Table 1.
Participant characteristics in the NHS according to average body size during ages 10-20 years
| Participant characteristics | Overall (N = 835) | Shape 1 (n = 91) | Shape 1.5-2 (n = 261) | Shape 2.5-3 (n = 259) | Shape 3.5-4 (n = 164) | Shape ≥4.5 (n = 60) |
|---|---|---|---|---|---|---|
| NHS cohort, No. (%) | ||||||
| NHSI | 501 (60.0) | 72 (79.1) | 164 (62.8) | 145 (56.0) | 84 (51.2) | 36 (60.0) |
| NHSII | 334 (40.0) | 19 (20.9) | 97 (37.2) | 114 (44.0) | 80 (48.8) | 24 (40.0) |
| Age at diagnosis, mean (SD), y | 59.1 (11.3) | 64.1 (10.7) | 59.0 (11.4) | 58.4 (11.1) | 57.4 (11.1) | 59.4 (11.3) |
| Age at menarche, mean (SD), y | 12.4 (1.4) | 12.9 (1.3) | 12.5 (1.3) | 12.4 (1.4) | 12.2 (1.5) | 12.1 (1.3) |
| Median year of diagnosis | 1999 | 2000 | 1999 | 2000 | 2000 | 2000 |
| ER, No. (%) | ||||||
| Positive | 673 (80.6) | 73 (80.2) | 204 (78.2) | 205 (79.2) | 140 (85.4) | 51 (85.0) |
| Negative | 162 (19.4) | 18 (19.8) | 57 (21.8) | 54 (20.8) | 24 (14.6) | 9 (15.0) |
| Race, No. (%) | ||||||
| White | 797 (95.4) | 87 (95.6) | 247 (94.6) | 244 (94.2) | 161 (98.2) | 58 (96.7) |
| Others | 38 (4.6) | 4 (4.4) | 14 (5.4) | 15 (5.8) | 3 (1.8) | 2 (3.3) |
| Family history of breast cancer, No. (%) | ||||||
| No | 679 (83.1) | 78 (85.7) | 219 (83.9) | 217 (83.8) | 129 (78.7) | 54 (90.0) |
| Yes | 138 (16.9) | 13 (14.3) | 42 (16.1) | 42 (16.2) | 35 (21.3) | 6 (10.0) |
| Menopausal statusa, No. (%) | ||||||
| Premenopausal | 229 (27.4) | 14 (15.4) | 67 (25.7) | 75 (29.0) | 56 (34.1) | 17 (28.3) |
| Postmenopausal | 571 (68.4) | 75 (82.4) | 179 (68.6) | 175 (67.5) | 100 (61.0) | 42 (70.0) |
| Unknown | 35 (4.2) | 2 (2.2) | 15 (5.7) | 9 (3.5) | 8 (4.9) | 1 (1.7) |
| Recent BMIa, mean (SD), kg/m2 | 26.1 (5.1) | 24.6 (4.0) | 24.8 (4.1) | 26.1 (4.8) | 27.8 (6.1) | 28.8 (6.4) |
| Cumulative average physical activity, mean (SD), MET-h/wk | 18.6 (17.3) | 18.9 (15.0) | 19.3 (17.7) | 17.4 (14.4) | 19.2 (21.3) | 18.3 (19.0) |
| Cumulative average alcohol consumption, mean (SD), g/d | 5.8 (8.8) | 5.8 (8.6) | 5.6 (8.2) | 5.8 (9.2) | 6.6 (9.3) | 5.2 (8.5) |
a
Defined as 1 cycle before breast cancer diagnosis. BMI = body mass index; ER = estrogen receptor; MET = metabolic equivalents; NHS = Nurses’ Health Study; NHSI = Nurses’ Health Study cohort I; NHSII = Nurses’ Health Study cohort II.