Table 1.
Selected risk factors at time of mammography by case-control status and menopausal status at the time of the mammogram (NHS/NHSII)
| Premenopausal | Postmenopausal | |||
|---|---|---|---|---|
| Cases N = 559 |
Controls N = 1727 |
Cases N = 731 |
Controls N = 1695 |
|
| Mean (SD) | ||||
| Agea | 46.2 (4.6) | 46.1 (4.3) | 60.1 (7.0) | 59.6 (7.4) |
| Current BMI (kg/m2) | 25.2 (4.8) | 25.4 (5.1) | 25.9 (4.6) | 26.1 (5.0) |
| Childhood somatotype | 2.5 (1.2) | 2.6 (1.2) | 2.2 (1.2) | 2.4 (1.3) |
| Adolescent somatotype | 2.8 (1.0) | 2.9 (1.1) | 2.5 (1.1) | 2.7 (1.2) |
| BMI at age 18 (kg/m2) | 20.8 (2.5) | 21.1 (2.7) | 20.9 (2.4) | 21.1 (2.7) |
| Weight change since 18 (lbs) | 26.7 (25.8) | 26.3 (25.7) | 29.7 (25.4) | 29.7 (26.8) |
| Age at menarche | 12.3 (1.4) | 12.4 (1.4) | 12.5 (1.4) | 12.6 (1.4) |
| Parity (among parous) | 2.4 (1.0) | 2.5 (1.0) | 3.2 (1.5) | 3.2 (1.5) |
| Age at first birth (among parous) | 26.3 (4.4) | 25.9 (4.1) | 25.6 (3.7) | 25.2 (3.5) |
| Breastfeeding (months) (among parous women who ever breastfed) |
16.3 (10.6) | 17.1 (11.1) | 12.6 (10.8) | 11.4 (9.5) |
| Birth index | 46.0 (26.4) | 46.7 (25.9) | 56.4 (37.4) | 55.8 (37.7) |
| Height (inches) | 65.1 (2.6) | 64.9 (2.5) | 64.5 (2.3) | 64.6 (2.4) |
| Alcohol use (g/day) | 4.2 (6.9) | 4.2 (6.3) | 5.0 (7.5) | 4.8 (7.8) |
| Age at menopause (y) | 47.8 (5.8) | 46.7 (6.5) | ||
| Percent density | 46.1 (18.7) | 39.7 (19.0) | 29.2 (17.6) | 24.8 (17.2) |
| Dense area (cm2) | 96.8 (57.5) | 81.3 (50.8) | 50.7 (38.4) | 47.1 (38.9) |
| Non-dense area (cm2) | 121.4 (77.0) | 134.4 (80.4) | 141.3 (90.3) | 157.5 (91.1) |
| N (percent) | ||||
| Nulliparous | 81 (14.5) | 228 (13.2) | 65 (8.9) | 139 (8.2) |
| Ever breastfed (among parous) | 361 (76.5) | 1136 (76.9) | 389 (53.6) | 940 (55.8) |
| Personal history of BBD | ||||
| Confirmed by biopsy | 154 (27.5) | 287 (16.6) | 193 (26.4) | 382 (22.5) |
| Unconfirmed/unknown | 170 (30.4) | 566 (32.8) | 190 (26.0) | 423 (25.0) |
| Family history of breast cancer | 67 (12.0) | 146 (8.5) | 132 (18.1) | 225 (13.3) |
| Hormone therapy usea | ||||
| Never | 191 (26.1) | 547 (32.3) | ||
| Current | 401 (54.9) | 789 (46.5) | ||
| Past | 139 (19.0) | 359 (21.2) | ||
Number of individuals missing data on the following variables: breastfeeding (n = 42), birth index (n = 169), alcohol use (n = 275), and age at menopause (n = 17, postmenopausal only)
BMI body mass index, BBD benign breast disease
aMatching factor (matched at blood collection)