Clinical patterns and genomic profiling of recurrent 'ultra-low risk' endometrial cancer

Aberrant nuclear β-catenin distribution does not prognosticate recurrences of endometrioid endometrial cancers - A retrospective single-institutional study

OBJECTIVE

Aberrant β-catenin distribution has been theorized as a predictive biomarker for recurrence in early stage, low grade endometrioid endometrial cancer.

METHODS

This retrospective single-institution cohort study reviewed 410 patients with endometrial cancer from May 2018 to May 2022. Only endometrioid histology was included. Demographic and clinicopathological data were collected from the medical records. Univariate and multivariate logistic regressions, and sensitivity analyses for early stage, low grade and no specific molecular profile (NSMP) tumors were performed.

RESULTS

297 patients were included for analysis. Most patients were over 60 years old, White, and with a BMI >30 and early stage low grade disease. Aberrant β-catenin distribution was found in 135 patients (45.5%) and wild type membranous β-catenin distribution in 162 (54.5%). While TP53 mutation correlated with endometrial cancer recurrence in this cohort (OR = 4.78), aberrant β-catenin distribution did not correlate in the overall population (OR = 0.75), the early stage low grade cancers (OR = 0.84), or the NSMP group (OR = 1.41) on univariate or multivariate analysis. No correlation between β-catenin distribution and local (OR = 0.61) or distant recurrences (OR = 0.90) was detected.

CONCLUSIONS

Aberrant β-catenin distribution did not significantly correlate with recurrence in endometrioid endometrial cancer, nor in the early stage, low grade and NSMP sub-cohorts.

Pulmonary metastasis of stage I, low-grade endometrioid carcinoma: two case reports and the literature review

Endometrial cancer (EC) is the most common malignant tumor of the female reproductive system, and the majority of ECs are low histological grade and confined to the uterus, resulting in a good prognosis. However, metastasis to the lung from a low-grade and early-stage endometrial endometrioid carcinoma (EEC) is extremely rare. Therefore, it is crucial to accurately differentiate between primary pulmonary malignancy and extra-thoracic malignancy presenting as metastatic disease, and flexible bronchoscopy with tissue acquisition plays a key role in this process. Despite its importance, there is limited literature available on the cytology of metastatic endometrial carcinoma in liquid-based cytology of bronchial brush (BB). In this article, we present two rare cases of lung metastasis from low-grade and early-stage EEC, along with a detailed analysis of the cytologic features observed in BB samples. These cases highlight the significance of cytological and histological pathology, complemented by immunohistochemistry (ICH) analysis, in the diagnosis and management of EEC patients. Pathologists should pay close attention to these aspects, while gynecologists need to be mindful of the follow-up and management of early-stage, low-grade EEC patients. By focusing on these areas, healthcare professionals can effectively contribute to the improved care and outcomes of patients with EEC.

Five-year disease-free survival in FIGO IA stage endometrial cancer patients: Tertiary institution experience in a developing country

Purpose

Endometrial cancer is characterized as histopathological, molecular, genetic, biological, and very diverse group of malignancies. Due to the need to precisely define the indications for adjuvant treatment in recent years, there has been a division made according to risk groups based on prognostic factors, which identify patients at risk for disease relapse, who may benefit from adjuvant therapy. The aim of this research was to examine the clinical and morphological factors that influence disease-free survival (DFS) and overall survival (OS) in patients with FIGO IA stage endometrial cancer.

Material and methods

A retrospective clinical study was conducted, primarily based on the identification of factors that influence five-year DFS and OS. The study integrated data of FIGO IA stage endometrial cancer patients, who presented to gynecological oncology board for the first time after operative treatment, from January 1, 2016 to January 1, 2022. Adjuvant radiotherapy was applied to patients with an initially higher risk of disease progression. Length of survival was analyzed using Kaplan-Meier method, while log-rank test was used to assess differences between groups.

Results

The results show that 5-year OS for 93 patients was 89.2% and DFS was 88.2%. Application of adjuvant brachytherapy, number of deliveries, MRI staging, type of institution where the surgery was performed influenced DFS. Pathohistological characteristics of tumor indicated a statistically significant impact on DFS.

Conclusions

Application of adjuvant brachytherapy in high-intermediate and high-risk patients contributes to DFS increase. Moreover, the existence of a pre-operative MRI assessment of the stage of disease as well as the type of healthcare provided by an institution where the surgery was performed, significantly affect DFS.

