Vaginal estrogen use does not increase the risk for cardiovascular disease or cancer in menopausal women, researchers say.
An analysis of data from the Women's Health Initiative Observational Study shows that in women with an intact uterus, the risks for stroke, invasive breast cancer, colorectal cancer, endometrial cancer, and pulmonary embolism/deep vein thrombosis were not significantly different between women using vaginal estrogen and nonusers, Carolyn J Crandall, MD, from the department of medicine at the University of California, Los Angeles, and colleagues write.
In fact, the risks for global index event (GIE) — defined as time to first occurrence of coronary heart disease, invasive breast cancer, stroke, pulmonary embolism, hip fracture, colorectal cancer, endometrial cancer, or death from any cause — were lower in users than in nonusers (GIE adjusted hazard ratio, 0.68; 95% CI, 0.55–0.86), the study authors report. The results were published online August 14 in Menopause.
Among women who had undergone hysterectomy, the risks for individual and overall GIE were not significantly different in users compared with nonusers of vaginal estrogen (adjusted hazard ratio, 0.94; 95% CI, 0.70–1.26).
"We did not observe an increased risk of cardiovascular disease or cancer among women using vaginal estrogen compared with nonusers," the researchers write. "These findings should provide reassurance to women and their health providers regarding the safety of vaginal estrogen and will help to inform menopausal [hormone-therapy] clinical decision-making."
Warning labels on low-dose vaginal estrogen preparations approved by the US Food and Drug Administration (FDA) are not based on clinical-trial evidence of vaginal estrogen "and may discourage the use of a highly effective local treatment for a common condition with adverse effects on quality of life," the authors warn. "Currently, the US FDA is considering a proposal to modify package labeling so that it better reflects the safety profile of vaginal estrogen," they add.
"These findings should reassure women and their healthcare providers that low-dose vaginal estrogen, which keeps blood levels within the normal postmenopausal range, is effective and safe for postmenopausal women who need relief from only vaginal symptoms," JoAnn Pinkerton, MD, executive director, North American Menopause Society, said in a statement. "The boxed warnings about the risk of heart disease, stroke, blood clots, and cancer do not apply to these low-dose vaginal therapies. Instead, women who experience bleeding or those with breast cancer should include their healthcare providers and oncologists in deciding about this option."
The prospective observational cohort study looked at data from 45,663 women enrolled in the WHI-OS, a nationwide study of 93,676 postmenopausal women aged 50 to 79 years conducted from 1993 to 2005. During a median follow-up of 7 years, none of the participants used systemic estrogen therapy.
The current study shows that women who used vaginal estrogen were more likely to be white (89.2% vs 79.8%), college graduates (46.3% vs 37.8%), have an annual household income of at least $100,000, and to have a body mass index of less than 25 kg/m2 (45.5% vs 35.9%). The researchers observed the same pattern when they stratified the data by hysterectomy status.
These results are consistent with prospective observational studies evaluating CHD, stroke, breast cancer, and endometrial cancer risk among vaginal estrogen users, the authors note. One study limitation was the fact that the researchers could not compare health outcomes among the different formulations of vaginal estrogen, such as the estradiol ring, vaginal estradiol tablet, and estrogen cream.
This research was supported by the National Heart, Lung, and Blood Institute, the National Institutes of Health and the US Department of Health and Human Services. Dr Crandall has disclosed no relevant financial relationships. Disclosures for the coauthors are listed in the paper.
Menopause. Published on August 14, 2017.
Menopause. Published on August 14, 2017. Abstract