p53abn Endometrial Cancer: understanding the most aggressive endometrial cancers in the era of molecular classification

Endometrial Carcinosarcomas are Almost Exclusively of p53abn Molecular Subtype After Exclusion of Mimics

SUMMARY

Our aim was to assess the molecular subtype(s) and perform a detailed morphologic review of tumors diagnosed as carcinosarcoma in a population-based cohort. Forty-one carcinosarcomas were identified from a cohort of 973 endometrial carcinomas diagnosed in 2016. We assessed immunostaining and sequencing data and undertook expert pathology reviews of these cases as well as all subsequently diagnosed (post-2016) carcinosarcomas of no specific molecular profile (NSMP) molecular subtype (n=3) from our institutions. In the 2016 cohort, 37 of the 41 carcinosarcomas (91.2%) were p53abn, 2 (4.9%) were NSMP, and 1 each (2.4%) were POLE mut and mismatch repair deficiency molecular subtypes, respectively. Of the 4 non-p53abn tumors on review, both NSMP tumors were corded and hyalinized (CHEC) pattern endometrioid carcinoma, the mismatch repair deficiency tumor was a grade 1 endometrioid carcinoma with reactive stromal proliferation, and the POLE mut tumor was grade 3 endometrioid carcinoma with spindle cell growth, that is, none were confirmed to be carcinosarcoma on review. We found 11 additional cases among the 37 p53abn tumors that were not confirmed to be carcinosarcoma on the review (3 undifferentiated or dedifferentiated carcinomas, 5 carcinomas with CHEC features, 2 carcinomas showing prominent reactive spindle cell stroma, and 1 adenosarcoma). In the review of institutional cases reported as NSMP carcinosarcoma after 2016, 3 were identified (1 adenosarcoma and 2 mesonephric-like adenocarcinoma on review). In this series, all confirmed endometrial carcinosarcomas were p53abn. The finding of any other molecular subtype in a carcinosarcoma warrants pathology review to exclude mimics.

Immunotherapy in MMR-d/MSI-H recurrent/metastatic endometrial cancer

INTRODUCTION

The advent of immunotherapy with immune checkpoint inhibitors (ICIs) has revolutionized the management of mismatch repair deficient (MMR-d)/microsatellite instability-high (MSI-H) endometrial cancer (EC). Initially investigated as monotherapy in phase I-II clinical trials for recurrent disease, immunotherapy demonstrated remarkable activity, yielding overall response rates (ORR) ranging from 27% to 58%. Based on these promising findings, phase III trials have explored the integration of immunotherapy into first-line treatment regimens for advanced/recurrent EC in combination with chemotherapy or other agents such as tyrosine kinase inhibitors (TKIs), resulting in improved ORR, progression-free survival, and overall survival compared to the standard chemotherapy regimen of paclitaxel and carboplatin. As a result, the incorporation of ICIs with standard platinum-based chemotherapy is becoming a new standard of care in MMR-d/MSI-H EC.

AREAS COVERED

This review synthesizes literature from PubMed, Embase databases, and recent congress abstracts on gynecological cancers. It covers MMR-d/MSI-H EC incidence, molecular diagnostics, clinical trial outcomes, predictive biomarkers for ICIs, patient profiles likely to benefit, resistance mechanisms, and the future of immunotherapy in this setting.

EXPERT OPINION

By offering a comprehensive overview, this review delineates the pivotal role of ICIs in the management of MMR-d/MSI-H EC.