The Role of miRNAs in the Development, Proliferation, and Progression of Endometrial Cancer

Endometrial cancer is one of the most common cancers in developing and developed countries. Although the detection of this cancer is high at the early stages, there is still a lack of markers to monitor the disease, its recurrence, and metastasis. MiRNAs are in charge of the post-transcriptional regulation of genes responsible for the most important biological processes, which is why they are increasingly used as biomarkers in many types of cancer. Many studies have demonstrated the influence of miRNAs on the processes related to carcinogenesis. The characteristics of miRNA expression profiles in endometrial cancer will allow their use as diagnostic and prognostic biomarkers. This paper focuses on the discussion of selected miRNAs based on the literature and their role in the development of endometrial cancer.

CTNNB1 p.D32A (c.95A > C) somatic mutation in stage I grade 1 endometrioid endometrial carcinoma with lung metastasis: a case report

BACKGROUND

Most endometrial cancers are of low histological grade and uterine-confined, with a high 5-year survival rate. However, a small subset of women with low-grade and early-stage endometrioid endometrial cancer experience recurrence and death; thus, a more precise risk-stratification is needed.

CASE PRESENTATION

A 29-year-old woman presented with abnormal vaginal bleeding and was diagnosed with FIGO grade 1 endometrioid endometrial carcinoma by curettage. Comprehensive cancer staging including pelvic and para-aortic lymphadenectomy was then performed. Postoperative pathological findings suggested an FIGO grade 1 endometrioid endometrial carcinoma infiltrating the superficial muscle layer. The patient did not receive adjuvant therapy. After 4 years of follow-up, the patient returned to our institution with lung metastasis. She underwent thoracoscopic resection of the affected lobes, followed by six cycles of combined chemotherapy of paclitaxel and carboplatin. Next-generation sequencing showed that the primary and lung metastatic tumors shared 4 mutations: PTEN (p.P248Lfs*8), CTNNB1 (p.D32A), BCOR (p.N1425S) and CBL (p.S439N). Immunohistochemistry revealed nuclear location of β-catenin in the primary and lung metastatic tumor samples, indicating abnormal activation of β-catenin.

CONCLUSION

CTNNB1p.D32A (c.95A > C) mutation may be related to lung metastasis in this patient with low-grade early-stage endometrioid endometrial carcinoma.

Adjuvant radiation therapy in early-stage endometrial cancer with abnormal beta-catenin expression is associated with improved local control

OBJECTIVES

Emerging data suggests that abnormal (nuclear) β-catenin expression in some settings is associated with poorer outcomes. Our study aimed to verify the significance of abnormal β-catenin expression in early-stage endometrial cancer patients and determine if adjuvant radiation therapy (RT) improves local control.

METHODS

We identified 213 patients with FIGO 2018 stage I-II endometrioid endometrial cancer who underwent surgery from 2009 to 2021 with β-catenin expression assessed. Vaginal, regional, and distant recurrences were analyzed using competing risk methods, and overall survival was analyzed using Kaplan-Meier.

RESULTS

Median follow up was 53.2 months; 6.9% experienced vaginal, 8.2% regional, and 7.4% distant recurrence. For the entire cohort, abnormal β-catenin expression was significantly associated with vaginal recurrence and remained significant on multivariate analysis (p = 0.03). There were 114 patients in the no specific molecular profile (NSMP) subgroup, and abnormal β-catenin expression was present in 46.5%. In the NSMP subgroup, abnormal β-catenin expression was associated with increased rates of vaginal recurrence (p = 0.06). Abnormal β-catenin expression in the NSMP subgroup was significant on multivariate analysis for vaginal recurrence (p = 0.04). RT significantly decreased vaginal recurrences in the entire cohort in patients with abnormal β-catenin expression (0%) versus wild type expression (17.5%; p = 0.03). In the NSMP subgroup 0% of patients who received RT versus 20.9% of patients who did not receive RT experienced a vaginal recurrence (p = 0.03).

CONCLUSION

Use of adjuvant RT for stage I-II NSMP endometrial cancer with abnormal β-catenin expression improved local control. RT should be considered in these patients to decrease risk of vaginal recurrences.

