Effect of oral phytoestrogens on endometrial thickness and breast density of perimenopausal and postmenopausal women: A systematic review and meta-analysis

Guideline No. 451: Asymptomatic Endometrial Thickening in Postmenopausal Women

OBJECTIVE

To formulate strategies for clinical assessments for endometrial thickening on ultrasound in a postmenopausal woman without bleeding.

TARGET POPULATION

Postmenopausal women of any age.

OUTCOMES

To reduce unnecessary invasive interventions and investigations in women with asymptomatic endometrial thickening while selectively investigating women at risk for endometrial cancer.

BENEFITS, HARMS, AND COSTS

It is anticipated that the adoption of these recommendations would save postmenopausal women unnecessary anxiety, pain, and risk of procedural complications. It is also expected to decrease the cost to the health care system by eliminating unnecessary interventions.

EVIDENCE

English language articles from Medline, Cochrane, and PubMed databases for relevant peer-reviewed articles dating from 1995 to 2022 (e.g., asymptomatic endometrial thickness, endometrial cancer, postmenopausal bleeding, transvaginal ultrasound, endometrial biopsy, cervical stenosis, hormone therapies and the endometrium, tamoxifen, tibolone, aromatase inhibitors). Results were restricted to systematic reviews and meta-analyses, randomized controlled trials/controlled clinical trials, and observational studies.

VALIDATION METHODS

The authors rated the quality of evidence and strength of recommendations using the Grading of Recommendations Assessment, Development and Evaluation (GRADE) approach. See Appendix A (Tables A1 for definitions and A2 for interpretations of strong and conditional [weak] recommendations).

INTENDED AUDIENCE

Physicians, including gynaecologists, obstetricians, family physicians, radiologists, pathologists, and internists; nurse practitioners and nurses; medical trainees, including medical students, residents, and fellows; and other providers of health care of the postmenopausal population.

SOCIAL MEDIA ABSTRACT

Postmenopausal women often have a thickening of the lining of the uterus found during ultrasound. Without bleeding, an endometrium <11 mm is rarely a serious problem but should be evaluated by a health care provider.

SUMMARY STATEMENTS

RECOMMENDATIONS.

Flaxseed Ethanol Extracts’ Antitumor, Antioxidant, and Anti-Inflammatory Potential

The antitumoral, antioxidant, and anti-inflammatory effects of flaxseed ethanol extract was screened. Phytochemical analysis was performed by measuring the total phenolic content and by HPLC-DAD-ESI MS. In vitro antiproliferative activity was appreciated by MMT test of four adenocarcinomas and two normal cell lines. In vitro, antioxidant activity was evaluated by DPPH, FRAP, H₂O₂, and NO scavenging tests. The in vivo growth inhibitory activity against Ehrlich ascites carcinoma (EAC) in female BALB/c mice was determined using the trypan blue test. In EAC mice serum and ascites total oxidative status, total antioxidant reactivity, oxidative stress index, malondialdehyde, total thiols, total nitrites, 3-nitrotyrosine, and NFkB were measured. The phytochemical analysis found an significant content of phenols, with lignans having the highest concentration. The extract had an significant in vitro antioxidant effect and different inhibitory effects on different cell lines. After treatment of EAC mice with flaxseeds extract, body weight, ascites volume and viable tumour cell count, serum and ascites oxidative stress, and inflammatory markers decreased significantly. The ethanol flaxseeds extract has potential antiproliferative activity against some ovary and endometrial malignant cells and EAC. This effect can be attributed to the phenols content, and its antioxidant and anti-inflammatory activity.

Influence of phytoestrogens on endometrial thickness: a systematic review and meta-analysis

The objective of this systematic review was to evaluate the influence of the use of phytoestrogens on variations in endometrial thickness in postmenopausal women. Randomized controlled trials were searched in the following electronic databases until March 2020: MEDLINE, Embase, Cochrane Library, Web of Science and LILACS. We used the terms 'phytoestrogens' and 'endometrium' or 'endometrial hyperplasia' to search for relevant trials. The data were analyzed using RevMan 5.3 software. A total of 10 studies involving 1476 patients were included. The difference in endometrial thickness was evaluated in 10 studies, with a total of 805 participants in the phytoestrogen group and 761 in the control group. Such a difference was not significant between groups after 3 months (standardized mean difference [SMD] 0.00, 95% confidence interval [CI] - 0.37 to 0.37; I² = 63%), 6 months (SMD -0.30, 95% CI -0.79 to 0.19; I² = 70%), 12 months (SMD -0.02, 95% CI 0.22 to -0.18; I² = 0%) and 24 months (SMD -0.09, 95% CI -0.25, 0.08; I² = 0%) of use. Our meta-analysis shows no changes in endometrial thickness in women using phytoestrogens. Evidence is still uncertain owing to the presence of heterogeneity among the studies currently available, whose reported outcomes cover a period between 3 and 6 months.

