Endometrial Cancer in Women with Adenomyosis: An Underestimated Risk?

Minimizing blood loss in laparoscopic myomectomy with temporary occlusion of the hypogastric artery

Introduction

Uterine leiomyomas are common benign pelvic tumors. Currently, laparoscopic myomectomy (LM) is the preferred treatment option for women in the fertile age group with symptomatic myomas. The authors hypothesize that combining LM with a bilateral temporary occlusion of the hypogastric artery (TOHA) using vascular clips minimizes uterine blood flow during surgery and can significantly reduce surgery-associated blood loss.

Materials and methods

This single-center, prospective randomized study was conducted at the Department of Obstetrics and Gynecology, Municipal Emergency Clinical Hospital Timisoara, Romania. Patients aged between 18 and 49 who preferred laparoscopic myomectomy and wished to preserve fertility were included, provided they had intramural uterine leiomyomas larger than 4 cm in diameter that deformed the uterine cavity. The study analyzed data from 60 laparoscopic myomectomies performed by a single surgeon between January 2018 and December 2020. Patients were randomly assigned to either: "LM + TOHA" group (29 patients), and "LM" group (31 patients). The study's main objective was to evaluate the impact of TOHA on perioperative blood loss, expressed as mean differences in Hb (delta Hb).

Results

Delta Hb was statistically lower in the "LM + TOHA" group compared to "LM" group, with mean ± standard (min-max): 1.68 ± 0.67 (0.39-3.99) vs. 2.63 ± 1.06 (0.83-4.92) g/dL, respectively (p < 0.001). There was a statistically significant higher need for postoperative iron perfusion in the "LM" group, specifically 0 vs. 12 patients (p < 0.001), and lower postoperative anemia in "LM + TOHA" group (p < 0.001). Necessary artery clipping time was 10.62 ± 2.47 (7-15) minutes, with no significant impact on overall operative time: 110.2 ± 13.65 vs. 106.3 ± 16.48 (p = 0.21). There was no difference in the length of hospitalization or 12-month post-intervention fertility.

Discussion

Performing bilateral TOHA prior to laparoscopic myomectomy has proven to be a valuable technique in reducing surgery-associated blood loss, while minimizing complications during surgery, with no significant increase in the overall operative time.

Clinical trial registration

ISRCTN registry, (www.isrctn.com), identifier ISRCTN66897343.

Surgical restaging of patients with early‑stage endometrial cancer with lymphovascular invasion does not significantly impact their survival outcomes

Lymphovascular space invasion (LVSI) is considered to be a poor prognostic factor in endometrial cancer. However, management of patients with early-stage endometrial cancer with positive LVSI remains controversial. The main objective of the present study was to investigate whether surgical restaging of such patients has a significant effect on survival outcomes or may be otherwise omitted. A retrospective cohort study was conducted at the Gynaecologic Oncology Unit, Insitut Bergonie, Bordeaux, France for the period January 2003-December 2019. The present study included patients with definitive histopathological diagnosis of early-stage, grade 1-2 endometrial cancer with positive LVSI. Patients were divided into two groups: Those being restaged with pelvic and para-aortic lymphadenectomy (group 1) and those not restaged and receiving complementary therapy (group 2). The primary outcomes of the study were overall survival and progression-free survival. Epidemiological data, clinical and histopathological characteristics as well as complementary treatment received were also studied. Kaplan-Meier and Cox regression analyses were performed. Data from 30 patients were retrieved, of which restaging with lymphadenectomy was performed in 21 patients (group 1), while another 9 patients (group 2) were not restaged and received complementary therapy. Lymph node metastasis was observed in 23.8% of patients in group 1 (n=5). No significant difference was observed between groups 1 and 2 in terms of survival outcomes. The median overall survival was 91.31 months in group 1 and 90.61 months in group 2 [hazard ratio (HR), 0.71; 95% CI, 0.03-16.58; P=0.829]. The median disease-free survival was 87.95 months in group 1 and 81.52 months in group 2 (HR, 0.85; 95% CI, 0.12-5.91; P=0.869). In conclusion, restaging with lymphadenectomy did not alter prognosis of early-stage, LVSI-positive patients. As there was no clinical and therapeutic benefit, restaging with lymphadenectomy could be omitted in such patients.