Estrogen/Progesterone Receptor Loss, CTNNB1 and KRAS Mutations Are Associated With Local Recurrence or Distant Metastasis in Low-Grade Endometrial Endometrioid Carcinoma

A subset of endometrial endometrioid carcinomas (EECs) with low-grade histology recur with poor outcomes. Published evidence suggests that poor outcomes may be associated with loss of expression of ER-alpha (ER-α) as well as with β-Catenin-1 ( CTNNB1 ) and Kirsten rat sarcoma viral oncogene homolog ( KRAS ) mutations. This study reports on institutional experience with the incidence of recurrence in low-grade EEC and their association with CTNNB1 and KRAS mutations as well as estrogen/progesterone receptor (ER/PR) expression. Forty-eight (8.5%) out of 568 cases of low-grade EEC with biopsy-proven recurrence were identified; and were analyzed by immunohistochemistry for ER, PR, p53, MMR protein, and mutation analysis for exon 3 of the CTNNB1 and exon 2 of KRAS in relation to recurrence type, local or distant metastasis/recurrence. Twenty-three patients (4%) developed local, and 25 patients (4.4%) developed distant metastases/recurrence. Decreased expression or loss of ER/PR was found in 17/44 (38.6%) patients with recurrence. Eighty-four percent of patients with low-grade EEC and local recurrence had CTNNB1 mutations. Seventy-three percent of patients with distant metastasis/recurrence had KRAS mutations. The association of these mutations with the type of recurrence was statistically significant for both. Five cases with the morphology of low-grade EEC were reclassified as mesonephric-like carcinoma and were universally characterized by distant metastasis/recurrence, loss of ER/PR expression, large tumor size, absence of CTNNB1 mutations, and the presence of KRAS mutations. In low-grade EEC, CTNNB1 and KRAS mutations are associated with local recurrence and distant metastasis/recurrence, respectively, suggesting that these 2 different progression types may be conditioned by tumor genotype. ER/PR immunohistochemistry may be helpful in identifying poor performers in low-grade EEC. Furthermore, identification of the decreased expression or loss of ER/PR in tumors with low-grade histology should prompt consideration of mesonephric-like carcinoma, which is a more aggressive tumor than the low-grade EEC. KRAS mutations were associated with distant metastasis/recurrence in tumors with and without mesonephric-like phenotype.

Clinicopathologic Evaluation and Molecular Profiling of Recurrent Stage IA Endometrial Endometrioid Carcinoma: A Case-control Study

Most low-grade, early-stage endometrial endometrioid carcinomas (EEC) have an excellent prognosis; however, recurrences occur in a small subset with several studies reporting an increase in CTNNB1 exon 3 mutations in this population. Herein we evaluated 10 recurrent low-grade (FIGO 1 or 2), early-stage (FIGO IA) EECs matched to 10 nonrecurrent EECs to further characterize their clinicopathologic features and molecular phenotype. Cases were matched to controls based on size, grade, and depth of invasion. All tumors were evaluated for specific clinicopathologic parameters followed by next-generation sequencing using a 1213 gene panel. Recurrent EECs demonstrated no significant clinicopathologic differences when compared with nonrecurrent EECs, in terms of age, body mass index, pattern of invasion, presence of endometrial atypical hyperplasia/endometrioid intraepithelial neoplasia, associated metaplastic changes, peritumoral lymphocytes, mitoses, and tumor-infiltrating lymphocytes. Both cohorts also showed a similar number of pathogenic mutations, including CTNNB1 exon 3 mutations, as well as tumor mutational burden and microsatellite profiles. Although in this particular study, the lack of correlation between CTNNB1 exon 3 mutation and recurrence might be secondary to a small sample size, it also suggests the presence of other contributing factors. Thus, it helps set the foundation for larger series incorporating whole genome, transcriptome, proteome, and epigenome analyses to answer this clinically important question.

HE4 Tissue Expression as A Putative Prognostic Marker in Low-Risk/Low-Grade Endometrioid Endometrial Cancer: A Review

Low-grade stage I endometrioid endometrial carcinomas should have an excellent prognosis, but a small subset of these cancers can relapse. The search for putative immunohistochemical prognostic markers for relapse in low-risk/low-grade endometrioid endometrial cancers remains open. Among the candidate molecules that may implicate the roles of immunohistochemical risk markers, we focused our attention on human epididymis protein 4 (HE4) after a review of the literature. Few authors have devoted themselves to this topic, and none have found a correlation between the tissue expression of HE4 and the molecular classification of endometrial cancer. Five different variants of HE4 mRNA and multiple protein isoforms of HE4 were identified many years ago, but current HE4 assays only measure the total HE4 expression and do not distinguish the different proteins encoded by different mRNA variants. It is important to have an approach to distinguish specific variants in the future.