Colombian consensus for the molecular diagnosis of endometrial cancer

Objective: The Cancer Genome Atlas research program (TCGA) developed the molecular classification for endometrial cancer with prognostic and therapeutic utility, which was replaced by the ProMisE (Proactive Molecular Risk Classifier for Endometrial Cancer) classification by consensus and international guidelines due to its high cost. This article aims to present national recommendations from an expert consensus that allows unification and implementation of the molecular classification for women with endometrial cancer nationwide, with a rational use of resources and technology. Methods: Consensus of 36 experts in clinical oncology, oncological gynecology, pathology, and genetics, with clinical practice in the national territory. The leader group performed a literature review and structuring of questions rated 1 to 9 points. A modified nominal group technique was used. There was a face-to-face meeting with master presentations, deliberative dialogue, and Google Forms (Google LLC, Mountain View, CA, USA) questionnaire voting with analysis and discussion of responses. The non-consensual responses led to a second round of voting. The final manuscript was finally prepared and revised. Results: Seven recommendations were formulated integrating the panelist responses based on evidence, but adjusted to the Colombian context and reality. Recommendation 1. The molecular classification is recommended in all the endometrial cancers using the immunohistochemistry markers as subrogated results from the molecular profile initially proposed in the TCGA classification. Recommendation 2. The sequential test strategy is recommended, starting with the immunohistochemistry markers (p53, MLH1, MSH 2, MSH6, PMS2) simultaneously in all the patients, defining to request POLE (DNA polymerase epsilon) (if available) according to the risk classification based on the surgical piece. Recommendation 3. It is recommended, that the gynecologist oncologist should be the one to request the POLE (if available) according to the final pathology report. This test must be requested for all endometrial cancers stage I-II, except in low risk (stage IA low grade endometrioid histology without linfovascular invasion normal p53) and, stages III-IV without residual disease, without affecting the request of subrogated immunohistochemistry molecular markers upon histology. The consensus proposes that the POLE is requested after the immunohistochemistry and according to the categories in the risk classification established by the 2020 ESGO/ESTRO/ESP guidelines. Recommendation 4. It is recommended to perform immunohistochemistry for hormonal receptors for all women with endometrial cancer and the HER2 in patients with p53abn, simultaneously with the others immunohistochemistry markers. Recommendation 5. It is recommended to perform the immunohistochemistry markers (p53, MLH1, MSH2, MSH6 y PMS2) in an initial endometrial biopsy or curettage when the specimen is adequate and available. In case the initial immunohistochemistry is inconclusive, or there are histological discrepancies between the initial and definitive pathology, it is recommended to repeat the molecular profile in the surgical pathology. The immunohistochemistry markers must be reported in the pathology report according to the CAP (College of American Pathologists) recommendations, independently of the type of sample. Recommendation 6. It is recommended to perform MLH1 promoter methylation testing in patients who exhibit loss of expression of MLH1 in immunohistochemistry whether it is accompanied or not with loss of expression of PMS2. All the patients with deficient MMR (mismatch repair), should be sent for genetic counseling to rule out Lynch syndrome. Recommendation 7. It is recommended to consider the molecular classification in addition to the classical histopathological criteria when making adjuvant judgments, as incorporated by the classification of prognostic groups of the 2020 ESGO/ESTRO/ESP guidelines. Conclusions: It is necessary to implement the molecular classification of endometrial cancer in clinical practice in accordance to the Colombian context, due to its prognostic and probably predictive value. This will enable the characterization of the Colombian population in order to offer individualized guided treatments. This is an academic and nonregulatory document.

circRNAs in Endometrial Cancer-A Promising Biomarker: State of the Art

Endometrial cancer (EC) is one of the most common malignant tumors among women in the 21st century, whose mortality rate is increasing every year. Currently, the diagnosis of EC is possible only after a biopsy. However, it is necessary to find a new biomarker that will help in both the diagnosis and treatment of EC in a non-invasive way. Circular RNAs (circRNAs) are small, covalently closed spherical and stable long non-coding RNAs (lncRNAs) molecules, which are abundant in both body fluids and human tissues and are expressed in various ways. Considering the new molecular classification of EC, many studies have appeared, describing new insights into the functions and mechanisms of circRNAs in EC. In this review article, we focused on the problem of EC and the molecular aspects of its division, as well as the biogenesis, functions, and diagnostic and clinical significance of circRNAs in EC.