Case report: Posterior reversible encephalopathy syndrome, an adverse effect of lenvatinib and pembrolizumab combination therapy, in a patient with advanced endometrial cancer

Background

Lenvatinib-pembrolizumab combination (LEAP) is an approved therapy in Japan for advanced endometrial cancer, based on the data from the KEYNOTE-775 clinical trial. We report a case of posterior reversible encephalopathy syndrome (PRES) in a patient who received LEAP therapy for advanced endometrial cancer.

Case presentation

A 53-year-old patient with stage IVB endometrial cancer having rectal metastases, after four cycles of paclitaxel-carboplatin therapy, was found to have increased rectal invasion, peritoneal dissemination, and multiple paraaortic lymph node metastases. She was treated with LEAP therapy and discharged on day 12 without adverse events, except for mild anemia on day 11 of treatment. She was carefully managed in the outpatient department, but on day 18, she was admitted to the emergency department with severely impaired consciousness and generalized seizures. Computed tomography of the head and lumbar tap showed no abnormal findings, and the seizures resolved with anticonvulsant medication alone. Based on a thorough physical examination and findings on magnetic resonance imaging (MRI), which showed high signal intensity in the left occipital lobe, encephalopathy, rather than encephalitis, was the likely diagnosis. Symptomatic improvement was observed, and pembrolizumab monotherapy was resumed.

Conclusions

If consciousness is impaired during LEAP treatment, it is necessary to differentiate between immunogenic encephalitis caused by pembrolizumab or encephalopathy caused by lenvatinib. MRI and lumbar tap can help in distinguishing between the two and diagnosing the responsible drug.

Spontaneous rupture of the uterus in the third trimester after high-intensity ultrasound ablation in adenomyosis: A case report

Adenomyosis is a benign uterine disease. Due to the higher incidence of adenomyosis and patients' demands for fertility, high-intensity ultrasound ablation has been widely used in gynecological patients with uterine fibroids and adenomyosis. Ultrasound ablation of lesions can help alleviate symptoms in patients without increasing the incidence of obstetric complications in subsequent pregnancies. High-intensity ultrasound ablation is not considered a risk factor for uterine rupture. However, we describe a case of adenomyosis treated with high-intensity ultrasound ablation presenting with uterine rupture in the third trimester. The patient underwent an emergency cesarean section to deliver the baby successfully and underwent uterine repair surgery. When treating patients with adenomyosis, care should be taken to protect the myometrium, endometrium, and serous layer to reduce the risk of uterine rupture.

Deep Infiltrating Endometriosis Malignant Invasion of Cervical Wall and Rectal Wall With Lynch Syndrome： A Rare Case Report and Review of Literature

Background

Malignant transformation of deep infiltrating endometriosis (DIE) invading the cervix and rectum is quite rare, especially in patients combined with Lynch syndrome (LS). We report a rare case of a 49-year-old perimenopausal woman with endometrioid carcinoma arising from the pouch of Douglas, invading the cervix and rectum 1 year after a unilateral salpingo-oophorectomy treatment for ovarian endometriosis. The genetic testing of the patient showed germline mutations in MSH2, which combined with the special family history of colorectal cancer of the patient, was also thought to be associated with LS. We have analyzed the reported cases of DIE malignant transformation over the last 10 years, and reviewed the relevant literature, in order to strengthen the clinical management of patients with endometriosis, particularly patients with DIE, and reveal a possible correlation between malignant transformation of endometriosis and LS.

Case Presentation

A 49-year-old perimenopausal woman presented with hypogastralgia, diarrhea, and intermittent fever for more than 1 month. A Transvaginal ultrasound (TVS) showed a cervix isthmus mass, and a magnetic resonance imaging (MRI) showed a mass in pouch of Douglas with high suspicion of malignancy, possibly invading the anterior wall of the rectum. Prior to surgery, the patient performed the ultrasound guided pelvic mass biopsy through the vagina, and the pathology of the mass showed endometrioid carcinoma. The patient received a gynecological–surgical laparotomy and enterostomy, and a histopathology revealed endometrioid carcinoma infiltrating the cervical wall and rectal wall. In the family genetic history of the patient, her mother and two sisters suffered from colorectal cancer, so lesion tissue and blood were taken for genetic testing, which showed a germline mutation in MSH2, with LS being considered. After the surgical treatment, the patient received six courses of paclitaxel–carboplatin chemotherapy. During the course of treatment, bone marrow suppression occurred, but was healed after symptomatic treatment. To date, the patient is generally in good health, and imaging examination showed no evidence of recurrence.

