Table 2.

Endogenous factors and risk for breast cancer defined by joint ER and PR status

Control group
ERPR
ER+PR
ERPR+
ER+PR+
Unknown ERPR
P, Wald (df)*
nnOR (95% CI)nOR (95% CI)nOR (95% CI)nOR (95% CI)nOR (95% CI)
Parous
    No348421.0 (Ref)471.0 (Ref)61.0 (Ref)1731.0 (Ref)1401.0 (Ref)0.31 (1)
    Yes2,7172900.8 (0.6-1.2)2390.7 (0.5-0.9)651.4 (0.6-3.2)9920.7 (0.6-0.9)6490.6 (0.5-0.7)
Age at first birth (y)§
    <20311240.7 (0.4-1.1)130.5 (0.3-1.0)81.0 (0.5-2.3)930.9 (0.7-1.2)691.1 (0.8-1.5)
    20-241,1641291.0 (Ref)981.0 (Ref)291.0 (Ref)3691.0 (Ref)2391.0 (Ref)0.059 (3)
    25-29858830.8 (0.6-1.1)801.0 (0.8-1.4)200.9 (0.5-1.6)3401.2 (1.0-1.4)2181.2 (0.9-1.4)
    ≥30384541.1 (0.8-1.6)481.2 (0.8-1.8)81.0 (0.4-2.2)1901.5 (1.2-1.8)1231.4 (1.1-1.8)
No. births
    1573811.0 (Ref)701.0 (Ref)91.0 (Ref)2471.0 (Ref)1611.0 (Ref)0.37 (3)
    21,0991290.8 (0.6-1.1)980.8 (0.6-1.1)301.6 (0.8-3.6)4350.9 (0.8-1.1)3021.0 (0.8-1.3)
    3653560.6 (0.4-0.9)550.8 (0.5-1.1)211.9 (0.8-4.4)*2130.8 (0.7-1.0)1250.7 (0.5-0.9)
    ≥4392240.5 (0.3-0.8)160.4 (0.2-0.7)50.8 (0.3-2.5)970.7 (0.5-0.9)610.6 (0.4-0.9)
Age at menarche (y)
    <12166271.5 (1.0-2.4)140.9 (0.5-1.7)102.3 (1.1-5.0)831.2 (0.9-1.7)521.2 (0.8-1.7)
    12-131,1871201.0 (Ref)1131.0 (Ref)281.0 (Ref)4541.0 (Ref)3051.0 (Ref)0.56 (3)
    14-151,2001291.1 (0.9-1.5)1231.1 (0.8-1.4)240.9 (0.5-1.6)4291.0 (0.9-1.2)3151.1 (0.9-1.3)
    ≥16241231.0 (0.6-1.7)150.6 (0.4-1.1)40.8 (0.3-2.3)800.9 (0.7-1.2)510.9 (0.6-1.2)
Age at menopause (y)
    <45332310.9 (0.6-1.3)180.5 (0.3-0.8)50.6 (0.2-1.7)790.6 (0.5-0.8)610.6 (0.5-0.9)
    45-49670771.1 (0.8-1.5)500.7 (0.5-0.9)150.9 (0.5-1.8)2280.9 (0.7-1.1)1640.9 (0.7-1.1)0.34 (3)
    50-541,2611321.0 (Ref)1391.0 (Ref)281.0 (Ref)4801.0 (Ref)3421.0 (Ref)
    ≥55283311.1 (0.8-1.7)280.9 (0.6-1.4)71.3 (0.6-3.1)1101.0 (0.8-1.3)650.8 (0.6-1.2)
Height (cm)
    <160675671.0 (Ref)551.0 (Ref)131.0 (Ref)2241.0 (Ref)1401.0 (Ref)0.18 (3)
    160-1641,0351041.0 (0.7-1.4)991.2 (0.8-1.7)281.4 (0.7-2.7)3561.0 (0.9-1.3)2661.3 (1.0-1.6)
    165-1699001081.1 (0.8-1.6)781.0 (0.7-1.5)160.8 (0.4-1.8)3471.2 (1.0-1.4)2391.3 (1.0-1.6)
    ≥170455531.1 (0.7-1.6)541.4 (1.0-2.1)141.5 (0.7-3.2)2381.5 (1.2-1.9)1441.5 (1.1-1.9)
Recent BMI (kg/m2)
    <22.2477351.0 (Ref)451.0 (Ref)71.0 (Ref)1051.0 (Ref)791.0 (Ref)0.48 (4)
    22.2-24.0463411.3 (0.8-2.0)350.8 (0.5-1.3)20.3 (0.1-1.5)1281.3 (1.0-1.7)1041.4 (1.0-2.0)
    24.1-25.8480451.4 (0.9-2.2)400.9 (0.6-1.5)111.7 (0.7-4.5)1351.3 (1.0-1.8)981.3 (0.9-1.8)
    25.9-28.2489501.5 (0.9-2.3)370.9 (0.5-1.3)71.1 (0.4-3.1)1761.7 (1.3-2.3)1131.5 (1.1-2.1)
    ≥28.3501551.6 (1.0-2.5)451.0 (0.7-1.6)142.2 (0.9-5.6)2282.2 (1.7-2.8)1512.0 (1.4-2.7)
Adult weight gain (kg)**
    <0185130.7 (0.4-1.3)150.6 (0.3-1.1)10.3 (0.0-2.2)390.7 (0.5-1.1)360.8 (0.5-1.2)
    0-9.5518511.0 (Ref)631.0 (Ref)101.0 (Ref)1461.0 (Ref)1191.0 (Ref)0.064 (4)
    10-19.5611781.3 (0.9-1.8)390.5 (0.3-0.8)121.0 (0.4-2.4)2421.4 (1.1-1.8)1721.3 (1.0-1.7)
    20-29.5264361.4 (0.9-2.2)280.9 (0.6-1.4)71.4 (0.5-3.8)1141.6 (1.2-2.1)821.4 (1.0-1.9)
    ≥30111111.0 (0.5-2.1)110.8 (0.4-1.7)42.1 (0.6-6.8)812.7 (1.9-3.8)251.1 (0.7-1.7)
Mother or sister with breast cancer
    No2,3482791.0 (Ref)2371.0 (Ref)541.0 (Ref)9451.0 (Ref)6481.0 (Ref)0.33 (1)
    Yes236461.7 (1.2-2.3)391.7 (1.2-2.4)152.7 (1.5-4.9)1932.0 (1.7-2.5)1191.8 (1.4-2.3)
Operated due to benign breast disease
    No2,3692891.0 (Ref)2411.0 (Ref)601.0 (Ref)1,0121.0 (Ref)6711.0 (Ref)0.92 (1)
    Yes249431.5 (1.1-2.1)441.8 (1.2-2.5)111.9 (1.0-3.7)1451.4 (1.1-1.8)1151.7 (1.3-2.1)
  • NOTE: Recent, 1 year before data collection.

    Abbreviation: df, degrees of freedom.

  • * P value for association from case-case analysis for ER+PR+ compared with ERPR cancer, in a model adjusted for age, BMI, age at first birth, and tumor size.

  • Adjusted for age, BMI, and age at first birth where applicable.

  • Not adjusted for age at first birth.

  • § Adjusted for number of births, age, and BMI.

  • Women with unknown age at menopause and women using menopausal hormone therapy before menopause excluded.

  • Women ever using menopausal hormone therapy excluded.

  • ** Weight gain from 18 years to 1 year before data collection.