Association of Menopausal Hormone Therapy With Breast Cancer Incidence and Mortality During Long-term Follow-up of the Women’s Health Initiative Randomized Clinical Trials

In long-term follow-up study of 2 trials (n=27,347) prior randomised use of conjugated equine estrogen+medroxyprogesterone acetate vs placebo in women with intact uterus was significantly linked to higher breast cancer (BC) incidence but no significant difference in BC mortality.

SPS commentary:

In this group the annualized incidence of breast cancer was 0.45% vs 0.36%; HR, 1.28). In contrast, prior randomised use of conjugated equine estrogen alone, vs. placebo, among women who had had hysterectomy was significantly linked to lower breast cancer incidence (annualised incidence, 0.30% vs 0.37%; HR, 0.78); and lower breast cancer mortality (annualised mortality, 0.031% vs 0.046%; HR, 0.60).


According to an editorial, for postmenopausal women with a history of hysterectomy, estrogen alone may confer a lower risk of the development of breast cancer and improved breast cancer–specific survival, but age, severity of menopausal symptoms, CVD, thromboembolic disease, osteoporosis leading to hip fracture, and colorectal cancer, may also be considered in the decision. It suggests that given this multifactorial decision, these latest WHI data are unlikely to lead to use of hormone therapy for the sole purpose of breast cancer risk reduction but can provide some reassurance to women taking estrogen-alone that they are not elevating their breast cancer risk over time.


Journal of the American Medical Association

Resource links: