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Another recent publication from the estrogen + progestin (E + P) arm of the Women’s Health Initiative (WHI) trial brings updated data on breast cancer [1]. The reason for the new paper lies in an extended, open follow-up period. The basic intervention time for the clinical trial was 5.6 years (standard deviation (SD) 1.3 years) (range 3.7–8.6 years), and the mean total follow-up period was 7.9 years (SD 1.4 years).In the E + P arm there were 385 cases of breast cancer (0.42% per year) vs. 293 cases in the placebo group (0.34% per year) (hazard ratio (HR) 1.25; 95% confidence interval (CI) 1.07–1.46; [i]p[/i] = 0.004). Breast cancers in the E + P group were similar in histology and grade to breast cancers in the placebo group but were more likely to be node-positive (HR 1.78; 95% CI 1.23–2.58;[i]p[/i] = 0.03). There were more deaths directly attributed to breast cancer (25 deaths (0.03% per year) vs. 12 deaths (0.01% per year); HR 1.96; 95% CI 1.00–4.04; [i]p[/i] = 0.049) as well as more deaths from all causes occurring after a breast cancer diagnosis (51 deaths (0.05% per year) vs. 31 deaths (0.03% per year); HR 1.57; 95% CI 1.01–2.48; [i]p[/i] = 0.045) among women who received E + P compared with women in the placebo group.


  • Amos Pines
    Department of Medicine T, Ichilov Hospital, Tel-Aviv, Israel


  1. Chlebowski RT, Anderson GL, Gass M, et al. Estrogen plus progestin and breast cancer incidence and mortality in postmenopausal women. JAMA 2010;304:1684-92.
  2. Huang Y, Malone KE, Cushing-Haugen KL, Daling JR, Li CI. Relationship between menopausal symptoms and risk of postmenopausal breast cancer. Cancer Epidemiol Biomarkers Prev 2011 Jan 18. Epub ahead of print.
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