Safety and Serum Estradiol Levels in Hormonal Treatments for Vulvovaginal Atrophy in Breast Cancer Survivors: A Systematic Review and Meta-Analysis

Effects of vaginal estrogen on serum estradiol during aromatase inhibitor therapy in breast cancer patients with vulvovaginal atrophy: a prospective trial

PURPOSE

This study aimed to analyze changes in serum estradiol (E2) levels during concurrent vaginal estradiol therapy and adjuvant letrozole in postmenopausal breast cancer (BC) patients with vulvovaginal atrophy (VVA). Secondary objectives included assessing the effects of therapy on vaginal atrophy, quality of life (QoL) and menopause-related symptoms.

METHODS

20 postmenopausal patients undergoing adjuvant letrozole therapy and experiencing VVA symptoms were treated with vaginal estradiol for 12 weeks. Gynecologic examination and symptom screening were conducted at baseline and after 12 weeks. Serum E2 levels were analyzed at baseline, and at two, four, eight, and 12 weeks. E2 levels were measured using both a routine liquid chromatography-tandem mass spectrometry (LC-MS/MS) method and a highly sensitive (hsE2-MS) LC-MS/MS method.

RESULTS

At baseline, serum E2 levels, measured with hsE2-MS, were below the lower limit of quantification (LLOQ) in all patients. E2 remained below LLOQ throughout the treatment period in three patients (15%). Persistent E2 elevation above LLOQ was observed in six patients (30%), while isolated E2 elevations occurred in 10 patients (50%). One patient experienced transient E2 elevation in two sporadic measurements. Serum E2 variations were shown by using both LC-MS/MS methods. Vaginal pH, vaginal maturation index (VMI), and VVA symptoms significantly improved during treatment.

CONCLUSION

Intravaginal estradiol therapy (10ug) during adjuvant letrozole resulted in transient increases in systemic E2 levels among early BC patients with VVA. Highly sensitive LC-MS/MS is a promising method for monitoring E2 levels during aromatase inhibitor (AI) therapy.

Vaginal estrogen use in breast cancer survivors: a systematic review and meta-analysis of recurrence and mortality risks

OBJECTIVE

To assess the risk of breast cancer recurrence, breast cancer-specific mortality, and overall mortality for breast cancer survivors receiving vaginal estrogen therapy for genitourinary syndrome of menopause.

DATA SOURCES

From the inception of each database to April 6th, 2024, a systematic literature search was conducted in Google Scholar, PubMed, EMBASE, CINAHL, NCBI, and Science Direct. A secondary search was conducted on September 26th, 2024 utilizing Google Scholar, PubMed, EMBASE, CINAHL, and Science Direct.

STUDY ELIGIBILITY CRITERIA

We identified studies that reported on breast cancer recurrence defined per individual review criteria and considered both local and distant recurrence.

STUDY APPRAISAL AND SYNTHESIS METHODS

Three reviewers evaluated studies with eligibility criteria in mind. Breast cancer recurrence was the primary outcome. The secondary outcomes included: breast cancer mortality and overall mortality. Pooled unadjusted odds ratios with 95% confidence intervals were calculated using a random-effects model. We assessed the 95% prediction intervals to calculate the likely range within which we can expect to observe future individual values, based on a current model or dataset. We calculated the fragility index to evaluate the robustness of the pooled estimates.

RESULTS

Of 5522 articles identified, 8 observational studies were included in this meta-analysis. The use of vaginal estrogen in patients with a history of breast cancer was not associated with an increased risk of breast cancer recurrence (6 articles, 24,060 patients, odds ratio, 0.48; 95% confidence interval, 0.23-0.98). There was no increase in the risk of breast cancer mortality (4 articles, 61,695 patients, odds ratio 0.60; 95% confidence interval 0.18-1.95). Lastly, there was no increase in overall mortality with use of vaginal estrogen in breast cancer survivors (5 articles 59,724, odds ratio 0.46; 95% confidence interval 0.42-0.49).

CONCLUSION

The use of vaginal estrogen in patients with a history of breast cancer does not appear to be associated with an increased risk of breast cancer recurrence, breast cancer-specific mortality, or overall mortality.

Safety of topical estrogen therapy during adjuvant endocrine treatment among patients with breast cancer: A meta-analysis based expert panel discussion

IMPORTANCE

Endocrine treatments, such as Tamoxifen (TAM) and/or Aromatase inhibitors (AI), are the adjuvant therapy of choice for hormone-receptor positive breast cancer. These agents are associated with menopausal symptoms, adversely affecting drug compliance. Topical estrogen (TE) has been proposed for symptom management, given its' local application and presumed reduced bioavailability, however its oncological safety remains uncertain.

OBJECTIVE

The present systematic review, meta-analysis and expert panel review aimed to evaluate the strength of the available evidence on the risk of recurrence and mortality when TE is utilised in congruence with TAM or AI treatment, among BC survivors.

DATA SOURCES

Six databases and two prospective registers, were interrogated from inception to January 3rd, 2024. Search terms were Breast cancer AND Hormone replacement therapy AND topical/vaginal oestrogen AND recurrence/mortality.

STUDY SELECTION

All study designs reporting the use vs. non-use of TE in breast cancer survivors receiving adjuvant endocrine treatment were included. Six observational studies were deemed eligible for inclusion.

