Table 2.

Comparison of breast cancer cases and matched controls

CharacteristicCases (N = 177)
Controls (N = 177)
n (%)n (%)
Year of birth (median)1956 (range, 1926-1974)1956 (range, 1925-1974)
Age of first live birth (median)24 (range, 17-37)23 (range, 16-36)
    012 (7)13 (7)
    ≤24102 (58)107 (61)
    >2463 (35)57 (32)
Age at menarche (median, y)13 (range, 10-18)14 (range, 9-18)
    ≤1116 (9)9 (5)
    12-1374 (42)71 (40)
    ≥1487 (49)97 (55)
BMI (median)22 (range, 17-40)24 (range, 17-44)
Parity
    012 (7)13 (7)
    139 (22)31 (18)
    284 (47)81 (46)
    328 (16)38 (21)
    48 (5)9 (5)
    >46 (3)5 (3)
Breast-feeding (mo)*
    ≤1256 (34)50 (30)
    >12109 (66)114 (70)
OC use (y)
    <5168 (95)162 (92)
    ≥59 (5)15 (8)
HRT
    Never177 (100)163 (92)
    Ever0 (0)14 (8)
Smoking (pack-years)
    <4111 (64)114 (64)
    ≥463 (36)63 (36)
  • Abbriviations: BMI, body mass index; OC, oral contraceptive; HRT, hormone replacement therapy.

  • * Nulliparous women were excluded.

  • Missing information on smoking status from three cases.