Table 1.

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
 1925–19294,623 (8.1)169 (7.8)
 1930–19347,856 (13.7)385 (17.9)
 1935–193911,616 (20.3)579 (26.9)
 1940–194414,435 (25.3)610 (28.3)
 1945–194918,623 (32.6)412 (19.1)
Family history of breast cancer in first-degree relatives
 No50,598 (88.5)1,779 (82.6)
 Yes6,555 (11.5)376 (17.4)
Age at menarche, y
 <1326,029 (45.5)1,011 (46.9)
 ≥1331,124 (54.5)1,144 (53.1)
Parity and age at first full-term pregnancy
 Nulliparous6,649 (11.6)290 (13.5)
 1 or 2 children and first full-term pregnancy at age <3029,278 (51.2)1,081 (50.2)
 3 or more children and first full-term pregnancy at age <3016,235 (28.4)558 (25.9)
 First full-term pregnancy at age ≥304,991 (8.7)226 (10.5)
BMI (kg/m2)
 <18.51,871 (3.3)64 (3.0)
 18.5 to <2221,033 (36.8)783 (36.3)
 22 to <2520,628 (36.1)815 (37.8)
 ≥2513,621 (23.8)493 (22.9)
History of benign breast disease
 No39,783 (69.6)1,333 (61.9)
 Yes17,370 (30.4)822 (38.1)
Age at menopause, y
 <4914,554 (25.5)528 (24.5)
 49 to <5113,722 (24.0)566 (26.3)
 51 to <5316,270 (28.5)578 (26.8)
 ≥5312,607 (22.1)483 (22.4)
Use of menopausal hormone therapy
 Never23,313 (40.8)696 (32.3)
 Ever33,840 (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)
 ≤139,372 (68.9)1,504 (69.8)
 >112,234 (21.4)453 (21.0)
 Not known5,547 (9.7)198 (9.2)

NOTE: E3N Cohort, 1993–2005 (n = 59,308).

  • aExcluding alcohol.