Table 1.

Distribution of demographic and reproductive characteristics of 969 case patients with ERPR-positive and ERPR-negative breast cancer and control subjects ages 55 to 64 years in the Women's CARE Study

CharacteristicsCases, n (%)
Controls, n (%)
ERPR-positiveERPR-negativen (%)P*
708 (73.1)261 (26.9)1,455
Reference age (y)
    55-59349 (49.3)148 (56.7)772 (53.1)
    60-64359 (50.7)113 (43.3)683 (46.9)0.09
Race
    White542 (76.6)143 (54.8)961 (66.1)
    African American166 (23.5)118 (45.2)494 (34.0)0.0001
Parity status
    Nulligravid72 (10.2)11 (4.2)107 (7.4)
    At least one full-term pregnancy636 (89.8)250 (95.8)1348 (92.7)0.005
No. full-term pregnancies
    186 (13.5)25 (10.0)147 (10.9)
    2215 (33.8)69 (27.6)350 (26.0)
    3157 (24.7)68 (27.2)345 (25.6)
    ≥4178 (28.0)88 (35.2)506 (37.5)0.0004
Age at first full-term pregnancy (y)
    ≤19165 (25.9)93 (37.2)454 (33.7)
    20-24278 (43.7)104 (41.6)622 (46.1)
    25-29142 (22.3)37 (14.8)190 (14.1)
    ≥3051 (8.02)16 (6.4)82 (6.1)0.0001
Ever breastfed
    No291 (45.8)113 (45.2)555 (41.2)
    Yes345 (54.3)137 (54.8)793 (58.8)0.12
  • * χ2 test for differences in the distribution of characteristics by case/control status.

  • Women with a history of short-term pregnancies <26 wk but no full-term pregnancies excluded (20 ERPR-positive cases, 6 ERPR-negative cases, and 43 controls).