Targeted and Shallow Whole-Genome Sequencing Identifies Therapeutic Opportunities in p53abn Endometrial Cancers

PURPOSE

Shallow whole-genome sequencing (sWGS) can detect copy-number (CN) aberrations. In high-grade serous ovarian cancer (HGSOC) sWGS identified CN signatures such as homologous recombination deficiency (HRD) to direct therapy. We applied sWGS with targeted sequencing to p53abn endometrial cancers to identify additional prognostic stratification and therapeutic opportunities.

EXPERIMENTAL DESIGN

sWGS and targeted panel sequencing was performed on formalin-fixed, paraffin-embedded p53abn endometrial cancers. CN alterations, mutational data and CN signatures were derived, and associations to clinicopathologic and outcomes data were assessed.

RESULTS

In 187 p53abn endometrial cancers, 5 distinct CN signatures were identified. Signature 5 was associated with BRCA1/2 CN loss with features similar to HGSOC HRD signature. Twenty-two percent of potential HRD cases were identified, 35 patients with signature 5, and 8 patients with BRCA1/2 somatic mutations. Signatures 3 and 4 were associated with a high ploidy state, and CCNE1, ERBB2, and MYC amplifications, with mutations in PIK3CA enriched in signature 3. We observed improved overall survival (OS) for patients with signature 2 and worse OS for signatures 1 and 3. Twenty-eight percent of patients had CCNE1 amplification and this subset was enriched with carcinosarcoma histotype. Thirty-four percent of patients, across all histotypes, had ERBB2 amplification and/or HER2 overexpression on IHC, which was associated with worse outcomes. Mutations in PPP2R1A (29%) and FBXW7 (16%) were among the top 5 most common mutations.

CONCLUSIONS

sWGS and targeted sequencing identified therapeutic opportunities in 75% of patients with p53abn endometrial cancer. Further research is needed to determine the efficacy of treatments targeting these identified pathways within p53abn endometrial cancers.

Potential of molecular classification to guide fertility-sparing management among young patients with endometrial cancer

The traditional histological classification system for endometrial carcinoma falls short in addressing the disease's molecular heterogeneity, prompting the need for alternative stratification methods. Proactive Molecular Risk Classifier for Endometrial Cancer (ProMisE) has emerged as a clinically efficient tool to categorize endometrial cancers according to mismatch repair deficiency, POLE exonuclease domain mutations, and p53 expression. However, the application of this classification to fertility-sparing treatments remains unexplored, and current guidelines lack specificity in how it should be used. In this review, we summarize the available literature and establish the framework for future investigations focused on molecular profiling-based risk assessment of endometrial cancer, with the goal of utilizing precision medicine to optimally counsel patients seeking fertility-sparing treatment. While the available evidence is limited and of low quality, it does provide insights and frames future perspectives for managing fertility-sparing approaches on the basis of molecular subtypes. Evidence suggests that mismatch repair-deficient tumors are likely to recur despite progestin therapy, emphasizing the need for alternative treatments, with targeted therapies being a new landscape that still needs to be explored. Tumors with POLE mutations exhibit a favorable prognosis, but the safety of hysteroscopic resection alone requires further investigation. p53 abnormal tumors have an unfavorable prognosis, raising questions about their suitability for fertility-sparing treatment. Lastly, the no specific molecular profile (or p53 wild-type) tumors, while having a relatively good prognosis, are heterogeneous and require more precise biomarkers to effectively guide therapy for those with poorer prognoses. Addressing these research gaps will lead to more precise guidelines to ensure optimal selection for fertility-sparing treatment.

Prognosis of isolated tumor cells and use of molecular classification in early stage endometrioid endometrial cancer

OBJECTIVE

We assessed the prognosis and molecular subtypes of early stage endometrioid endometrial cancer with isolated tumor cells within sentinel lymph nodes (SLNs) compared with node negative disease.

