Table 2.
Risks of breast-cancer-specific and overall survival according to age at first pregnancy stratified by menopausal status
| Premenopausal | Postmenopausal | |||||
|---|---|---|---|---|---|---|
| Case | Events | HR (95% CI) | Case | Events | HR (95% CI) | |
| AFP | Breast cancer specific survival | |||||
| Nulliparous | 4441 | 269 | Ref | 502 | 17 | Ref |
| <20 | 202 | 5 | 0.436 (0.180-1.057) | 318 | 18 | 1.492 (0.769-2.896) |
| 20-24 | 3756 | 100 | 0.429 (0.341-0.540) | 2897 | 116 | 1.090 (0.655-1.813) |
| 25-29 | 8114 | 193 | 0.376 (0.312-0.452) | 2809 | 88 | 0.834 (0.496-1.403) |
| ≥30 | 2178 | 51 | 0.372 (0.275-0.501) | 693 | 38 | 1.508 (0.851-2.673) |
| p-value | <.0001 | 0.0172 | ||||
| AFP | Overall survival | |||||
| Nulliparous | 4441 | 561 | Ref | 502 | 47 | Ref |
| <20 | 202 | 16 | 0.672 (0.409-1.105) | 318 | 49 | 1.404 (0.941-2.095) |
| 20-24 | 3756 | 274 | 0.551 (0.477-0.637) | 2897 | 332 | 1.076 (0.793-1.460) |
| 25-29 | 8114 | 513 | 0.468 (0.415-0.528) | 2809 | 231 | 0.748 (0.546-1.023) |
| ≥30 | 2178 | 159 | 0.547 (0.459-0.653) | 693 | 87 | 1.183 (0.830-1.687) |
| p-value | <.0001 | <.0001 | ||||