Construction of Endometrial Carcinoma ceRNA Network and Screening of Key Genes Based on TCGA Database

Objective

Long noncoding RNA (lncRNA) has received more and more attention in human tumor research. This study is aimed at clarifying the regulatory network of lncRNAs-microRNAs- (miRNAs-) mRNAs and at determining the relevant targets in the development of endometrial cancers.

Methods

Download the miRNA, mRNA, and lncRNA expression profile data of endometrial cancer patients from TCGA; use the "DESeq2" package of R software to identify the differential expression of miRNAs, mRNAs, and lncRNAs; construct a network of ceRNA; and perform gene ontology (GO) and Kyoto Encyclopedia of Gene and Genome (KEGG) pathway enrichment assessment on mRNAs in the network of ceRNA; string and Cytoscape 3.7.2 perform PPI assessment on target genes and TOP 10 hub gene screening; Cytoscape 3.7.2 computer program was employed for constructing the lncRNA-miRNA-TOP10 hub mRNA network diagram to determine the signal axis; StarBase database to verify the Top10 hub mRNA expression; the "survival" package in R computer program was implemented to analyze the survival rate of all genes on the lncRNA-miRNA-Top10 hub mRNA network diagram; RT-qPCR to verify the expression level of genes on the signal axis.

Results

1119 differential mRNAs, 14 differential lncRNAs, and 65 differential miRNAs were screened in TCGA; we constructed a ceRNA regulatory network composed of 5 DELs, 7 DEMs, and 90 DEGs; String combined with Cytoscape to screen out Top10 hub genes, namely: LEFTY1, LIN28A, LHX3, ST8SIA3, CEP55, FBXO32, DCN, ANGPTL1, ADRA1A, and KCNMA1; the StarBase database verification results show that ADRA1A, ANGPTL1, FBXO32, KCNMA1, and DCN are downregulated in endometrial cancer tissues; LEFTY1, LIN28A, LHX3, ST8SIA3, and CEP55 are upregulated in endometrial cancer; the constructed lncRNA-miRNA-hub Top10 mRNA network map identified CTD-2314B22, RP11-89 K21/hsa-miR-143, hsa-miR-424/LEFTY1, LIN28A, LHX3, ST8SIA3, and CEP55 signal axis; survival analysis results show that CTD-2314B22, RP11-89 K21, hsa-miR-96, hsa-miR-211, LHX3, ST8SIA3, and DCN are all related to survival; RT-qPCR results indicate CTD-2314B22, RP11-89 K21, LEFTY1, LIN28A, LHX3, ST8SIA3, and CEP55 are upregulated in endometrial cancer cells, and hsa-miR-143 and hsa-miR-424 are downregulated in endometrial cancer cells.

Conclusion

From the perspective of the lncRNA-miRNA-mRNA network, our study identified CTD-2314B22, RP11-89 K21/hsa-miR-143, hsa-miR-424/LEFTY1, LIN28A, LHX3, ST8SIA3, and CEP55 signal axis, which can present considerably potent biomarkers and therapeutic targets for treating endometrial cancer.

Estrogen Receptor- And Progesterone Receptor-Positive Thresholds in Predicting the Recurrence of Early Low-Risk Endometrial Cancer

Background

Estrogen receptors (ER) and progesterone receptors (PR) have important prognostic value in endometrial cancer, but there is no recognized positive immunohistochemical threshold for predicting the recurrence of early low-risk endometrial cancer. The purpose of this study was to clarify the optimal positive thresholds of the immunohistochemical parameters the ER and PR in early low-risk endometrial cancer.

Methods

A total of 332 patients with stage IA endometrial cancer were enrolled from the First Affiliated Hospital of Chongqing Medical University and People's Hospital of Sha ping ba District in Chongqing between January 2013 and December 2018. First, univariate and multivariate Cox regression analyses were used to analyze the correlation between various clinical factors and the prognosis of early low-risk endometrial cancer. Then, the receiver operating characteristic curve (ROC curve) and Youden index were used to determine the positive thresholds of ER and PR.

