Table 1.

Characteristics of breast cancer cases and population controls

Cases (N = 972), no. (%)Controls (N = 1,135), no. (%)
Age (y)
    20-3967 (7)116 (10)
    40-49238 (24)310 (27)
    50-59355 (37)387 (34)
    60-69312 (32)322 (28)
Education
    High school or less389 (40)389 (34)
    Some university or technical school332 (34)422 (37)
    University graduate248 (26)323 (28)
Ethnicity
    Northern European633 (67)791 (72)
    Mixed or other European151 (16)183 (17)
    Non-European156 (17)132 (12)
Age at menarche (y)
    ≤11216 (22)212 (19)
    12253 (26)303 (27)
    13245 (25)334 (29)
    ≥14258 (27)286 (25)
Age at first birth (y)
    <20133 (14)114 (10)
    20-24282 (29)360 (32)
    25-29243 (25)322 (28)
    ≥30163 (17)193 (17)
    Nulliparous151 (16)146 (13)
Number of births
    None151 (16)146 (13)
    1152 (16)165 (15)
    2385 (40)444 (39)
    ≥3284 (29)379 (33)
Ever breast-fed
    No503 (52)497 (44)
    Yes469 (48)638 (56)
Menopausal status
    Premenopausal338 (35)464 (41)
    Postmenopausal593 (61)613 (54)
    Unknown41 (4)58 (5)
Hormone replacement ever use
    No339 (35)387 (34)
    Yes632 (65)735 (65)
Family history of breast cancer*
    No783 (81)993 (87)
    Yes189 (19)142 (13)
BMI (at age 18)
    <20432 (45)487 (43)
    20.1-24.9469 (48)555 (50)
    25.0+58 (6)79 (7)
BMI (2 years prior to reference age)
    <2069 (7)80 (7)
    20.1-24.9401 (41)487 (43)
    25.0-29.9299 (31)335 (30)
    30.0+199 (21)225 (20)
Skin color
    Fair307 (32)401 (35)
    Light171 (18)215 (19)
    Light medium365 (38)430 (38)
    Dark medium/brown/black127 (13)89 (8)
  • * Family history defined as breast cancer in mother, sister, or daughter.