†	1773.9 (558)	1909.6 (630)	2034.0 (711)	<0.001

↵*P values are for bivariate Fisher's exact tests in 2 × 2 tables (for categorical variables) and for ANOVA tests (for continuous variables).
↵^†Mean (SD).
↵^‡Women who had at least one full-term pregnancy.
↵^§Proportion of menopausal women that use hormone replacement therapy.

Table 4.

Association between genetic ancestry and breast cancer risk in women residing in Mexico, 2004 to 2007

	Odds ratio	95% CI	P
Unadjusted model (n = 1,881; 846 cases and 1,035 controls)
European ancestry (%)^*			<0.001 Trend
26-50	1.16	0.94-1.43	0.171
51-75	1.80	1.35-2.39	<0.001
76-100	3.22	1.46-7.11	0.004
Continuous^†	1.37	1.21-1.55	<0.001
Continuous^† Mexico city (n = 1,128)	1.45	1.24-1.69	<0.001
Continuous^† Monterrey (n = 452)	1.27	0.96-1.70	0.096
Continuous^† Veracruz (n = 301)	1.16	0.82-1.62	0.395
Unadjusted model for individuals with no missing data (n = 1540; 685 cases and 855 controls)
European ancestry (%)^*			<0.001 Trend
26-50	1.10	0.87-1.40	0.409
51-75	1.79	1.35-2.39	<0.001
76-100	3.34	1.39-8.03	0.007
Continuous^†	1.36	1.19-1.57	<0.001
Adjusted by socioeconomic status (n = 1,787; 796 cases and 991 controls)
European ancestry (%)^*			<0.001 Trend
26-50	1.13	0.91-1.41	0.275
51-75	1.76	1.31-2.36	<0.001
76-100	2.89	1.25-6.67	0.013
Continuous^†	1.34	1.17-1.53	<0.001
Socioeconomic status	1.29	1.13-1.46	<0.001
Adjusted by socioeconomic status and education (n = 1,786; 795 cases and 991 controls)
European ancestry (%)^*			<0.001 Trend
26-50	1.09	0.87-1.36	0.438
51-75	1.67	1.24-2.26	0.001
76-100	2.68	1.16-6.20	0.021
Continuous^†	1.30	1.13-1.48	<0.001
Socioeconomic status	1.18	1.05-1.37	0.008
Education	1.16	1.07-1.26	<0.001
Fully adjusted model (n = 1,540; 685 cases and 855 controls)
European ancestry (%)^*			0.044 Trend
26-50	1.01	0.78-1.30	0.962
51-75	1.35	0.96-1.91	0.087
76-100	2.44	0.94-6.35	0.067
Continuous^†	1.20	1.03-1.41	0.019
Age at diagnosis (y)	1.04	1.02-1.07	<0.001
BMI (kg/m²)	0.95	0.93-0.97	<0.001
No. of full-term pregnancies (0 to ≥7)	0.85	0.78-0.92	<0.001
Breast-feeding (ever/never)	0.96	0.65-1.42	0.853
Benign breast disease	2.11	1.45-3.08	<0.001
Family history of breast cancer	1.70	1.03-2.79	0.036
Moderate physical activity (h/wk)	0.97	0.97-0.98	<0.001
Education	1.05	0.93-1.18	0.438
Socioeconomic status	1.01	0.86-1.18	0.919
Alcohol consumption (ever in past year)	1.78	1.29-2.45	0.001
Daily caloric intake (per 500 kcal unit)	1.40	1.28-1.52	<0.001
HRT/menopause^‡
Premenopausal/HRT	1.02	0.41-2.53	0.964
Postmenopausal/no HRT	0.80	0.54-1.20	0.281
Premenopausal/no HRT	0.93	0.58-1.47	0.740
Age at first full-term pregnancy (y)^§
21-30	0.98	0.76-1.28	0.908
≥31	1.56	0.91-2.66	0.103
No full-term pregnancy	1.00	0.53-1.91	0.991
Age at menarche (y)	0.93	0.87-1.00	0.043