Table 1.
Characteristics of the breast cancer metabolomics case–control study participants.
| Baseline characteristic | Mean ± SD or frequency (%) | ||
|---|---|---|---|
| Controls (N = 791) | Cases (N = 791) | P-valuea | |
| Age at blood collection (years) | 56.8 ± 6.6 | 56.8 ± 6.6 | – |
| Menopausal status at blood collection | |||
| Pre-menopausal | 180 (22.5) | 179 (22.5) | – |
| Post-menopausal | 611 (77.5) | 612 (77.5) | |
| Fasting status at blood collection | |||
| Fasting | 287 (36.3) | 287 (36.3) | – |
| Non-fasting | 504 (63.7) | 504 (63.7) | |
| Follow-up time to cancer diagnosis | |||
| 5 years or less | – | 412 (52.1) | – |
| More than 5 years | – | 379 (47.9) | |
| BMI (kg/m2) | |||
| Underweight or normal (<25) | 538 (68.3) | 564 (71.4) | 0.27 |
| Overweight25–30 | 204 (25.9) | 177 (22.4) | |
| Obese (≥30) | 46 (5.8) | 49 (6.2) | |
| Unknown | 3 (0.4) | 1 (0.1) | |
| Waist to hip ratio | |||
| <0.8 | 589 (74.8) | 573 (72.6) | 0.33 |
| ≥0.8 | 198 (25.2) | 216 (27.4) | |
| Unknown | 4 (0.5) | 2 (0.3) | |
| Smoking status | |||
| Yes | 66 (8.3) | 62 (7.8) | 0.78 |
| No | 725 (91.7) | 724 (92.2) | |
| Diabetic status | |||
| Yes | 32 (4.0) | 27 (3.4) | 0.6 |
| No | 759 (96.0) | 764 (96.6) | |
| Reported alcohol intake, g/day | 11.7 ± 15.0 | 12.6 ± 15.4 | 0.25 |
| Lifetime alcohol drinking pattern | |||
| Non-consumers (0 g/day) | 153 (19.5) | 146 (18.5) | 0.48 |
| Light consumers (1–10 g/day) | 334 (42.5) | 321 (40.6) | |
| Drinkers (>10 g/day) | 298 (38.0) | 323 (40.9) | |
| Unknown | 6 (0.8) | 1 (0.1) | |
| Blood pressure status | |||
| Normal | 642 (81.8) | 653 (83.0) | 0.55 |
| Hypertensive | 143 (18.2) | 133 (17.0) | |
| Unknown | 6 (0.8) | 5 (0.6) | |
| Previous use of oral contraceptives | |||
| Yes | 768 (97.7) | 769 (97.8) | 1 |
| No | 18 (2.3) | 17 (2.1) | |
| Previous breastfeeding | |||
| Yes | 493 (63.9) | 472 (61.1) | 0.26 |
| No | 27836 | 301 (39.0) | |
| Unknown | 6 (0.8) | 5 (0.6) | |
| Menopause hormone therapy use at blood collection (post-menopausal) | |||
| Yes | 371 (46.9) | 416 (52.6) | 0.01 |
| No | 240 (30.3) | 304 (24.8) | |
| Duration of use of menopause hormonal treatment, years (post-menopausal) | 3.9 ± 4.5 | 4.4 ± 4.7 | 0.06 |
aNon-matching factors tested using a Chi-square test or Wilcoxon signed rank test.