Table 2.

Numbers of women diagnosed with colorectal cancer, HR estimates and 95% CIs from the WHI postmenopausal hormone therapy trial and observational study for CEE and for CEE plus MPA

CEENonuserHR*CEE/MPANonuserHR* (95% CI)
Clinical trial58531.12 (0.77-1.63)43720.56 (0.38-0.81)
Observational study70980.80 (0.53-1.20)311441.15 (0.74-1.79)
  • * HRs in the clinical trial are from a Cox regression stratified by age group at enrollment, dietary modification trial randomization, and prior colorectal cancer, with assignment to the calcium and vitamin D trial as a time-dependent covariate. HRs in the observational study from a Cox regression model stratified by age group at enrollment, prior colorectal cancer, and prior postmenopausal hormone therapy, and adjusted for age (linear), body mass index, education, cigarette smoking, alcohol consumption, bilateral oophorectomy, type and duration of prior hormone therapy, family history of colorectal cancer, waist circumference, height, history of polyp removal, dietary selenium intake, nonsteroidal anti-inflammatory drug use, and prior oral contraceptive use. HR regression coefficients were estimated separately for prior postmenopausal therapy users and nonusers.