Table 1.
Main characteristics of the study population
| Variables | N | Controls | Cases |
|---|---|---|---|
| N = 1624 | N = 1624 | ||
| Mean (SD) or N (%) | Mean (SD) or N (%) | ||
| Age at blood collection (years) | 3248 | 52.5 (7.9) | 52.5 (8.0) |
| Length of follow-up from blood collection (years) | 3248 | – | 8.3 (2.8) |
| Age at diagnosis (years) | 1624 | – | 60.8 (8.3) |
| ER status | 1624 | ||
| Negative | – | 313 (19.3) | |
| Positive | – | 1311 (80.7) | |
| PR status | 1624 | ||
| Negative | – | 516 (31.8) | |
| Positive | – | 1108 (68.2) | |
| HER2 status | 1624 | ||
| Negative | – | 1270 (78.2) | |
| Positive | – | 354 (21.8) | |
| Age at first menstrual period (years) | 3248 | 13.1 (1.6) | 13.0 (1.5) |
| Number of full-term pregnancies | 3248 | ||
| 0 | 215 (13.2) | 244 (15.0) | |
| 1 | 253 (15.6) | 310 (19.1) | |
| 2 | 729 (44.9) | 686 (42.2) | |
| ≥ 3 | 427 (26.3) | 384 (23.6) | |
| Age at first full-term pregnancy (years) | 2789 | 24.9 (4.3) | 25.3 (4.4) |
| Ever breastfed | 3248 | ||
| No | 194 (11.9) | 206 (12.7) | |
| Yes | 1116 (68.7) | 1080 (66.5) | |
| Never pregnant | 215 (13.2) | 244 (15.0) | |
| Missing | 99 (6.1) | 94 (5.8) | |
| Use of exogenous hormones at blood collection | 3248 | ||
| No | 1124 (69.2) | 1130 (69.6) | |
| Yes | 492 (30.3) | 494 (30.4) | |
| Missing | 8 (0.5) | 0 (0.0) | |
| Menopausal status at blood collection | 3248 | ||
| Premenopausal | 434 (26.7) | 434 (26.7) | |
| Postmenopausal | 869 (53.5) | 872 (53.7) | |
| Perimenopausal | 321 (19.8) | 318 (19.6) | |
| Fasting status at blood collection (time since last meal) | 3248 | ||
| < 3 h | 737 (45.4) | 731 (45.0) | |
| 3–6 h | 284 (17.5) | 285 (17.5) | |
| > 6 h | 580 (35.7) | 580 (35.7) | |
| Unknown | 23 (1.4) | 28 (1.7) | |
| Alcohol consumption at recruitment (g/day) | 3248 | 8.9 (12.2) | 10.2 (13.5) |
| Education level | 3248 | ||
| Primary/no schooling | 610 (37.6) | 597 (36.8) | |
| Technical/professional/secondary | 687 (42.3) | 688 (42.4) | |
| Longer education | 327 (20.1) | 339 (20.9) | |
| Height (cm) | 3248 | 161.4 (6.6) | 162.0 (6.6) |
| Weight (kg) | |||
| Age at diagnosis < 50 years old | 382 | 63.8 (11.3) | 63.0 (10.9) |
| Age at diagnosis ≥ 50 years old | 2866 | 66.7 (10.8) | 68.4 (12.2) |
| Body mass index (kg/m2) | |||
| Age at diagnosis < 50 years old | 382 | 24.2 (4.1) | 23.9 (4.2) |
| Age at diagnosis ≥ 50 years old | 2866 | 25.7 (4.1) | 26.1 (4.6) |
| Waist circumference (cm) | |||
| Age at diagnosis < 50 years old | 382 | 76.8 (9.8) | 76.4 (10.3) |
| Age at diagnosis ≥ 50 years old | 2866 | 81.0 (10.4) | 82.5 (11.3) |
| Hip circumference (cm) | |||
| Age at diagnosis < 50 years old | 382 | 99.0 (8.6) | 98.3 (8.4) |
| Age at diagnosis ≥ 50 years old | 2866 | 101.4 (8.0) | 102.7 (9.1) |
ER estrogen receptor, HER2 human epidermal growth factor receptor 2, PR progesterone receptor