METHODS

Patients diagnosed with stage IA, IB, or II endometrioid endometrial cancer and primary surgical management were identified from January 1, 2007 to December 31, 2019. All SLNs underwent ultrastaging according to the institutional protocol. Patients with cytokeratin positive cells, micrometastases, and macrometastases were excluded. Clinical, pathology, and molecular subtype data were reviewed.

RESULTS

Overall, 1214 patients with early stage endometrioid endometrial cancer met the inclusion criteria, of whom 1089 (90%) had node negative disease and 125 (10%) had isolated tumor cells. Compared with node negative disease, the presence of isolated tumor cells had a greater association with deep myometrial invasion, lymphovascular space invasion, receipt of adjuvant therapy, and adjuvant chemotherapy with or without radiation (p<0.01). There was no significant difference in survival rates between patients with isolated tumor cells and node negative disease (3 year progression free survival rate 94% vs 91%, respectively, p=0.21; 3 year overall survival rate 98% vs 96%, respectively, p=0.45). Progression free survival did not significantly differ among patients with isolated tumor cells who received no adjuvant therapy or chemotherapy with or without radiation (p=0.31). There was no difference in the distribution of molecular subtypes between patients with isolated tumor cells (n=28) and node negative disease (n=194; p=0.26). Three year overall survival rates differed significantly when stratifying the entire cohort by molecular subtype (p=0.04).

CONCLUSIONS

Patients with isolated tumor cells demonstrated less favorable uterine pathologic features and received more adjuvant treatment with similar survival compared with patients with nodenegative disease. Among the available data, molecular classification did not have a significant association with the presence of isolated tumor cells, although copy number-high status was a poor prognostic indicator in early stage endometrioid endometrial cancer.

Molecular characterization as new driver in prognostic signatures and therapeutic strategies for endometrial cancer

Endometrial cancer (EC) incidence and mortality rates have been increasing, particularly among young females. Although more than 90% of ECs are sporadic, 5-10% are hereditary, a majority of which occurs within Hereditary Non-Polyposis Colorectal Cancer syndrome (HNPCC) or Lynch syndrome. The traditional histopathological classification differentiates EC between two main groups: type I (or endometrioid) and type II (including all other histopathological subtypes). However, this classification lacks reproducibility and does not account for the emerging molecular heterogeneity. In 2013, The Cancer Genome Atlas (TCGA) project proposed EC molecular classification defining four groups with different prognostic and predictive values and the current international guidelines are progressively establishing EC risk stratification and treatment based on both histopathological and molecular criteria. Our manuscript aims to summarize the current state of EC molecular characterizations, including germline alterations at the basis of hereditary EC predisposition, to discuss their clinical utility as prognostic and predictive markers.

Recurrence rates and patterns of recurrence in stage IA p53abn endometrial cancer with and without myometrial invasion

OBJECTIVES

Optimal management of patients with stage IA p53abn endometrial cancer without myoinvasion, classified as intermediate risk in the 2020 European Society of Gynaecological Oncology, European Society for Radiotherapy and Oncology, and European Society of Pathology (ESGO-ESTRO-ESP) guidelines, and the 2022 European Society of Medical Oncology (ESMO) guidelines, is currently unclear. Practice varies from surgery alone to adjuvant radiation±chemotherapy. Our aim was to assess the risk of disease recurrence in patients with stage IA p53abn endometrial cancer without myoinvasion compared with stage IA with myoinvasion (<50%).

METHODS

Stage IA p53abn endometrial cancers were identified from retrospective cohorts. Cases were segregated into stage IA with no myoinvasion, including (1) tumor restricted to a polyp, (2) residual endometrial tumor, and (3) no residual tumor in hysterectomy specimen, versus stage IA p53abn with myoinvasion (<50%), with treatment and outcomes assessed.

