Table 3.

Adjusted hazard ratios (95% CI) for the associations of incident endometrial cancer with baseline IGF-I, free IGF-I, insulin, IGFBP-3, glucose, HOMA index, and endogenous estradiol levels

Quartile 1Quartile 2Quartile 3Quartile 4Ptrend*
Total IGF-I
    Quartile cut points (ng/mL)<94.294.2 to <119.6119.6 to <151.0≥151.0
    Cases (n)54695473
    Age adjusted1.001.14 (0.72-1.82)0.73 (0.45-1.18)1.01 (0.63-1.59)0.60
    Age + estradiol + HT1.001.26 (0.78-2.05)0.81 (0.50-1.32)1.27 (0.78-2.06)0.73
    Age + BMI1.001.14 (0.70-1.86)0.71 (0.43-1.17)1.10 (0.67-1.79)0.63
Free IGF-I
    Quartile cut points (ng/mL)<0.210.21 to <0.360.36 to <0.55≥0.55
    Cases (n)70636546
    Age adjusted1.000.75 (0.48-1.18)0.76 (0.49-1.20)0.55 (0.34-0.88)0.02
    Age + estradiol + HT1.000.82 (0.52-1.31)0.90 (0.56-1.44)0.62 (0.38-1.01)0.09
    Age + BMI1.000.72 (0.45-1.16)0.78 (0.49-1.26)0.60 (0.36-0.98)0.04
Insulin
    Quartile cut points (μIU/mL)<3.63.6 to <5.75.7 to <9.5≥9.5
    Cases (n)59546168
    Age adjusted1.000.88 (0.56-1.39)1.11 (0.70-1.74)1.37 (0.87-2.16)0.11
    Age + estradiol + HT1.000.87 (0.54-1.38)1.13 (0.71-1.81)1.27 (0.79-2.03)0.21
    Age + BMI1.000.95 (0.59-1.52)1.25 (0.75-2.07)1.54 (0.88-2.67)0.05
IGFBP-3
    Quartile cut points (ng/mL)<3604.03604.0 to <4053.64053.6 to <4583.5≥4583.5
    Cases (n)65525776
    Age adjusted1.000.72 (0.45-1.15)0.71 (0.45-1.12)0.88 (0.57-1.37)0.65
    Age + estradiol + HT1.000.74 (0.46-1.20)0.74 (0.47-1.18)0.87 (0.55-1.38)0.63
    Age + BMI1.000.70 (0.43-1.15)0.67 (0.42-1.08)0.86 (0.53-1.38)0.48
Glucose
    Quartile cut points (mg/dL)<86.086.0 to <91.591.5 to <100≥100
    Cases (n)60705465
    Age adjusted1.001.13 (0.72-1.78)0.77 (0.48-1.22)0.92 (0.58-1.45)0.38
    Age + estradiol + HT1.001.13 (0.71-1.80)0.75 (0.46-1.21)0.89 (0.55-1.44)0.33
    Age + BMI1.001.08 (0.68-1.74)0.72 (0.44-1.18)0.76 (0.46-1.26)0.22
HOMA-IR index
    Quartile cut points<0.710.71 to <1.141.14 to <1.93≥1.93
    Cases (n)58596263
    Age adjusted1.000.83 (0.53-1.30)1.11 (0.70-1.75)1.24 (0.77-1.98)0.21
    Age + estradiol + HT1.000.86 (0.54-1.37)1.12 (0.70-1.79)1.20 (0.74-1.95)0.31
    Age + BMI1.000.85 (0.53-1.35)1.18 (0.72-1.95)1.29 (0.73-2.29)0.32
Estradiol
    Tertile cut points (pg/mL)<8.08.0 to <14.0≥14.0N/A
    Cases (n)235462N/A
    Age adjusted1.002.05 (1.16-3.64)3.61 (2.02-6.43)N/A<0.001
    Age + BMI1.001.89 (1.06-3.38)3.16 (1.71-5.81)N/A<0.001
  • Abbreviation: N/A, not applicable.

  • * Significance tests for trend were calculated using ordinal quantile variables (1-4 for quartile and 1-3 for tertile) entered into the model as a single continuous variable.

  • Reference category.

  • Among non–hormone therapy users only.