Conclusion

The risk of malignant transformation of endometriosis is increased in perimenopause and postmenopause, as DIE is a rare malignant transformation of endometriosis. DIE can invade other adjacent organs and cause poor prognosis, thus, comprehensive gynecological–surgical treatment should be necessary. In addition, if histopathology showed endometrioid carcinoma, the possibility of LS should be considered, and if necessary, immunohistochemical staining and gene detection should be improved to provide follow-up targeted therapy and immunotherapy.

Clinical analysis of 44 cases of atypical polypoid adenomyoma of the uterus

BACKGROUND

Atypical polypoid adenomyoma (APA) is a rare intrauterine polypoid lesion that occurs predominantly in premenopausal women. Although APA was previously considered a benign lesion and treated conservatively, an increasing number of cases show that APA has a high rate of recurrence or residual disease and that it precedes the development of carcinoma. The clinical management of APA remains to be established. The aim of this study was to analyse the clinicopathological features of APA and discuss its diagnosis and prognosis.

METHODS

Forty-four patients with APA were admitted to Beijing Obstetrics and Gynecology Hospital from 2005 to 2019, and their clinical and histopathologic features were evaluated. B-ultrasound was performed, and all the patients (n = 44) underwent hysteroscopy. Endometrium excision was performed by means of the four-step diagnosis and treatment method. Hysteroscopic transcervical resection (TCR) was performed in 5 patients with APA-H and 11 with APA-L. Except for one patient who underwent transcervical endometrial resection, all the patients underwent hysterectomy and salpingectomy or salpingo-oophorectomy. Data from a median follow-up of 42 months (ranging from 3 to 174 months) were available for these patients.

RESULTS

Pathological diagnosis were made according to the degree of abnormality of the APA surface glands, resulting in APA-L in 36 patients and APA-H in 8 patients. Among these patients, 28 (25 APA-L and 3 APA-H) were treated conservatively. The effect of the four-step diagnosis and treatment method as an APA therapy was excellent. During the follow-up, no evidence of recurrence was found.

CONCLUSIONS

For patients with intracavitary lesions > 1 cm, the hysteroscopic four-step diagnosis and treatment method and pathological diagnosis are the basis of clinical treatment. More than 30% of APA surface glands have complex structures characterized by branching and budding or other high-risk factors, such as endometrial hyperplasia, which are indications for hysterectomy. For patients who desire to become pregnant or to preserve the uterus, hysteroscopy with complete excision of the lesions should be the preferred treatment method. The patients should be treated and followed up closely with regular hysteroscopy and endometrial biopsy.

Primary low-grade extrauterine endometrial stromal sarcoma: analysis of 10 cases with a review of the literature

Background

This study aimed to analyze the clinical and pathological features of extrauterine endometrial stromal sarcoma (EESS) and explore an effective therapeutic regimen to reduce the recurrence rate in low-grade EESS patients.

Methods

Ten LG-EESS patients who were treated at the Chinese Academy of Medical Sciences Cancer Institute and Hospital from June 1999 to June 2019 were collected and analyzed.

Results

(1) Patient demographics are summarized in manuscript. Preoperative CA125 examination showed that 8 patients had a median level of 49.5 U/L (15.4–168.0 U/L). (2) All ten patients underwent tumor cytoreductive surgery. Five patients underwent optimal tumor resection and achieved an R0 resection. After the initial surgery, 7 patients who had multiple metastasis were treated with adjuvant chemotherapy, 2 patients with vaginal ESS were treated with chemotherapy and radiation therapy, and 6 patients with ER/PR positive received hormone therapy with or without chemotherapy. (2) Most EESS patients had multiple tumors. The omentum was the most commonly affected site, followed by the ovaries. (3) The median follow-up was 94 (range: 27–228) months, and recurrence was observed in 3 patients (n = 10, 30%) who underwent non-optimal surgery and no hormone therapy. The 5-year and 10-year DFS rates were both 70%, as shown in Fig. 2. OS was both 100% at 5 and 10 years.

Conclusion

As a conclusion, EESS is a rare disease and LG-EESS has a good prognosis. Surgery remains the available treatment for patients. LG-EESS has a risk of late recurrence which requires a long-term follow-up. With a limited sample size, our study shows optimal tumor reductive surgery and adjuvant hormone therapy may significantly reduce the risk of recurrence.

