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. Author manuscript; available in PMC: 2015 Nov 1.
Published in final edited form as: Steroids. 2014 Jun 6;90:53–59. doi: 10.1016/j.steroids.2014.06.001

Table 4.

Selected Cancer Outcomes in the Women's Health Initiative Hormone Therapy Randomized Trials

Cancer category Estrogen plus progestin trial Estrogen alone trial
HR (95% CI) P HR (95% CI) P
Invasive breast cancer
    Incidence 1.25 (1.07-1.46) 0.004 0.71 (0.62-0.95) 0.02
    Death from breast cancer 1.96 (1.00-4.04) 0.049 0.37 (0.13-0.91)2 0.03
Colorectal cancer
    Incidence 0.72 (0.56-0.94) 0.01 1.12 (0.77-1.63) 0.55
    Death from colorectal cancer 1.29 (0.78-2.11) 0.32 0.99 (0.50-1.96) 0.99
Lung cancer
    Incidence 1.23 (0.92-1.63) 0.16 1.17 (0.81-1.69) 0.39
    Death from lung cancer 1.71 (1.16-2.52) 0.01 1.07 (0.66-1.72) 0.79
Endometrial cancer 0.37 (0.49-0.91) 0.007 NA NA

1) Hazard ratios (HR) are from Cox proportional hazards regression models, stratified by age, randomization group in the Women's Health Initiative dietary modification trial and prior disease when applicable. CI indicates confidence interval; all analyses start at time of randomization. Intervention duration was 5.6 yrs (mean) in the oestrogen plus progestin trial and 7.1 yrs (mean) in the oestrogen alone trial.

2) Results as published for E plus P: breast cancer (Chlebowski 2010 JAMA), colorectal cancer (Simon 2012), lung cancer (Chlebowski 2009 Lancet), endometrial cancer (Manson 2013), for E alone:breast cancer (Anderson 2012), colorectal cancer (Ritenbaugh 2008), lung cancer (Chlebowski 2010 JNCI).