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Table 7 Odds ratios (ORs) for breast cancer and smoking in relation to the CYP1A1 genotype at the M4 locus (white women only)
| M4 genotypesa | wt genotypeb | |||
|---|---|---|---|---|
| Cases/controls | OR (95% CI)c | Cases/controls | OR (95% CI)c | |
| Active smoking status | ||||
| Never | 24/16 | Reference | 177/190 | Reference |
| Former | 13/8 | 1.2 (0.4–3.6) | 123/116 | 1.1 (0.8–1.6) |
| Current | 2/16 | 0.1 (0.0–0.4) | 78/71 | 1.2 (0.8–1.7) |
| Number of cigarettes (pack/day) | ||||
| Never | 24/16 | Reference | 177/190 | Reference |
| ≤ 1 | 8/14 | 0.4 (0.1–1.2) | 128/111 | 1.2 (0.9–1.7) |
| > 1 | 7/10 | 0.5 (0.2–1.6) | 71/75 | 1.0 (0.7–1.5) |
| Duration of smoking | ||||
| Never | 24/16 | Reference | 177/190 | Reference |
| ≤ 20 years | 11/12 | 0.6 (0.2–1.8) | 100/104 | 0.9 (0.6–1.3) |
| > 20 years | 4/12 | 0.2 (0.1–0.9) | 101/83 | 1.5 (1.0–2.1) |
| Former smokers: time since cessation of smoking | ||||
| Never | 24/16 | Reference | 177/190 | Reference |
| < 10 years | 6/3 | 1.4 (0.3–6.6) | 67/48 | 1.4 (0.9–2.2) |
| ≥ 10 years | 7/5 | 1.0 (0.3–3.8) | 56/68 | 0.9 (0.6–1.4) |
| Age started smoking | ||||
| Never | 24/16 | Reference | 177/190 | Reference |
| < 18 years | 7/9 | 0.5 (0.2–1.8) | 71/66 | 1.1 (0.7–1.6) |
| ≥ 18 years | 8/15 | 0.4 (0.1–1.1) | 130/121 | 1.2 (0.9–1.7) |