DATA EXTRACTION AND SYNTHESIS

Sources of heterogeneity were explored using subgroup analysis by risk of bias, median follow-up period, node positivity and menopausal status. Trial sequential analysis was performed to quantify outcome reliability. A global expert panel was called to deliberate on the data, pinpoint areas of limited understanding, and determine the most important areas for future research.

MAIN OUTCOMES AND MEASURES

Risk ratio effect sizes (RR) and corresponding 95 % Confidence Intervals (CI) of breast cancer recurrence and mortality in survivors on endocrine treatment (TAM and/or AI) exposed to TE were reported. Expert panel appraisal of meta-analysis evidence with definition of current knowledge gaps and future research aims.

RESULTS

In 38 050 female patients receiving adjuvant endocrine treatment, of whom 1805 had been exposed to TE, TE exposure of those on AI, did not increase all-cause mortality (RR 0.99 [95 %CI 0.58, 1.69], I2 = 81 %, P = 0.96; moderate GRADE certainty). However, such exposure may convey an increased risk of recurrence (RR 2.51 [95 % CI 1.10, 5.72], I2 = 9 %, P = 0.03; low-GRADE certainty). Exposure to TE during TAM did not increase either recurrence risk or all-cause mortality. Clinical factors such as lymph node positivity at the time of diagnosis and menopausal status and follow-up time appeared to be significant confounders.

CONCLUSIONS AND RELEVANCE

The use of TE does not appear to increase either recurrence or mortality risk among BC survivors treated with TAM. An increased recurrence risk, without an increase in mortality, cannot be ruled out when TE is used during AI.

Development and Bioavailability Assessment of an Estriol-Containing Vaginal Hydrogel

Genitourinary syndrome of menopause (GSM) affects a significant percentage of postmenopausal women and manifests as vaginal dryness, irritation, and urinary discomfort, typically treated with vaginal estrogens. Hydrogels are preferred over creams due to their superior comfort and mucoadhesive properties. This study introduces a novel vaginal gel formulation containing hydroxyethyl cellulose (HEC) and estriol-hydroxypropyl-β-cyclodextrin complex (E3-HPBCD) for the treatment of GSM. The estriol (E3) release profile of the gel was evaluated using a Franz diffusion cell system, and its permeability was tested on reconstructed human vaginal epithelium. Biocompatibility was assessed using (3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyltetrazolium bromide) (MTT), lactate dehydrogenase (LDH) assays, and real-time cell analysis (RTCA) on human skin keratinocyte (HaCaT) cells, which showed increased cell viability and no obvious cytotoxicity. The results indicated that efficient E3 release and satisfactory epithelial permeability with HPBCD provide the bioavailability of E3. These results suggest the potential of the gel as a biocompatible and effective alternative for the treatment of GSM. Further studies are required to assess the long-term safety and clinical efficacy.

New potential selective estrogen receptor modulators in traditional Chinese medicine for treating menopausal syndrome

Women go through several predictable conditions and symptoms during menopause that are caused by age, changes in sex hormone levels, and other factors. Conventional menopause hormone therapy has raised serious concerns about the increased risks of cancers, blood clots, depression, etc. Selective estrogen receptor modulators (SERMs) that can be both agonists and antagonists of estrogen receptors in a tissue-specific manner are being developed to reduce the health concerns associated with menopause hormone therapy. Here, we have searched the Chinese national traditional Chinese medicine (TCM) patent database to identify potential SERM-like compounds with reduced health risks. TCM has been widely used for treating complex symptoms associated with menopause syndrome and thus can be a particularly rich source for pharmaceutical alternatives with SERM properties. After extensive literature review and molecular simulation, we conclude that protopanaxatriol, paeoniflorin, astragalin, catalpol, and hyperoside among others may be particularly promising as SERM-like compounds in treating the menopausal syndrome. Compounds in TCM hold promise in yielding comparable outcomes to hormone therapy but with reduced associated risks, thus presenting promising avenues for their clinical applications.

The Concept behind the Suitability of Menstrual Blood-Derived Stem Cells for the Management of Vaginal Atrophy among BRCA Mutation Carriers after RRSO

Risk-reducing bilateral salpingo-oophorectomy (RRSO) is recommended for breast cancer gene 1 (BRCA1) and 2 (BRCA2) mutation carriers. A major consequence of RRSO is surgical menopause associated with severe menopausal symptoms, mostly genitourinary complaints. Due to the inherent breast cancer risk, estrogen-based therapies are generally avoided in these patients. So far, the non-hormonal approaches available are not efficient to successfully treat the disabling vaginal atrophy-related symptoms. In regenerative medicine, mesenchymal stem cells (MSC) are the most frequently used cell type due to their remarkable and regenerative characteristics. Therapies based on MSC have revealed positive outcomes regarding symptoms and signs associated with vaginal atrophy by promoting angiogenesis, vaginal restoration, and the proliferation of vaginal mucosa cells. Menstrual blood-derived stem cells (MenSC) are a novel source of MSC, with promising therapeutic potential directly linked to their high proliferative rates; low immunogenicity; non-invasive, easy, and periodic acquisition; and almost no associated ethical issues. In this review, we update the current knowledge and research regarding the potential value of previously preserved MenSC in the therapy of vaginal atrophy among BRCA mutation carriers subjected to RRSO.