Table 3.
Risk of breast cancer associated with HRT: Ever- use vs. never use of HRT.
| e-case1 | e-ctrl.1 | Crude OR (95% CI) | Adj. OR (95% CI) | |
| Ever HRT | 1492 | 3142 | 1.1 (0.99–1.2) | 1.2 (1.0–1.3) |
| Duration of use2 | ||||
| <2 yrs | 387 | 770 | 1.3 (1.1–1.5) | 1.3 (1.1–1.6) |
| 2–4 yrs | 223 | 670 | 0.8 (0.7–0.9) | 0.9 (0.7–1.1) |
| 5–7 yrs | 278 | 609 | 1.0 (0.9–1.2) | 1.1 (0.9–1.3) |
| 8+ yrs | 604 | 1093 | 1.2 (1.0–1.4) | 1.2 (1.1–1.4) |
| Time since first use2 | P trend = .08 | P trend = .06 | ||
| 1–4 yrs | 514 | 1187 | 1.1 (0.97–1.3) | 1.2 (1.1–1.4) |
| 5–9 yrs | 556 | 1098 | 1.1 (0.98–1.3) | 1.2 (1.0–1.4) |
| 10–14 yrs | 294 | 599 | 1.0 (0.9–1.2) | 0.97 (0.8–1.2) |
| 15+ yrs | 128 | 258 | 1.1 (0.9–1.4) | 0.96 (0.7–1.3) |
| Time since last use2 | P trend = .19 | P trend = .51 | ||
| -1 yr/current use | 1381 | 2908 | 1.1 (0.99–1.2) | 1.2 (1.0–1.3) |
| 1–2 yrs | 71 | 162 | 0.96 (0.7–1.3) | 0.9 (0.6–1.3) |
| 3–4 yrs | 31 | 63 | 1.0 (0.6–1.6) | 1.1 (0.6–1.9) |
| 5+ yrs | 9 | 9 | 1.7 (0.6–4.3) | 2.3 (0.7–7.2) |
| P trend = .14 | P trend = .054 |
Conditional logistic regression analysis [Odds ratios (OR) and 95% confidence intervals]; adjustment for BMI, family history of breast cancer, childbearing history, age at first live birth, duration of breast-feeding, age at menarche, ever OC use, education. Index dates 0.5 = exposure information was not considered 0.5 year prior to cancer diagnosis.
1 e-case, e-ctrl = number of observations for exposed case or exposed control respectively.
2 time variables were rounded