June 8th, 2010

Hormone Replacement with Estrogen Alone Does Not Compromise Breast Cancer Detection


Breast cancer detection by mammography among postmenopausal women who use hormone replacement therapy with estrogen alone does not appear to be compromised, according to the results of a study in the Journal of Clinical Oncology.1

Previous studies have indicated that combined hormone therapy with estrogen plus progestin increases the incidence of breast cancer and also compromises the detection of breast cancer, leading to delayed diagnosis.2 The Women’s Health Initiative trial that evaluated the use of estrogen alone in women previously treated with hysterectomy found that the incidence of breast cancer was not increased; however, there is limited information about the effects of estrogen therapy on breast cancer detection.

The Women’s Health Initiative trial randomly assigned 10,739 postmenopausal women with prior hysterectomy to receive either estrogen therapy or placebo. They performed screening mammography at baseline and annually and biopsies when indicated. The data indicated that the use of estrogen alone for five years resulted in the following:

  • One in 11 women had an otherwise avoidable mammogram that resulted in a recommendation for short-interval follow-up.
  • One in 50 women had an otherwise avoidable breast biopsy.
  • Clinically indicated breast biopsies were more common among the estrogen users, but less commonly led to a diagnosis of breast cancer.
  • Abnormal mammograms (those suggestive of malignancy) were not increased as a result of estrogen use.
  • There was no statistically significant difference in the number of invasive breast cancers diagnosed in the two groups.

The researchers concluded that the impact on breast cancer detection from hormone replacement with estrogen alone differs from that of combined hormone therapy with progesterone and estrogen (which results in a higher incidence of abnormal mammograms and compromised breast cancer detection). Estrogen alone does not appear to substantially compromise breast cancer detection, though it does result in some otherwise avoidable breast biopsies and short-interval follow-up mammograms.


1 Chlebowski RT, Anderson G, Manson JE, et al. Estrogen alone in postmenopausal women and breast cancer detection by means of mammography and breast biopsy. Journal of Clinical Oncology. 2010; 28: 2690-2697.

2 Chlebowski RT, Hendrix SL, Langer RD, et al. Influence of estrogen plus progestin on breast cancer and mammography in healthy postmenopausal women: The Women’s Health Initiative randomized trial. JAMA. 2003; 289: 3243-3253.


Tags: Uncategorized, UNM CC Features