Table 2.

Association of endometrial cancer with oral contraceptive use, 1995–2013

Age adjustedaMultivariable adjustedb
ExposureCasesPerson-yearsRatecIRR95% CIIRR95% CI
OC use
 Never5779,59471.61.00Referent1.00Referent
 Ever243609,90639.80.720.53–0.980.860.63–1.18
  Former221489,40645.20.740.54–1.000.870.64–1.20
  Years since last used
   1–940174,34122.90.520.34–0.800.690.44–1.08
   10–1938134,45528.30.720.46–1.130.850.54–1.32
   20–2958105,04255.20.850.58–1.260.980.66–1.45
   ≥307762,163123.90.790.55–1.140.890.62–1.28
  Current22120,50018.30.610.36–1.030.690.40–1.20
 Duration (years)
  1–4165325,16750.70.840.61–1.150.980.71–1.35
  5–942142,58329.50.590.39–0.900.740.48–1.13
  ≥1024122,33919.60.370.22–0.600.450.27–0.74
Ptrend<0.0001Ptrend0.0002
 Recency (years) × Duration (years)e
  <10, <536118,12530.50.740.48–1.140.910.58–1.45
  <10, ≥522168,13313.10.340.20–0.580.450.26–0.76
  10–19, <52776,36735.40.960.59–1.581.090.66–1.80
  10–19, ≥51158,08718.90.410.21–0.800.510.26–0.99
  ≥20, <5102129,80878.60.850.60–1.180.950.68–1.34
  ≥20, ≥53337,39788.20.690.45–1.080.800.51–1.25
  • aAge-adjusted model stratified by age and study period.

  • bMultivariable model stratified by age and study period and adjusted for age at menarche, parity, menopausal status, estrogen-only FMH use, estrogen plus progestin FMH use, smoking, BMI, and vigorous physical activity.

  • cCrude rate per 100,000 person-years.

  • dYears since last use [Ptrend = 0.03 (age- and period adjusted), 0.43 (multivariable adjusted)].

  • eCross-tabulated recency and duration of use.