Table 5.
Odds ratios (ORs) for breast cancer and smoking in relation to the CYP1A1 genotype at the M2 locus (white women only)
| M2 genotypesa | wt genotypeb | |||
| Cases/controls | OR (95% CI)c | Cases/controls | OR (95% CI)c | |
| Active smoking status | ||||
| Never | 15/15 | Referent | 186/191 | Referent |
| Former | 11/18 | 0.5 (0.2–1.6) | 125/106 | 1.2 (0.9–1.7) |
| Current | 6/6 | 0.9 (0.2–3.5) | 74/81 | 0.9 (0.6–1.4) |
| Number of cigarettes (pack/day) | ||||
| Never | 15/15 | Referent | 186/191 | Referent |
| ≤ 1 | 10/11 | 0.8 (0.3–2.6) | 126/114 | 1.1 (0.8–1.6) |
| > 1 | 7/13 | 0.5 (0.1–1.5) | 71/72 | 1.0 (0.7–1.5) |
| Duration of smoking | ||||
| Never | 15/15 | Referent | 186/191 | Referent |
| ≤ 20 years | 6/16 | 0.3 (0.1–1.0) | 105/100 | 1.0 (0.7–1.4) |
| > 20 years | 11/8 | 1.4 (0.4–4.8) | 94/87 | 1.3 (0.9–1.8) |
| Former smokers: time since cessation of smoking | ||||
| Never | 15/15 | Referent | 186/191 | Referent |
| < 10 years | 10/7 | 1.3 (0.4–4.3) | 63/44 | 1.4 (0.9–2.2) |
| ≥ 10 years | 1/11 | 0.1 (0.0–0.8) | 62/62 | 1.1 (0.7–1.7) |
| Age started smoking | ||||
| Never | 15/15 | Referent | 186/191 | Referent |
| < 18 years | 6/8 | 0.5 (0.1–2.0) | 72/67 | 1.0 (0.7–1.6) |
| ≥ 18 years | 11/16 | 0.7 (0.2–2.0) | 127/120 | 1.1 (0.8–1.6) |
CI, confidence interval; wt, wild type. a M2/M2 and M2/wt genotypes. b wt/wt genotype. cAdjusted for age and sampling fractions.