Results

The positive thresholds of ER and PR for predicting the recurrence of early low-risk endometrial cancer were 12% and 8%, respectively. Multivariate analysis showed that ER (P = 0.004), PR (P = 0.026), and p53 (P = 0.021) were risk factors for the prognosis of patients with early low-risk endometrial cancer. The recurrence-free survival and the overall survival in the low ER group and PR group were much lower than those in the high ER group and PR group (P < 0.001 of all).

Conclusions

ER and PR positive thresholds of 12% and 8%, respectively, are the most suitable for predicting the recurrence of early low-risk endometrial cancer.

Genomic Determinants of Early Recurrences in Low-Stage, Low-Grade Endometrioid Endometrial Carcinoma

Low-stage, low-grade endometrioid endometrial carcinoma (EEC), the most common histologic type of endometrial cancer, typically has a favorable prognosis. A subset of these cancers, however, displays an aggressive clinical course with early recurrences, including distant relapses. All statistical tests were 2-sided. Using a combination of whole-exome and targeted capture sequencing of 65 FIGO stage IA and IB grade 1 EECs treated with surgery alone, we demonstrate that chromosome 1q gain (odds ratio [OR] = 8.09, 95% confidence interval [CI] = 1.59 to 54.6; P = .02), PIK3CA mutation (OR = 9.16, 95% CI = 1.95 to 61.8; P = .01), and DNA mismatch repair-deficient molecular subtype (OR = 7.92, 95% CI = 1.44 to 87.6; P = .02) are independent predictors of early recurrences within 3 years in this patient population. Chromosome 1q gain was validated in an independent dataset of stage I grade 1 EECs subjected to whole-exome sequencing. Our findings expand on the repertoire of genomic parameters that should be considered in the evaluation of patients with low-stage, low-grade EEC.

Prognostic significance of CTNNB1 mutation in early stage endometrial carcinoma: a systematic review and meta-analysis

Background

In the last years, mutations in the exon 3 of CTNNB1 have emerged as a possible prognostic factor for recurrence in early stage endometrioid endometrial carcinoma, especially in cases with no specific molecular profile (NSMP).

Objective

To define the prognostic value of CTNNB1 mutations in early stage endometrioid endometrial carcinoma, through a systematic review and meta-analysis.

Methods

Electronic databases were searched from their inception to November 2020 for all studies assessing the prognostic value of CTNNB1 mutation in early stage (FIGO I–II) endometrioid endometrial carcinoma. Odds ratio (OR) for tumor recurrence and hazard ratio (HR) for disease-free survival (DFS) were calculated with a significant p value < 0.05.

Results

Seven studies with 1031 patients were included. Four studies were suitable for meta-analysis of OR and showed significant association between CTNNB1 mutation and the absolute number of recurrence (OR = 3.000; p = 0.019); the association became stronger after excluding patients with known molecular status other than NSMP (HR = 5.953; p = 0.012). Three studies were suitable for meta-analysis of HR and showed no significant association between CTNNB1 mutation and decreased DFS (HR = 1.847; p = 0.303); the association became significant after excluding patients with known molecular status other than NSMP (HR = 2.831; p = 0.026).

Conclusion

CTNNB1 mutation is significantly associated with recurrence in early stage endometrioid endometrial carcinomas, especially in the NSMP, appearing potentially useful in directing adjuvant treatment.

Prognostic Role of the Removed Vaginal Cuff and Its Correlation with L1CAM in Low-Risk Endometrial Adenocarcinoma

Objective: The aim of our study was to investigate the role of the excised vaginal cuff length as a prognostic factor in terms of DFS and recurrence rate/site, in low-risk endometrial cancer (EC) patients. Moreover, we correlated the recurrence with the expression of L1CAM. Material and Methods: From March 2001 to November 2016, a retrospective data collection was conducted of women undergoing surgical treatment for low-risk EC according to ESMO-ESGO-ESTRO consensus guidelines. Patients were divided into three groups according to their vaginal cuff length: V0 without vaginal cuff, V1 with a vaginal cuff shorter than 1.5 cm and V2 with a vaginal cuff longer than or equal to 1.5 cm. Results: 344 patients were included in the study: 100 in the V0 group, 179 in the V1 group and 65 in the V2 group. The total recurrence rate was 6.1%: the number of patients with recurrence was 8 (8%), 10 (5.6%) and 3 (4.6%), in the V0, V1 and V2 group, respectively. No statistically significant difference was found in the recurrence rate among the three groups. Although the DFS was higher in the V2 group, the result was not significant. L1CAM was positive in 71.4% of recurrences and in 82% of the distant recurrences. Conclusions: The rate of recurrence in patients with EC at low risk of recurrence does not decrease as the length of the vaginal cuff removed increases. Furthermore, the size of the removed vaginal cuff does not affect either the site of recurrence or the likelihood of survival.

