Table 1.

Age-adjusted incidence rates of, and numbers of women developing, invasive colorectal cancer in the WHI hormone trials and in corresponding observational study subcohorts, according to prior use of postmenopausal hormone therapy and hysterectomy status

Without uterus at enrollment
Clinical trial
Observational study
Prior HT*No
Yes
No
Yes
PlaceboCEEPlaceboCEENonuserCEENonuserCEE
No. of women27702769265925416541867744291905
Average age (y)63.863.663.463.665.163.465.764.2
Incidence rate1.521.651.211.471.310.730.861.66
No. of cases3032232665463324
With uterus at enrollment
Clinical trial
Observational study
Prior HT*No
Yes
No
Yes

Placebo
CEE/MPA
Placebo
CEE/MPA
Nonuser
CEE/MPA
Nonuser
CEE/MPA
No. of women602062772082222919668571056601046
Average age (y)63.463.463.062.664.761.064.864.3
Incidence rate1.641.001.530.700.971.081.060.72
No. of cases553517810927354
  • Abbreviation: HT, hormone therapy.

  • * Prior HT is defined relative to WHI enrollment in the clinical trial and nonuser group in the observational study, and defined relative to the beginning of the on-going hormone therapy episode at enrollment in the observational study user groups.

  • CEE, conjugated equine estrogens; CEE/MPA, conjugated equine estrogens plus medroxyprogesterone acetate.

  • Incidence rate per 1,000 person years, adjusted to the 5-y age distribution in the respective clinical trials.