Transcriptomics of receptive endometrium in women with sonographic features of adenomyosis

BACKGROUND

Women with uterine adenomyosis seeking assisted reproduction have been associated with compromised endometrial receptivity to embryo implantation. To understand the mechanisms involved in this process, we aimed to compare endometrial transcriptome profiles during the window of implantation (WOI) between women with and without adenomyosis.

METHODS

We obtained endometrial biopsies LH-timed to the WOI from women with sonographic features of adenomyosis (n=10) and controls (n=10). Isolated RNA samples were subjected to RNA sequencing (RNA-seq) by the Illumina NovaSeq 6000 platform and endometrial receptivity classification with a molecular tool for menstrual cycle phase dating (beREADY®, CCHT). The program language R and Bioconductor packages were applied to analyse RNA-seq data in the setting of the result of accurate endometrial dating. To suggest robust candidate pathways, the identified differentially expressed genes (DEGs) associated with the adenomyosis group in the receptive phase were further integrated with 151, 173 and 42 extracted genes from published studies that were related to endometrial receptivity in healthy uterus, endometriosis and adenomyosis, respectively. Enrichment analyses were performed using Cytoscape ClueGO and CluePedia apps.

RESULTS

Out of 20 endometrial samples, 2 were dated to the early receptive phase, 13 to the receptive phase and 5 to the late receptive phase. Comparison of the transcriptomics data from all 20 samples provided 909 DEGs (p<0.05; nonsignificant after adjusted p value) in the adenomyosis group but only 4 enriched pathways (Bonferroni p value < 0.05). The analysis of 13 samples only dated to the receptive phase provided suggestive 382 DEGs (p<0.05; nonsignificant after adjusted p value) in the adenomyosis group, leading to 33 enriched pathways (Bonferroni p value < 0.05). These included pathways were already associated with endometrial biology, such as "Expression of interferon (IFN)-induced genes" and "Response to IFN-alpha". Data integration revealed pathways indicating a unique effect of adenomyosis on endometrial molecular organization (e.g., "Expression of IFN-induced genes") and its interference with endometrial receptivity establishment (e.g., "Extracellular matrix organization" and "Tumour necrosis factor production").

CONCLUSIONS

Accurate endometrial dating and RNA-seq analysis resulted in the identification of altered response to IFN signalling as the most promising candidate of impaired uterine receptivity in adenomyosis.

Anti-Mullerian Hormone (AMH) and adenomyosis: Mini-review of literature of the last 5 years

INTRODUCTION

Adenomyosis is a form of endometriosis characterized by the presence of endometrial tissue in the myometrium. The correlation between anti-Mullerian hormone (AMH) expression and adenomyosis is unclear. Few studies investigated this possible correlation with promising results. The aim of this mini-review is to illustrate the potential prognostic and therapeutic role of AMH in adenomyosis.

MATERIALS AND METHODS

A study protocol was completed conforming to the Preferred Reporting Items for Reviews and Meta-Analyses (PRISMA) guidelines for systematic reviews. We performed an electronic databases search from each database's inception from August 2017 to August 2022 for full-text articles and published abstracts. For database searches, the following main keywords were the following text words: "adenomyosis" or "uterine endometriosis" [Mesh] AND "AMH" or "anti-mullerian hormone".

RESULTS

From the literature search, 8 abstracts of studies were retrieved and independently screened for inclusion by three authors. It was found that the most common therapeutic strategies (such as adenomyomectomy and high-intensity focused ultrasound (HIFU) do not alter AMH levels. Moreover, a higher expression of the AMH receptor II was observed in adenomyotic tissue, hence a possible therapeutic use of AMH was hypothesized.

CONCLUSION

The available evidence shows an unclear relationship between adenomyosis and AMH. Probably, women with adenomyosis have lower levels of AMH and the surgical treatment (adenomyomectomy, HIFU) does not alter this characteristic, therefore in all of them, ovarian function is not influenced.

Contemporary Fertility-Sparing Management Options of Early Stage Endometrioid Endometrial Cancer in Young Nulliparous Patients

Incidence of endometrial cancer (EC) has been increasing in recent years, especially in high-income countries. The disease commonly affects peri- and postmenopausal women; however, about 5% of women are diagnosed with EC in their reproductive age. Due to both the increasing incidence of EC among reproductive age women and trends to delayed childbearing, fertility-sparing treatment for young patients with EC has become extremely important for researchers and practitioners. Because the classic treatment with total hysterectomy and bilateral saplingo-oophorectomy is not an appropriate approach for young women demanding fertility preservation, several fertility-sparing options have been developed and summarized in this review. Utilization of different medications and their combination (progestagens, gonadotropin releasing hormones analogues, and metformin in different formulations) are tested and found as efficient for fertility-sparing treatment. New minimally invasive surgical techniques, combined with progestagens, are also confirmed as valuable. There are many novel conservative and surgical treatment approaches under investigation. Assuming that molecular biomarkers can be both diagnostic and prognostic to assist in prediction of response to a certain therapy, prognostic risk groups' stratification along with specific biomarkers' identification will ensure low recurrence and decrease mortality rates in young women with EC.

