Characteristics and hormone levels of subjects (cases and subcohort) at baseline
| Breast cancer cases* | Subcohort | ||
|---|---|---|---|
| n = 197 | n = 857 | ||
| Age, y; mean, SD (range) | 62, 5 (48-70) | 61, 6 (46-70) | |
| Country of birth, n (%) | Australia/New Zealand | 144 (73.1) | 569 (66.4) |
| United Kingdom | 9 (4.6) | 47 (5.5) | |
| Italy | 26 (13.2) | 134 (15.6) | |
| Greece | 18 (9.1) | 107 (12.5) | |
| Age at menarche, n (%) | Less than 12 y | 27 (13.7) | 109 (12.7) |
| 12 y | 35 (17.8) | 160 (18.7) | |
| 13 y | 56 (28.4) | 217 (25.3) | |
| 14 y or more | 79 (40.1) | 371 (43.3) | |
| Parity and age at first pregnancy (live birth or gestation >24 wk), n (%) | Nulliparous | 30 (15.2) | 100 (11.7) |
| 1 and <25 | 5 (2.5) | 15 (1.8) | |
| >1 and <25 | 75 (38.1) | 358 (41.8) | |
| 1 and ≥25 | 11 (5.6) | 52 (6.1) | |
| >1 and ≥25 | 76 (38.6) | 332 (38.7) | |
| Lactation, n (%) | Never | 63 (32.0) | 214 (25.0) |
| Up to 6 mo | 35 (17.8) | 184 (21.5) | |
| 7-12 mo | 32 (16.2) | 147 (17.2) | |
| 13-24 mo | 43 (21.8) | 173 (20.2) | |
| >24 mo | 24 (12.2) | 139 (16.2) | |
| Oral contraceptive use, n (%) | Never user | 123 (62.4) | 492 (57.4) |
| Past user | 74 (37.6) | 365 (42.6) | |
| HRT use, n(%) | Never user | 174 (88.3) | 760 (88.7) |
| Past user | 23 (11.7) | 97 (11.3) | |
| Physical activity, n (%) | None | 38 (19.3) | 182 (21.2) |
| Low | 45 (22.8) | 176 (20.5) | |
| Medium | 78 (39.6) | 341 (39.8) | |
| High | 36 (18.3) | 158 (18.4) | |
| Alcohol, n (%) | Abstainers | 89 (45.2) | 403 (47.0) |
| Exdrinkers | 6 (3.0) | 31 (3.6) | |
| 1-19 g/d | 82 (41.6) | 339 (39.6) | |
| 20-39 g/d | 14 (7.1) | 69 (8.1) | |
| 40 g/d or more | 6 (3.0) | 15 (1.8) | |
| Smoking, n (%) | Never | 150 (76.1) | 612 (71.4) |
| Current | 11 (5.6) | 74 (8.6) | |
| Past | 36 (18.3) | 171 (20.0) | |
| Education, n (%) | Primary school | 46 (23.4) | 247 (28.8) |
| Some high school | 98 (49.7) | 378 (44.1) | |
| Completed high school | 33 (16.8) | 130 (15.2) | |
| Degree/diploma | 20 (10.2) | 102 (11.9) | |
| BMI (kg/m2); mean, SD | 27.7, 4.7 | 27.3, 4.7 | |
| Energy from diet (MJ/d); mean, SD | 8.3, 2.7 | 8.5, 2.9 | |
| Hormones and SHBG, median (interquartile range)† | |||
| Total estradiol (pmol/L) | 57.00 (46.00-74.00) | 57.00 (45.35-71.00) | |
| Free estradiol (pmol/L) | 0.87 (0.63-1.13) | 0.80 (0.60-1.05) | |
| Estrone sulfate (nmol/L) | 3.22 (2.29-4.41) | 2.95 (2.15-4.03) | |
| Testosterone (nmol/L) | 0.70 (0.50-1.10) | 0.70 (0.50-1.10) | |
| DHEAS (μmol/L) | 1.50 (1.00-2.30) | 1.50 (0.90-2.40) | |
| Androstenedione (nmol/L) | 2.19 (1.60-3.17) | 2.16 (1.41-3.06) | |
| SHBG (nmol/L) | 43.10 (32.90-57.30) | 51.10 (38.55-67.80) | |
↵*Nineteen breast cancer cases were also in the subcohort.
↵†The number of missing measures among cases and in the subcohort were as follows: 2 and 15 for total estradiol, 2 and 16 for free estradiol, 5 and 16 for estrone sulfate, 1 and 4 for testosterone, 0 and 3 for DHEAS, 1 and 3 for androstenedione, 0 and 1 for SHBG.