To the Editor Dr Manson and colleagues presented long-term all-cause and cause-specific mortality from the Women’s Health Initiative (WHI) randomized trials.1 Consistent with previous WHI publications, they reported a discrepancy in breast cancer outcomes between women taking different formulations of hormone therapy: conjugated equine estrogens (CEE) alone or combined hormone therapy (CEE plus medroxyprogesterone acetate).2 Specifically, deaths from breast cancer were increased in users of combined hormone therapy (hazard ratio [HR], 1.44 [95% CI, 0.97-2.15]; P = .07) but reduced in women taking estrogen alone (HR 0.55, 95% CI, 0.33-0.92; P = .02).
Hickey M, McNamara HC, Mishra GD. Menopausal Estrogen Therapy and Breast Cancer Mortality. JAMA. 2018;319(2):193. doi:10.1001/jama.2017.18308