medwireNews: The use of vaginal estrogen therapy to alleviate genitourinary symptoms of menopause does not appear to increase the risk for early breast cancer-specific mortality among women with the disease, suggests a large cohort study.
“Findings of this study may provide some reassurance to clinicians and support the guidelines suggesting that vaginal estrogen therapy can be considered in patients with breast cancer and genitourinary symptoms if nonhormonal treatments were unsuccessful,” writes the research team in JAMA Oncology.
Chris Cardwell (Queen’s University Belfast, UK) and associates drew on the cancer registries in Scotland and Wales to identify 49,237 women aged 40–79 years with a new diagnosis of breast cancer during 2010–2017 and 2000–2016, respectively, who were followed up until 2020 for breast cancer-specific mortality.
Data from the Scottish Prescribing Information System and Welsh general practice records showed that 5% of the cohort used vaginal estrogen therapy (such as estriol creams and estradiol tablets) after diagnosis and 1% used systemic hormone replacement therapy (HRT).
Vaginal estrogen therapy use did not significantly increase breast cancer-specific mortality, if anything, its use was associated with a “small decrease” in risk in the pooled, fully adjusted model, report the study authors, at a hazard ratio (HR) of 0.77 relative to no HRT use.
They add that “the associations were similar in most sensitivity analyses,” such as in models restricted to women with estrogen receptor-positive disease or those using aromatase inhibitors (HRs=0.88 and 0.72, respectively).
“The null finding is similar to results of a Danish study involving 8461 patients with breast cancer that observed no association between vaginal estrogen therapy and cancer recurrence,” say Cardwell et al.
Discussing the results, they say that the strengths of the study include “the large population-based cohorts with up to 20 years of follow-up with linked prescribing or dispensing records, which eliminated recall bias and captured all HRT prescriptions.”
Nevertheless, the study does have limitations, they acknowledge, such as the inability to confirm medication adherence and investigate the effects on later breast cancer-specific mortality.
“Moreover, patients who received treatment for genitourinary syndrome of menopause may have lower estradiol levels and/or better compliance to endocrine therapies and thus have lower breast cancer–specific mortality,” writes the team.
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