Table 4.

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

Odds ratio95% CIP
Unadjusted model (n = 1,881; 846 cases and 1,035 controls)
    European ancestry (%)*<0.001 Trend
        26-501.160.94-1.430.171
        51-751.801.35-2.39<0.001
        76-1003.221.46-7.110.004
        Continuous1.371.21-1.55<0.001
        Continuous Mexico city (n = 1,128)1.451.24-1.69<0.001
        Continuous Monterrey (n = 452)1.270.96-1.700.096
        Continuous Veracruz (n = 301)1.160.82-1.620.395
Unadjusted model for individuals with no missing data (n = 1540; 685 cases and 855 controls)
    European ancestry (%)*<0.001 Trend
        26-501.100.87-1.400.409
        51-751.791.35-2.39<0.001
        76-1003.341.39-8.030.007
        Continuous1.361.19-1.57<0.001
Adjusted by socioeconomic status (n = 1,787; 796 cases and 991 controls)
    European ancestry (%)*<0.001 Trend
        26-501.130.91-1.410.275
        51-751.761.31-2.36<0.001
        76-1002.891.25-6.670.013
        Continuous1.341.17-1.53<0.001
    Socioeconomic status1.291.13-1.46<0.001
Adjusted by socioeconomic status and education (n = 1,786; 795 cases and 991 controls)
    European ancestry (%)*<0.001 Trend
        26-501.090.87-1.360.438
        51-751.671.24-2.260.001
        76-1002.681.16-6.200.021
        Continuous1.301.13-1.48<0.001
    Socioeconomic status1.181.05-1.370.008
    Education1.161.07-1.26<0.001
Fully adjusted model (n = 1,540; 685 cases and 855 controls)
    European ancestry (%)*0.044 Trend
        26-501.010.78-1.300.962
        51-751.350.96-1.910.087
        76-1002.440.94-6.350.067
        Continuous1.201.03-1.410.019
    Age at diagnosis (y)1.041.02-1.07<0.001
    BMI (kg/m2)0.950.93-0.97<0.001
    No. of full-term pregnancies (0 to ≥7)0.850.78-0.92<0.001
    Breast-feeding (ever/never)0.960.65-1.420.853
    Benign breast disease2.111.45-3.08<0.001
    Family history of breast cancer1.701.03-2.790.036
    Moderate physical activity (h/wk)0.970.97-0.98<0.001
    Education1.050.93-1.180.438
    Socioeconomic status1.010.86-1.180.919
    Alcohol consumption (ever in past year)1.781.29-2.450.001
    Daily caloric intake (per 500 kcal unit)1.401.28-1.52<0.001
    HRT/menopause
        Premenopausal/HRT1.020.41-2.530.964
        Postmenopausal/no HRT0.800.54-1.200.281
        Premenopausal/no HRT0.930.58-1.470.740
    Age at first full-term pregnancy (y)§
        21-300.980.76-1.280.908
        ≥311.560.91-2.660.103
        No full-term pregnancy1.000.53-1.910.991
    Age at menarche (y)0.930.87-1.000.043
  • *European ancestry between 0% and 25% is the reference.

  • Odds ratio is for every 25% increase in European ancestry.

  • Postmenopausal and hormone replacement therapy is the reference.

  • §First full-term pregnancy before the age of 20 years is the reference.