Table 3: Distribution of socioeconomic and gynecological variables in breast cancer women (cases) and their control subjects, from Midwest of Brazil (2008–2010).

Variable*Cases ( 𝑛 = 9 3 )Controls ( 𝑛 = 1 8 6 )Crude OR (95% CI) 𝑃 value**
𝑛 % 𝑛 %

Age (years)
 <504043.017238.711.00
 ≥505356.9911461.290.84 (0.50–1.39)0.490
Education level
 Did not study1212.9094.841.00
 ≤Primary education5963.4413371.500.33 (0.13–0.83)0.019
 ≥High school2223.664423.660.37 (0.14–1.02)0.056
Per capita income (US$)
 >1/2 Brazilian minimum wage4346.24105601.00
 ≤1/2 Brazilian minimum wage5053.767040.001.74 (1.05–2.89)0.032
Area of residence
 Urban6783.7515596.271.00
 Rural1316.2563.735.01 (1.82–13.74)0.002
Bearing children
 Yes8995.7016990.861.00
 No44.30179.140.45 (0.14–1.37)0.158
Number of children
 Nulliparity44.30179.141.00
 1–3 children6266.6710858.062.44 (0.78–7.58)0.123
 >3 children2729.036132.801.88 (0.58–6.12)0.294
Total breastfeeding (months)
 Never44.3031.641.00
 ≤61212.902111.480.43 (0.08–2.25)0.316
 7–121010.752010.930.37 (0.07–2.01)0.252
 >126772.0413975.960.36 (0.79–1.66)0.191
Age at first pregnancy (years)
 ≤308393.2615592.811.00
 >3066.74127.190.93 (0.34–2.58)0.895
Age at menarche (years)
 <12 (early)1314.942815.301.00
 ≥12 (usual)7485.0615584.701.02 (0.50–2.09)0.939
Age at menopause (years)
 <55 (usual)3491.8911192.501.00
 ≥55 (late)38.1197.501.09 (.28–4.25)0.903
Family history of cancer
 No3032.269450.541.00
 Yes6367.749249.462.14 (1.27–3.61)0.004
Family history of breast cancer (mother/sisters)
 No8591.4018297.851.00
 Yes88.6042.154.28 (1.25–14.61)0.020

OR: odds ratio and CI: confidence interval.
*Per capita income: Brazilian minimum wage corresponds to approximately US$ 300; 11 control subjects did not indicate their per capita income; area of residence: information is unavailable for 13 cases and 25 controls; total breastfeeding: 3 controls did not indicate their breastfeeding time; age at first pregnancy: 4 cases and 19 controls did not have children or did not indicate their age at first pregnancy; age at menarche: 6 cases and 3 controls did not indicate their age at menarche; age at menopause: 12 cases and 11 controls did not indicate their age at menopause; 44 cases and 55 controls were premenopausal.
**Wald statistic.