Table 4.
Full models for breast cancer incidence with a 10-year lag, restricted subcohorta by race.
| Variable | Hazard ratio (95% CI) |
|---|---|
| White women (131 cases) | |
| Model 1: Continuous cumulative exposure (per 1,000 unit-years) | 1.00 (1.00–1.00) |
| Born < 1920 (reference group) | 1.00 |
| Born 1920–1934 | 3.07 (1.63–5.78) |
| Born ≥ 1935 | 7.81 (3.65–16.7) |
| Self-respondent | 0.31 (0.19–0.50) |
| Parous | 0.30 (0.10–0.84) |
| Age at first live birth | 1.07 (1.03–1.11) |
| Positive family history | 1.60 (1.05–2.44) |
| Model 2: Years exposedb | 1.02 (0.99–1.05) |
| Model 3: Categorical cumulative exposure (per 1,000 unit-years)b | |
| 0 to < 0.16 (n = 32) | 1.00 |
| 0.16 to < 0.46 (n = 33) | 1.36 (0.83–2.23) |
| 0.46 to < 1.6 (n = 34) | 1.15 (0.70–1.89) |
| ≥ 1.6 (n = 32) | 1.27 (0.75–2.17) |
| Nonwhite women (14 cases) | |
| Model 4: Continuous cumulative exposure (per 1,000 unit-years) | 1.33 (1.14–1.56) |
| Born < 1920 (reference group) | 1.00 |
| Born 1920–1934 | 0.94 (0.22–4.07) |
| Born ≥ 1935 | 3.75 (0.51–27.8) |
| Self-respondent | 0.07 (0.02–0.26) |
| Ever-smoker | 3.84 (1.01–14.6) |
| Model 5: Years exposedc | 1.13 (1.03–1.23) |
| Model 6: Categorical cumulative exposure (per 1,000 unit-years)c | |
| < 0.47 (n = 4) | 1.00 |
| 0.47 to < 3.9 (n = 3) | 0.60 (0.12–3.01) |
| 3.9 to < 5.8 (n = 4) | 7.65 (1.11–52.8) |
| ≥ 5.8 (n = 3) | 22.3 (2.38–209) |
a
Restricted cohort comprises women with questionnaire data for ever smoking, parity, age at first live birth, breast cancer in first-degree female relative, hormone use, and age began hormone use.
b
Models control for birth cohort (1920–1934, ≥ 1935, vs. < 1920); self-respondent, parity, age at first live birth, and positive family history).
c
Models control for birth cohort (1920–1934, ≥ 1935, vs. <1920); self-respondent and ever-smoker).