Table 1.
Selected characteristics of study participants.
|
Cases (n = 1037) Mean (SD)/N(%) |
Controls (n = 1050) Mean (SD)/N(%) |
|
| Age | 57.0 (10.3) | 56.5 (10.1) |
| Body mass index (kg/m2) | 25.6 (5.4) | 25.0 (4.7) |
| Ethnicity | ||
| European | 641 (61.8%) | 806 (76.8%) |
| East Asian | 305 (29.4%) | 168 (16.0%) |
| South Asian | 31 (3.0%) | 31 (2.9%) |
| Mixed/other | 60 (5.8%) | 45 (4.3%) |
| Household income | ||
| <$30,000 | 181 (17.5%) | 104 (9.9%) |
| $30,000–$59,999 | 255 (24.6%) | 230 (21.9%) |
| $60,000–$99,999 | 229 (22.1%) | 262 (25.0%) |
| >$100,000 | 221 (21.3%) | 310 (29.5%) |
| Not stated | 151 (14.6%) | 144 (13.7%) |
| Education | ||
| High school or less | 353 (34.3%) | 259 (24.7%) |
| College/trade certificate | 312 (30.3%) | 310 (29.6%) |
| Undergraduate degree | 244 (23.7%) | 271 (25.9%) |
| Graduate/professional degree | 121 (11.7%) | 207 (19.8%) |
| Menopausal status | ||
| Premenopausal | 351 (33.9%) | 391 (37.2%) |
| Postmenopausal | 684 (66.1%) | 659 (62.8%) |
| Reproductive history | ||
| Age at menarche (years) | 12.9 (1.6) | 12.8 (1.5) |
| Ever been pregnant | 856 (82.8%) | 825 (78.7%) |
| Age at first birth (years) | 27.8 (5.4) | 27.7 (5.3) |
| Number of pregnancies | 2.3 (1.7) | 2.2 (1.7) |
| Age at first mammogram (years) | 44.5 (8.6) | 42.7 (7.4) |
| Family history of breast cancer | 204 (19.7%) | 145 (13.8%) |
| Current smoker | 66 (6.4%) | 62 (5.9%) |
| Pack-years smoking | 5.7 (12.3) | 5.1 (10.9) |
| Lifetime alcohol consumption (#drinks/week) | ||
| Teen | 1.1 (3.7) | 1.6 (4.0) |
| 20s | 2.6 (5.5) | 3.9 (8.1) |
| 30s | 2.9 (6.1) | 3.5 (5.4) |
| 40s | 3.2 (6.1) | 3.7 (5.6) |
| 50s | 2.8 (4.9) | 3.8 (6.2) |
| Last 2 years | 2.1 (4.5) | 2.9 (5.0) |
| Moderate-to-vigorous physical activity (MET-hours/week) | ||
| Leisure time | 14.5 (19.0) | 23.0 (32.3) |
| Household | 39.7 (58.5) | 48.9 (83.1) |
| Occupational | 54.4 (76.8) | 45.4 (66.4) |
| Medication use | ||
| Oral contraceptive | 570 (55.0%) | 695 (66.2%) |
| Hormone replacement therapy | 327 (31.7%) | 351 (33.5%) |