Ultrastaging of 'negative' pelvic lymph nodes in patients with low- and intermediate-risk endometrioid endometrial cancer who developed non-vaginal recurrences

OBJECTIVE

Evidence on micrometastases and isolated tumor cells as factors associated with non-vaginal recurrence in low- and intermediate-risk endometrial cancer is limited. The goal of our study was to investigate risk factors for non-vaginal recurrence in low- and intermediate-risk endometrial cancer.

METHODS

Records of all patients with endometrial cancer surgically managed at the Mayo Clinic before sentinel lymph node implementation (1999-2008) were reviewed. We identified all patients with endometrioid low-risk (International Federation of Gynecology and Obstetrics (FIGO) stage I, grade 1 or 2 with myometrial invasion <50% and negative peritoneal cytology) or intermediate-risk (FIGO stage I, grade 1 or 2 with myometrial invasion ≥50% or grade 3 with myometrial invasion <50% and negative peritoneal cytology) endometrial cancer at definitive pathology after pelvic and para-aortic lymph node assessment. All pelvic lymph nodes of patients with non-vaginal recurrence (any recurrence excluding isolated vaginal cuff recurrences) underwent ultrastaging.

RESULTS

Among 1303 women, we identified 321 patients with low-risk (n=236) or intermediate-risk (n=85) endometrial cancer (median age 65.4 years; 266 (82.9%) stage IA; 55 (17.1%) stage IB). Of the total of 321, 13 patients developed non-vaginal recurrence (Kaplan-Meier rate 4.7% by 60 months; 95% CI 2.1% to 7.2%): 11 hematogenous/peritoneal and two para-aortic and distant lymphatic. Myometrial invasion and lymphovascular space invasion were univariately associated with non-vaginal recurrence. In these patients, the original hematoxylin/eosin slides review confirmed all 646 pelvic and para-aortic removed lymph nodes as negative. The ultrastaging of 463 pelvic lymph nodes did not identify any occult metastases (prevalence 0%; 95% CI 0% to 22.8% considering 13 patients; 95% CI 0% to 0.8% considering 463 pelvic lymph nodes).

CONCLUSION

There were no occult metastases in pelvic lymph nodes of patients with low- or intermediate-risk endometrial cancer with non-vaginal recurrence. Myometrial invasion and lymphovascular space invasion appear to be associated with non-vaginal recurrence.

Clinicopathological features and prognostic significance of CTNNB1 mutation in low-grade, early-stage endometrial endometrioid carcinoma

Low-grade and early-stage endometrioid endometrial carcinomas (EECs) have an overall good prognosis but biomarkers identifying patients at risk of relapse are still lacking. Recently, CTNNB1 exon 3 mutation has been identified as a potential risk factor of recurrence in these patients. We evaluate the prognostic value of CTNNB1 mutation in a single-centre cohort of 218 low-grade, early-stage EECs, and the correlation with beta-catenin and LEF1 immunohistochemistry as candidate surrogate markers. CTNNB1 exon 3 hotspot mutations were evaluated by Sanger sequencing. Immunohistochemical staining of mismatch repair proteins (MLH1, PMS2, MSH2, and MSH6), p53, beta-catenin, and LEF1 was performed in representative tissue microarrays. Tumours were also reviewed for mucinous and squamous differentiation, and MELF pattern. Nineteen (8.7%) tumours harboured a mutation in CTNNB1 exon 3. Nuclear beta-catenin and LEF1 were significantly associated with CTNNB1 mutation, showing nuclear beta-catenin a better specificity and positive predictive value for CTNNB1 mutation. Tumours with CTNNB1 exon 3 mutation were associated with reduced disease-free survival (p = 0.010), but no impact on overall survival was found (p = 0.807). The risk of relapse in tumours with CTNNB1 exon 3 mutation was independent of FIGO stage, tumour grade, mismatch repair protein expression, or the presence of lymphovascular space invasion. CTNNB1 exon 3 mutation has a negative impact on disease-free survival in low-grade, early-stage EECs. Nuclear beta-catenin shows a higher positive predictive value than LEF1 for CTNNB1 exon 3 mutation in these tumours.