Molecular Basis of Endometriosis and Endometrial Cancer: Current Knowledge and Future Perspectives

The human endometrium is a unique tissue undergoing important changes through the menstrual cycle. Under the exposure of different risk factors in a woman's lifetime, normal endometrial tissue can give rise to multiple pathologic conditions, including endometriosis and endometrial cancer. Etiology and pathophysiologic changes behind such conditions remain largely unclear. This review summarizes the current knowledge of the pathophysiology of endometriosis and its potential role in the development of endometrial cancer from a molecular perspective. A better understanding of the molecular basis of endometriosis and its role in the development of endometrial pathology will improve the approach to clinical management.

Mifepristone inhibited the expression of B7-H2, B7-H3, B7-H4 and PD-L2 in adenomyosis

BACKGROUND

The immune mechanism was shown to be involved in the development of adenomyosis. The aim of the current study was to evaluate the expression of the immune checkpoints B7-H2, B7-H3, B7-H4 and PD-L2 in adenomyosis and to explore the effect of mifepristone on the expression of these immune checkpoints.

METHODS

The expression of B7-H2, B7-H3, B7-H4 and PD-L2 in normal endometria and adenomyosis patient samples treated with or without mifepristone was determined by immunohistochemistry analysis.

RESULTS

In adenomyosis patient samples, the expression of B7-H2, B7-H3 and B7-H4 was increased in the eutopic and ectopic endometria compared with normal endometria, both in the proliferative and secretory phases. Moreover, the expression of B7-H2 and B7-H3 was higher in adenomyotic lesions than in the corresponding eutopic endometria, both in the proliferative and secretory phases. The expression of PD-L2 was higher in adenomyotic lesions than in normal endometria in both the proliferative and secretory phases. In the secretory phase but not the proliferative phase, the expression of B7-H4 and PD-L2 in adenomyotic lesions was significantly higher than that in the corresponding eutopic endometria. In normal endometria and eutopic endometria, the expression of B7-H4 was elevated in the proliferative phase compared with that in the secretory phase, while in the ectopic endometria, B7-H4 expression was decreased in the proliferative phase compared with the secretory phase. In addition, the expression of B7-H2, B7-H3, B7-H4 and PD-L2 was significantly decreased in adenomyosis tissues after treatment with mifepristone.

CONCLUSIONS

The expression of the immune checkpoint proteins B7-H2, B7-H3, B7-H4 and PD-L2 is upregulated in adenomyosis tissues and is downregulated with mifepristone treatment. The data suggest that B7 immunomodulatory molecules are involved in the pathophysiology of adenomyosis.

Upregulated microRNA let-7a accelerates apoptosis and inhibits proliferation in uterine junctional zone smooth muscle cells in adenomyosis under conditions of a normal activated hippo-YAP1 axis

BACKGROUND

Let-7a is a small non-coding RNA that has been found to take part in cell proliferation and apoptosis. The hippo-YAP1 axis, known as a tumour suppressor pathway, also plays an important role in cell proliferation and apoptosis. YAP1, TAZ, and phospho-YAP1 play key roles in actions of the hippo-YAP1 axis. Adenomyosis (ADS) is a proliferative disease leading to a large uterus in patients with prolonged illness. Abnormal proliferation of smooth muscle cells (SMCs) in the uterine endometrial-myometrial junctional zone (JZ) is an important reason for developing ADS. This study aimed to explore the expression levels of let-7a and components of the hippo-YAP1 axis in SMCs in the uterine endometrial-myometrial JZ in ADS and to explore the roles of let-7a and the hippo-YAP1 axis of JZ SMC proliferation and apoptosis in ADS.

