Table 1.

Distribution of person-years according to hormone therapy formulation and selected endometrial carcinoma risk factors

No hormone therapy (%)Unopposed estrogens (%)Estrogen plus progestin (%)Estrogen, unknown progestin (%)Total person-years*RR (95% CI)
Attained age (y)
    <557312537,4491.0 (Reference)
    55-59651212442,4021.2 (0.4-3.3)
    60-64551519585,3921.6 (0.6-4.3)
    65-69501919790,5222.7 (0.98-7.3)
    70-74482216973,0813.2 (1.2-8.7)
    75-794824121148,6333.3 (1.2-9.2)
    ≥80532271249,6963.0 (1.1-8.0)
Race/ethnicity
    White5021176295,5981.0 (Reference)
    Non-White6013913101,5770.8 (0.7-0.99)
Formal education
    Less than high school581871050,4921.0 (Reference)
    High school graduate5519137162,5651.2 (0.9-1.5)
    Beyond high school4918207184,1181.3 (0.99-1.7)
Household income in 1973
    <$10,00059187980,3241.0 (Reference)
    $10,000-29,9995219167247,9401.4 (1.1-1.8)
    ≥$30,000451924750,7721.8 (1.3-2.4)
    Unknown561910818,1390.6 (0.4-1.2)
Age at menarche (y)
    ≤11531716761,0831.0 (Reference)
    12-135219167220,8601.0 (0.8-1.3)
    ≥145419138115,2320.7 (0.6-0.97)
Age at menopause (y)
    ≤48522212994,6301.0 (Reference)
    49-515418157169,0260.9 (0.7-1.1)
    ≥525217187133,5181.1 (0.8-1.3)
Oral contraceptive use (y)
    None5620127293,5671.0 (Reference)
    ≤2441625746,0361.1 (0.9-1.5)
    >2441326856,6010.7 (0.5-0.9)
    Unknown301615199710.7 (0.1-5.2)
Parity
    0532113860,2471.0 (Reference)
    1 or 25220158164,3130.9 (0.7-1.1)
    ≥35417167172,6150.6 (0.5-0.8)
BMI (kg/m2)
    <18.5471819108,8470.8 (0.4-1.6)
    18.5-24.94919188253,8011.0 (Reference)
    25-29.9581811891,7571.0 (0.8-1.2)
    30-34.963157724,3551.5 (1.1-2.1)
    ≥356814658,8662.5 (0.7-3.7)
    Unknown59141469,5490.8 (0.4-1.5)
Smoking status
    Never5320165207,4981.0 (Reference)
    Current532411649,3350.7 (0.5-0.97)
    Former461922699,1161.1 (0.9-1.3)
    Unknown68312541,2261.1 (0.8-1.4)
BCDDP participant type
    Surgery for benign breast disease5319158158,1331.0 (Reference)
    No breast disease or surgery5218158172,7141.0 (0.8-1.2)
    Recommended for surgery541815766,3281.0 (0.8-1.3)
  • NOTE: RRs adjusted for attained age and calendar time.

  • * Percentages do not sum to 100 because some hormone therapy formulations are not included: progestins only or progestins with unknown estrogen use (3,404 person-years) and unknown hormone therapy use (21,256 person-years).