[Non-hormonal alternatives for the management of menopausal hot flushes. Postmenopausal women management: CNGOF and GEMVi clinical practice guidelines]

One of the major symptoms of climacteric syndrome is hot flushes (HF). They are most often experienced as very disabling. Estrogen therapy is the most effective treatment. However, it may be contraindicated in some women. The aim of this article is to provide a review of the scientific literature on pharmacological and non-pharmacological alternatives in this context. Only randomized trials and meta-analyses of randomized trials were considered. This review shows that some treatments usually used in non-gynecological or endocrinological disease have significant effect in reducing the frequency and/or severity of HF. Hence, some selective serotonin reuptake inhibitors (paroxetine, citalopram and escitalopram), serotonin and norepinephrine reuptake inhibitors (venlafaxine, desvenlafaxine) gabapentin, pregabalin and clonidine have a statistically effect as compared with placebo in reducing, the frequency and/or severity of HF. Some phytoestrogens, such as genistein, may also reduce the frequency of HF. Regarding non-pharmacological interventions, hypnosis, acupuncture or yoga have been analyzed with significant beneficial results, even if their evaluation is difficult by the absence of a good placebo group in most trials. By contrast, other approaches, both pharmacological or non-pharmacological, appear to be ineffective in the management of HT. These include homeopathy, vitamin E, alanine, omega 3, numerous phytoestrogens (red clover, black cohosh…), primrose oil, physical activity. In women suffering from breast cancer, several additional problems are added. On the one hand because all phytoestrogens are contraindicated and on the other hand, in patients using tamoxifen, because the molecules, that interact with CYP2D6, are to be formally avoided because of potential interaction with this anti-estrogen treatment. In conclusion, several pharmacological and non-pharmacological alternatives have significant efficacy in the management of severe HF.

The effects of phytoestrogens on postmenopausal health

Phytoestrogens are a group of non-steroidal polyphenolic plant-based substances, commonly used for the treatment of menopause-related conditions. They have both genomic and non-genomic effects, displaying weak affinity for estrogen receptors (ER) and preferentially binding to ER-B over ER-A. However, evidence for the benefits of phytoestrogen consumption has been limited. We conducted a review of recent literature, focusing on systematic reviews and meta-analyses reporting on postreproductive health effects of phytoestrogens. While many trials concerning dietary and supplementary phytoestrogens have been conducted, evidence of clinical efficacy is heterogeneous and inconclusive. There appears to be reduction in the vasomotor symptoms of menopause with phytoestrogen intake; however, it is likely small and slow in onset. Phytoestrogens also appear to improve bone mineral density and markers of cardiovascular risk; however, there is inadequate research regarding long-term outcomes. There appear to be no harmful effects of phytoestrogens on breast, endometrial cancer or colorectal cancer and phytoestrogens intake may in fact be protective. Research regarding the effect of phytoestrogens on cognition is mixed, with most studies reporting no significant association. Overall, individual variations in the metabolism of phytoestrogens and age-related genomic effects may account for the considerable variability in the measured effects of phytoestrogens.

Is There Such a Thing as "Anti-Nutrients"? A Narrative Review of Perceived Problematic Plant Compounds

Plant-based diets are associated with reduced risk of lifestyle-induced chronic diseases. The thousands of phytochemicals they contain are implicated in cellular-based mechanisms to promote antioxidant defense and reduce inflammation. While recommendations encourage the intake of fruits and vegetables, most people fall short of their target daily intake. Despite the need to increase plant-food consumption, there have been some concerns raised about whether they are beneficial because of the various ‘anti-nutrient’ compounds they contain. Some of these anti-nutrients that have been called into question included lectins, oxalates, goitrogens, phytoestrogens, phytates, and tannins. As a result, there may be select individuals with specific health conditions who elect to decrease their plant food intake despite potential benefits. The purpose of this narrative review is to examine the science of these ‘anti-nutrients’ and weigh the evidence of whether these compounds pose an actual health threat.

Genistein as Potential Therapeutic Candidate for Menopausal Symptoms and Other Related Diseases

Plant-derived compounds have recently attracted greater interest in the field of new therapeutic agent development. These compounds have been widely screened for their pharmacological effects. Polyphenols, such as soy-derived isoflavones, also called phytoestrogens, have been extensively studied due to their ability to inhibit carcinogenesis. These compounds are chemically similar to 17β-estradiol, and mimic the binding of estrogens to its receptors, exerting estrogenic effects in target organs. Genistein is an isoflavone derived from soy-rich products and accounts for about 60% of total isoflavones found in soybeans. Genistein has been reported to exhibit several biological effects, such as anti-tumor activity (inhibition of cell proliferation, regulation of the cell cycle, induction of apoptosis), improvement of glucose metabolism, impairment of angiogenesis in both hormone-related and hormone-unrelated cancer cells, reduction of peri-menopausal and postmenopausal hot flashes, and modulation of antioxidant effects. Additionally, epidemiological and clinical studies have reported health benefits of genistein in many chronic diseases, such as cardiovascular disease, diabetes, and osteoporosis, and aid in the amelioration of typical menopausal symptoms, such as anxiety and depression. Although the biological effects are promising, certain limitations, such as low bioavailability, biological estrogenic activity, and effects on target organs, have limited the clinical applications of genistein to some extent. Moreover, studies report that modification of its molecular structure may eliminate the biological estrogenic activity and its effects on target organs. In this review, we summarize the potential benefits of genistein on menopause symptoms and menopause-related diseases like cardiovascular, osteoporosis, obesity, diabetes, anxiety, depression, and breast cancer.