METHODS

We collected JZ tissues for the primary culture of SMCs from 25 women diagnosed with ADS and 27 women without ADS. We used quantitative real-time polymerase chain reaction and western blotting to measure the mRNA and protein expression levels of let-7a, YAP1, TAZ, and phospho-YAP1 in ADS JZ SMCs. A CCK-8 assay and flow cytometry analysis of apoptosis were utilized to test the proliferation and apoptosis of JZ SMCs. The let-7a overexpression lentiviral vector GV280 was used to increase the expression level of let-7a. We added verteporfin to block the phosphorylation of components of the hippo-YAP1 axis.

RESULTS

We found that the let-7a level was decreased, while the YAP1 and TAZ levels were increased in ADS JZ SMCs. Upregulated let-7a affected the expression levels of components of the hippo-YAP1 axis, accelerated apoptosis, and inhibited proliferation in JZ SMCs. Furthermore, accumulated YAP1 led to increasing proliferation of JZ SMCs after verteporfin treatment to block the phosphorylation of components of the hippo-YAP1 axis. If components of the hippo-YAP1 axis were unphosphorylated, upregulated let-7a could not inhibit the proliferation of ADS JZ SMCs. Upregulated let-7a could not activate the hippo-YAP1 axis in verteporfin treatment.

CONCLUSIONS

Our findings suggest that the let-7a and hippo-YAP1 axis may act as important regulators of JZ SMCs proliferation, and upregulated let-7a may be an effective method to treat ADS.

Preoperative MRI and LDH in women undergoing intra-abdominal surgery for fibroids: Effect on surgical route

INTRODUCTION

Our institution implemented a preoperative protocol to identify high-risk cases for which power morcellation should be avoided.

MATERIAL AND METHODS

In this retrospective cohort study, an institutional protocol requiring preoperative Magnetic Resonance Imaging with diffusion-weighted imaging and serum Lactate Dehydrogenase levels was implemented. Chart review was performed including all women who underwent intra-abdominal surgery for symptomatic fibroids from 4/23/2013 to 4/23/2015.

RESULTS

A total of 1,085 women were included, 479 before and 606 after implementation of the Magnetic Resonance Imaging / Lactate Dehydrogenase protocol. The pre-protocol group had more post-menopausal women (4% vs. 2%, p = 0.022) and women using tamoxifen (2% vs. 0%, p = 0.022) than those in the post-protocol group, but baseline patient characteristics were otherwise similar between groups. Incidence of malignant pathological diagnoses did not change significantly over the time period in relation to protocol implementation. The rate of open surgery for both hysterectomy and myomectomy remained the same in the year preceding and the year following initiation of the protocol (open hysterectomy rate was 19% vs. 16% in pre- and post-protocol groups, respectively, P = 0.463, and open myomectomy rate was 10% vs. 9% rates in pre- and post-protocol groups, respectively, P = 0.776). There was a significant decrease in the use of power morcellation (66% in pre- and 50% in post-protocol cohorts, p<0.001) and an increased use of containment bags (1% in pre- and 19% in post-protocol cohort). When analyzing the subset of women who had abnormal Magnetic Resonance Imaging / and Lactate Dehydrogenase results, abnormal Magnetic Resonance Imaging results alone resulted in higher rates of open approach (65% for abnormal vs. 35% for normal). Similarly, a combination of abnormal Magnetic Resonance Imaging and Lactate Dehydrogenase tests resulted in higher rates of open approach (70% for abnormal and 17% for normal). Abnormal Lactate Dehydrogenase results alone did not influence route.

CONCLUSIONS

Rates of MIS procedures were decreased for women with abnormal preoperative Magnetic Resonance Imaging results. False positive results appear to be one of the main drivers for the use of an open surgical route.

Current and Future Roles of Circular RNAs in Normal and Pathological Endometrium

The uterine endometrium, which lines the mammalian uterus, is essential for embryo implantation. This lining undergoes significant changes during sexual and menstrual cycles. The endometrium is also associated with hormone-related diseases such as endometriosis and endometrial cancer. Circular RNAs (circRNAs) play a role in various biological processes. Recent studies have determined that circRNAs function in both normal and pathological endometrial environments. Here, we review high-throughput studies pertaining to circRNAs as well as individual circRNAs active in the endometrium, in order to explore the myriad functions of circRNAs in the endometrium and mechanisms underlying these functions, from panoramic and individual perspectives. Owing to their abundant expression, stability, and small size, circRNAs have displayed potential usefulness as diagnostic markers and treatment targets for endometrial-related diseases. Therefore, the specific role of circRNAs in the endometrium warrants systematic investigation in the future.