Table 1.

Characteristics of premenopausal breast cancer cases and matched controls, New York University Women's Health Study

CharacteristicsCases (n = 377)Controls (n = 377)
Mean age (SD), y44.4 (4.8)44.3 (4.8)
Mean age at diagnosis (SD), y54.4 (6.5)
Mean age at menarche (SD), y12.5 (1.5)12.4 (1.5)
Mean age at first full-term pregnancy* (SD), y26.5 (6.0)24.8 (5.4)
Nulliparous, n (%)145 (38%)134 (36%)
Family history of breast cancer, n (%)95 (25%)77 (20%)
Ever use of oral contraceptives, n (%)193 (57%)206 (62%)
Ever smoke cigarettes, n (%)197 (55%)176 (50%)
Mean height (SD), cm163.2 (6.8)162.6 (6.8)
Mean weight (SD), kg64.2 (11.8)63.6 (12.9)
Mean BMI (SD), kg/m224.1 (4.3)24.0 (4.5)
Mean 2-OHE1 (SD), pg/mL271.1 (161.8)262.5 (154.1)
Mean 16α-OHE1 (SD), pg/mL371.0 (117.1)363.2 (108.7)
Mean 2-OHE1:16α-OHE1 ratio (SD)0.79 (0.65)0.76 (0.49)

Abbreviations: 16α-OHE1, 16α-hydroxyestrone; 2-OHE1, 2-hydroxyestrone.

  • *P < 0.05. All other, P > 0.05.

  • Percentage of those whose oral contraceptives use history is known (89% of cases and 90% of controls).

  • Percentage of those whose smoking status is known (95% of cases and 93% of controls).