Research Article
A Matched Case-Control Study of Risk Factors for Breast Cancer Risk in Vietnam
Table 5
Conditional logistic regression analysis to estimate the odds (odd ratio, OR) of breast cancer in premenopausal women.
| | Cases | Controls | Unadjusted OR | Adjusted OR | OR | 95% CI | | OR | 95% CI | |
| Reproductive factors | | | | | | | | | Age at menarche | 15.8 | 15.7 | 1.03 | 0.92–1.14 | 0.64 | 1 | 0.89–1.15 | 0.84 | | | | | | | | | | 0 | 10 (5.3%) | 4 (2.1%) | 1 | | | 1 | | | 1 | 16 (8.2%) | 7 (3.6%) | 0.83 | 0.17–4.05 | 0.82 | 1.25 | 0.24–6.63 | 0.05 | 2 | 110 (56.1%) | 96 (49.0%) | 0.38 | 0.10–1.47 | 0.16 | 0.43 | 0.11–1.72 | 0.47 | 3 | 39 (19.9%) | 64 (32.7%) | 0.19 | 0.05–0.74 | 0.02 | 0.22 | 0.05–0.95 | 0.004 | 4+ | 14 (7.1%) | 24 (12.2%) | 0.25 | 0.06–1.09 | 0.06 | 0.28 | 0.06–1.26 | 0.09 | Age at 1st parity | 24.2 | 23.7 | 1.03 | 0.97–1.09 | 0.33 | | | | Total months breastfeeding | 36.1 | 37.4 | 1 | 0.99–1.02 | 0.81 | | | |
| Anthropometric factors | | | | | | | | | BMI at age | | | | | | | | | <18 kg/m2 | 42 (21.5%) | 60 (31.6%) | 1 | | | 1 | | | 18–20 kg/m2 | 64 (32.8%) | 80 (42.1%) | 1.16 | 0.69–1.94 | 0.44 | 1.33 | 0.76–2.34 | 0.24 | >20 kg/m2 | 89 (45.6%) | 50 (26.3%) | 2.73 | 1.56–4.79 | 0.0006 | 2.801 | 1.51–5.20 | 0.001 |
| Hormonal factors | | | | | | | | | OCP | | | | | | | | | No | 173 (89.2%) | 184 (94.9%) | 1 | | | 1 | | | Yes | 21 (10.8%) | 10 (5.2%) | 2.2 | 1.01–4.89 | 0.05 | 2.11 | 0.89–5.01 | 0.09 |
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denotes the variables used for multivariate analysis to calculate the adjusted OR.
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