Table 1.
Main characteristics of study population by case/control status
| Controls (n = 453) | Cases (n = 453) | |
|---|---|---|
| Mean (SD) or N (%) | Mean (SD) or N (%) | |
| Age at inclusion (years) | 38.67 (5.18) | 38.76 (5.08) |
| Age at menarche (years) | 12.52 (1.83) | 12.47 (1.67) |
| Age at first full-term pregnancy (years)a | 21.89 (5.16) | 23.91 (5.86) |
| Number of full-term pregnancies (%) | ||
| 0 | 34 (7.5) | 82 (18.1) |
| 1 | 97 (21.4) | 129 (28.5) |
| 2 | 189 (41.7) | 156 (34.4) |
| 3 or more | 133 (29.4) | 86 (19.0) |
| Total duration of breastfeeding in parous women (months) (%)a | ||
| < 8 | 109 (26.0) | 155 (41.8) |
| 8–22 | 143 (34.1) | 120 (32.3) |
| > 22 | 167 (39.9) | 96 (25.9) |
| Use of hormones at blood collection (%) | 48 (10.6) | 38 (8.4) |
| Personal history of benign breast disease (%) | 55 (12.1) | 165 (36.4) |
| Level of education | ||
| ≤ Primary school | 95 (21.0) | 58 (12.8) |
| Secondary school | 247 (54.5) | 227 (50.1) |
| > Secondary school | 111 (24.5) | 168 (37.1) |
| Never smoker (%) | 203 (44.8) | 239 (52.8) |
| Moderate physical activity (hours/day) | 3.2 (2.6) | 2.4 (2.6) |
| Body mass index (kg/m2) | 29.2 (9.7) | 26.4 (5.0) |
| < 25 kg/m2 (%) | 119 (26.3) | 199 (43.9) |
| 25–29.9 kg/m2 (%) | 175 (38.6) | 175 (38.6) |
| ≥ 30 kg/m2 (%) | 159 (35.1) | 79 (17.4) |
| Waist circumference (cm) | 94.5 (15.1) | 91.0 (12.3) |
| Hip circumference (cm) | 106.5 (12.9) | 103.5 (9.9) |
| Waist/hip ratio | 0.89 (0.10) | 0.88 (0.08) |
| Tumor characteristicsb | ||
| ER-positive (irrespective of other receptors) | 215 (72.1) | |
| PR-positive (irrespective of other receptors) | 205 (68.8) | |
| HER2-positive (irrespective of other receptors) | 50 (16.8) | |
| Triple Negative: ER-/PR-/HER2- | 64 (14.1) | |
| Biomarkers (geometric mean (geometric SD)) | ||
| IL-6 (pg/ml) | 0.69 (1.92) | 0.73 (2.29) |
| IL-8 (pg/ml) c | 7.74 (2.05) | 8.27 (2.04) |
| IL-10 (pg/ml) | 0.19 (2.27) | 0.18 (2.05) |
| TNF-α (pg/ml) | 1.86 (1.50) | 1.90 (1.56) |
| IFN-γ (pg/ml) | 4.44 (2.32) | 4.07 (2.34) |
| Leptin (ng/ml) d | 14.44 (2.48) | 11.19 (2.51) |
| Adiponectin (µg/ml) | 8.12 (4.47) | 8.52 (4.21) |
| Leptin/adiponectin ratio | 1.74 (5.72) | 1.29 (5.85) |
Abbreviations: ER Estrogen receptor, HER2 Human epidermal growth factor receptor 2, IFN-γ Interferon γ, IL-6 Interleukin 6, IL-8 Interleukin 8, IL-10 Interleukin 10, PR Progesterone receptor, SD Standard deviation, TNF-α Tumor necrosis factor α.
aIn parous women only
bAvailable on 298 (65.8%) cases
cAvailable on 314 cases and 314 controls
dAvailable on 430 cases and 430 controls