Carolyn J. Crandall, MD, MS, FACP Professor of Medicine at the David Geffen School of Medicine at University of California, Los Angeles received the best paper of the year award from the journal Menopause. The award was announced at the North American Menopause Society Annual Meeting in September 2019.  https://www.whi.org/Stories/WHI%20Paper%20Wins%20Award.aspx

The paper found that after menopause, up to half of women will experience symptoms of atrophic vaginitis. The symptoms of atrophic vaginitis include vaginal dryness, burning, and irritation, including pain with intercourse. These symptoms have negative effects on women's lives. There are many available preparations of vaginal estrogen therapies available to treat the symptoms of atrophic vaginitis. In this study, we examined data from 45,663 women in the WHI Observational Study to compare the occurrence of several important health outcomes among women using, versus women not using, vaginal estrogen therapy. We found that the risks of cardiovascular disease and cancer were not elevated among postmenopausal women using vaginal estrogen. These results are reassuring regarding the safety of these preparations. 

Crandall CJ, Hovey KM, Andrews CA, Chlebowski RT, Stefanick ML, Lane DS, Shifren J, Chen C, Kaunitz AM, Cauley JA, Manson JE. Breast cancer, endometrial cancer, and cardiovascular events in participants who used vaginal estrogen in the WHI Observational Study. Menopause. 2018 Jan;25(1):11-20. doi: 10.1097/GME.0000000000000956. Epub 2017 Aug 14.

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Long-term influence of estrogen plus progestin and estrogen alone use on breast cancer incidence: The Women’s Health Initiative randomized trials. Chlebowski RT, Anderson GL, Aragaki AK, et al
Oral presentation at the San Antonio Breast Cancer Symposium; December 10-14, 2019
San Antonio, Texas
https://thebms.org.uk/2019/12/whi-randomised-study-long-term-follow-up-results-december-2019-hrt-and-breast-cancer/

Researchers from the Women Health Initiative Randomised Trial (WHI) presented on the long-term breast cancer risk with HRT in women who took part in the WHI study at the San Antonio Breast Cancer Symposium (SABCS) in Texas on 13th December 2019.

A total of 27,347 women were included in this randomised study. Of these, 10,739 women who had undergone a hysterectomy were randomised to receive conjugated equine estrogen alone or placebo for an average of 7.2 years, while 16,608 women were randomised to receive conjugated equine estrogen plus medroxyprogesterone acetate or placebo for an average of 5.6 years.

Women in the estrogen only trial were followed up for an average of 16.1 years and had 520 breast cancer incidents included in the study. Women who received estrogen only HRT were noted to have a significant reduction in breast cancer incidence (HR 0.77, 95%CI 0.65-0.92. p=0.005) and a significant reduction in breast mortality (44% reduction) compared to placebo.

Women in the combined estrogen progestogen randomized trial were followed up for an average of 18.3 years and had 1003 breast cancer incidents included in the study. Women who received conjugated equine estrogen plus medroxyprogesterone acetate were noted to have a significant increase in breast cancer incidence (HR 1.29, 95%CI 1.14-1.47. p<0.001) as noted in the earlier reports from the WHI study. This increased risk persisted more than 10 years after discontinuing HRT. (HR 1.29, 95%CI 1.14-1.47. p<0.001). No statistically significant increase in breast cancer mortality was noted in women receiving conjugated equine estrogen plus medroxyprogesterone acetate compared to those who received placebo.