Selected characteristics of participants at the start of postmenopausal follow-up
| Among non cases (n = 57,153) | Among cases (n = 2,155) | |
|---|---|---|
| n (%) | n (%) | |
| Y of birth | ||
| 1925–1929 | 4,623 (8.1) | 169 (7.8) |
| 1930–1934 | 7,856 (13.7) | 385 (17.9) |
| 1935–1939 | 11,616 (20.3) | 579 (26.9) |
| 1940–1944 | 14,435 (25.3) | 610 (28.3) |
| 1945–1949 | 18,623 (32.6) | 412 (19.1) |
| Family history of breast cancer in first-degree relatives | ||
| No | 50,598 (88.5) | 1,779 (82.6) |
| Yes | 6,555 (11.5) | 376 (17.4) |
| Age at menarche, y | ||
| <13 | 26,029 (45.5) | 1,011 (46.9) |
| ≥13 | 31,124 (54.5) | 1,144 (53.1) |
| Parity and age at first full-term pregnancy | ||
| Nulliparous | 6,649 (11.6) | 290 (13.5) |
| 1 or 2 children and first full-term pregnancy at age <30 | 29,278 (51.2) | 1,081 (50.2) |
| 3 or more children and first full-term pregnancy at age <30 | 16,235 (28.4) | 558 (25.9) |
| First full-term pregnancy at age ≥30 | 4,991 (8.7) | 226 (10.5) |
| BMI (kg/m2) | ||
| <18.5 | 1,871 (3.3) | 64 (3.0) |
| 18.5 to <22 | 21,033 (36.8) | 783 (36.3) |
| 22 to <25 | 20,628 (36.1) | 815 (37.8) |
| ≥25 | 13,621 (23.8) | 493 (22.9) |
| History of benign breast disease | ||
| No | 39,783 (69.6) | 1,333 (61.9) |
| Yes | 17,370 (30.4) | 822 (38.1) |
| Age at menopause, y | ||
| <49 | 14,554 (25.5) | 528 (24.5) |
| 49 to <51 | 13,722 (24.0) | 566 (26.3) |
| 51 to <53 | 16,270 (28.5) | 578 (26.8) |
| ≥53 | 12,607 (22.1) | 483 (22.4) |
| Use of menopausal hormone therapy | ||
| Never | 23,313 (40.8) | 696 (32.3) |
| Ever | 33,840 (59.2) | 1,459 (67.7) |
| Total energy intakea in 1993 (cal/d) | ||
| Quartile 1 (≤1,703) | 14,335 (25.1) | 492 (22.8) |
| Quartile 2 (1,704–2,039) | 15,062 (26.4) | 569 (26.4) |
| Quartile 3 (2,040–2,410) | 13,495 (23.6) | 528 (24.5) |
| Quartile 4 (≥2,411) | 14,261 (25.0) | 566 (26.3) |
| Alcohol intake in 1993 (g/d) | ||
| Quartile 1 (≤1.4) | 14,361 (25.1) | 488 (22.6) |
| Quartile 2 (1.5–6.1) | 14,760 (25.8) | 521 (24.2) |
| Quartile 3 (6.2–15.2) | 13,797 (24.1) | 553 (25.7) |
| Quartile 4 (≥15.3) | 14,235 (24.9) | 593 (27.5) |
| Weight gain during the previous follow-up cycle (kg/y) | ||
| ≤1 | 39,372 (68.9) | 1,504 (69.8) |
| >1 | 12,234 (21.4) | 453 (21.0) |
| Not known | 5,547 (9.7) | 198 (9.2) |
NOTE: E3N Cohort, 1993–2005 (n = 59,308).
↵aExcluding alcohol.