Table 1.
Baseline characteristics among breast cancer cases and controls.
| Characteristics | Cases (n = 795) | Controls (n = 795) | p-Value | ||
|---|---|---|---|---|---|
| Age, mean (SD) | 50.5 | (9.5) | 50.3 | (9.4) | 0.730 a |
| Educational level, n (%) | |||||
| No formal school education/First grade | 173 | (22) | 132 | (17) | 0.001 a |
| Second grade/Vocational training | 424 | (53) | 406 | (51) | |
| University graduate | 198 | (25) | 257 | (32) | |
| Age at menarche, mean (SD) | 12.6 | (1.5) | 12.5 | (1.5) | 0.159 b |
| Age at first birth, mean (SD) | 26.5 | (4.4) | 26.2 | (4.4) | 0.129 b |
| Number of children, n (%) | |||||
| None | 172 | (22) | 178 | (22) | 0.970 a |
| 1–2 | 479 | (60) | 479 | (60) | |
| 3–4 | 133 | (17) | 128 | (16) | |
| >4 | 11 | (1) | 10 | (1) | |
| Menopausal status, n (%) | |||||
| Premenopausal | 451 | (57) | 412 | (52) | 0.050 a |
| Postmenopausal | 344 | (43) | 383 | (48) | |
| Body mass index, Kg/m2, mean (SD) | |||||
| Premenopausal | 24.5 | (4.3) | 24.8 | (4.5) | 0.146 b |
| Postmenopausal | 27.1 | (4.9) | 26.3 | (4.1) | 0.009 b |
| Waist circumference (cm) | 88.1 | (14.2) | 87.2 | (12.8) | 0.146 b |
| Hormone replacement therapy use, n (%) | |||||
| Never | 702 | (88) | 712 | (90) | 0.386 b |
| Ever | 93 | (12) | 83 | (10) | |
| Previous benign breast problems, n (%) | |||||
| No | 620 | (78) | 651 | (82) | 0.052 a |
| Yes | 175 | (22) | 144 | (18) | |
| Family history of breast cancer, n (%) | |||||
| None | 597 | (75) | 639 | (80) | 0.033 a |
| Second degree | 101 | (13) | 85 | (11) | |
| First degree | 97 | (12) | 71 | (9) | |
| Self-assessed physical activity last year, n (%) | |||||
| Sedentary/slightly active | 297 | (37) | 266 | (33) | 0.332 b |
| Moderately active | 281 | (35) | 313 | (39) | |
| Active/very active | 217 | (27) | 217 | (27) | |
| Alcohol consumption (g/day), n (%) | |||||
| No | 190 | (24) | 184 | (23) | 0.537 b |
| <10 | 440 | (55) | 469 | (59) | |
| ≥10 | 164 | (21) | 142 | (18) | |
| Smoking, n (%) | |||||
| Never smoker | 343 | (43) | 332 | (42) | 0.367 b |
| Former smoker ≥ 6 months ago | 208 | (26) | 203 | (26) | |
| Smoker or former smoker < 6 months | 244 | (31) | 260 | (33) | |
| Caloric intake (Kcal/day), mean (SD) | 1991.1 | (623.4) | 1903.8 | (659.9) | 0.005 b |
| Tumor subtype c, n (%) | |||||
| HR+ | 532 | (67) | |||
| HER2+ | 162 | (20) | |||
| TN | 99 | (12) | |||
Abbreviations: HR+ = hormone receptor positive tumors (ER+ and/or PR+, with HER2-); HER2+ = human epidermal growth factor receptor 2 positive tumors; TN = triple negative tumors. a p-value resulting from Pearson Chi-Square test (completed variables). b p-value resulting from conditional logistic regression models (imputed variables). c Two breast cancer cases could not be classified.