Table 1.
Distributions of selected characteristics in breast cancer cases and cancer-free controls
| Characteristics | Cases (n=1,005), n (%) |
Controls (n=1,020), n (%) |
P-value |
|---|---|---|---|
| Age at diagnosis, years (mean ± SD) | 46.5±10.2 | 46.7±11.1 | 0.646 |
| Body mass index, kg/m2 (mean ± SD) | 23±3.2 | 22.5±2.6 | <0.001 |
| Age at menarche, years (mean ± SD) | 15.5±1.7 | 15.2±1.6 | 0.001 |
| Age at menopause, years (mean ± SD) | 49.8±3.6 | 49.9±3.5 | 0.598 |
| Age at first live birth, years (mean ± SD) | 25±3.5 | 24.2±3.4 | <0.001 |
| Menopausal status | 0.059 | ||
| Premenopausal | 656 (65.3) | 668 (65.5) | |
| Postmenopausal | 342 (34) | 333 (32.6) | |
| Unnatural menopausea | 7 (0.7) | 19 (1.9) | |
| Pregnancies, n | <0.001 | ||
| ≤2 | 570 (56.7) | 404 (39.6) | |
| >2 | 435 (43.3) | 616 (60.4) | |
| Hormone therapy | 0.013 | ||
| Yes | 45 (4.5) | 25 (2.5) | |
| No | 960 (95.5) | 995 (97.5) | |
| Previous benign breast disease | 0.054 | ||
| Yes | 41 (4.1) | 26 (2.5) | |
| No | 964 (95.9) | 994 (97.5) | |
| Family history of breast cancer | <0.001 | ||
| Yes | 75 (7.5) | 12 (1.2) | |
| No | 930 (92.5) | 1,008 (98.8) | |
| ER status | |||
| Positive | 678 (67.5) | ||
| Negative | 327 (32.5) | ||
| PR status | |||
| Positive | 618 (61.5) | ||
| Negative | 387 (38.5) | ||
| HER2 status | |||
| Positive | 275 (27.4) | ||
| Negative | 730 (72.6) |
Note:
a
Included hysterectomy operation and other status.
Abbreviations: ER, estrogen receptor; HER2, human epidermal growth factor receptor 2; PR, progesterone receptor.