RESULTS

There were 65 stage IA p53abn endometrial cancers with no myoinvasion (22 polyp confined, 38 residual endometrial tumor, 2 no residual in hysterectomy specimen, 3 not specified) and 97 with myoinvasion. There was no difference in survival outcomes in patients with stage IA without myoinvasion (16% of patients recurred, 19% if there was residual endometrial disease) compared with stage IA with myoinvasion (17%). The risk of recurrence was lowest in patients with stage IA p53abn endometrial cancer without myoinvasion treated with chemotherapy±radiation (8%). Most recurrences in patients with stage IA without myoinvasion were distant (89%), with no isolated vaginal vault recurrences, and all except one distant recurrence occurred in patients who had not received adjuvant chemotherapy.

CONCLUSION

The recurrence rate in patients with stage IA p53abn endometrial cancer without myoinvasion was 16%, highest in the setting of residual endometrial disease (19%), and exceeding the threshold where adjuvant therapy is often considered. The high frequency of distant recurrences observed may support chemotherapy as part of the treatment regimen.

Analysis of patients with endometrial carcinoma using the ProMise classifier: a pilot study from India

BACKGROUND

Molecular subtyping of endometrial carcinomas (EC) has been shown to classify tumors into prognostically relevant groups. Characterizing EC with a limited number of markers viz., POLE mutations, p53 mutations, and MMR status, can provide valuable information.

DESIGN

Paraffin sections of a cohort of 48 EC from a tertiary care center were characterized for the above-mentioned molecular markers and analyzed in the context of survival.

METHODS

Formalin fixed paraffin embedded tissues from 48 EC were characterized for POLE mutations by Sanger sequencing (exons 9-14), for MMR (MLH1, MH2, MSH6) using immunohistochemistry (IHC) and copy number (high/low) using p53 IHC. Mutational status was integrated along with the clinicopathological details and survival analysis performed.

RESULTS

Eleven (22.9%) patients were MMR deficient, 3 (6.3%) had POLE mutation, while 2 (4.1%) had both POLE and P53 mutations (regarded as multiple classifiers). Twelve (25%) patients were found to have P53 mutations, while the remaining 20 (41.7%) had no specific molecular profile (NSMP). Median follow-up duration was 43.5 (2-62) months with 8 recurrences and 9 deaths. Tumors with POLE mutation had the most favorable prognosis followed by the NSMP and the MMR mutated group while the P53 and multiple classifier groups had the worst prognosis in terms of OS (Log-rank p: 0.006) and PFS (Log-rank p: 0.001).

CONCLUSION

The integration of molecular-clinicopathologic data for endometrial cancer classification, through cost-effective, clinically applicable assays appears to be a highly objective tool that can be adopted even in resource-limited settings. It has the potential to cause a shift in the paradigm of EC pathology and management practice.

Predictive and prognostic biomarkers in female genital tract tumours: an update highlighting their clinical relevance and practical issues

The evaluation of biomarkers by molecular techniques and immunohistochemistry has become increasingly relevant to the treatment of female genital tract tumours as a consequence of the greater availability of therapeutic options and updated disease classifications. For ovarian cancer, mutation testing for BRCA1/2 is the standard predictive biomarker for poly(ADP-ribose) polymerase inhibitor therapy, while homologous recombination deficiency testing may allow the identification of eligible patients among cases without demonstrable BRCA1/2 mutations. Clinical recommendations are available which specify how these predictive biomarkers should be applied. Mismatch repair (MMR) protein and folate receptor alpha immunohistochemistry may also be used to guide treatment in ovarian cancer. In endometrial cancer, MMR immunohistochemistry is the preferred test for predicting benefit from immune checkpoint inhibitor (ICI) therapy, but molecular testing for microsatellite instability may have a supplementary role. HER2 testing by immunohistochemistry and in situ hybridisation is applicable to endometrial serous carcinomas to assess trastuzumab eligibility. Immunohistochemistry for oestrogen receptor and progesterone receptor expression may be used for prognostication in endometrial cancer, but its predictive value for hormonal therapy is not yet proven. POLE mutation testing and p53 immunohistochemistry (as a surrogate for TP53 mutation status) serve as prognostic markers for favourable and adverse outcomes, respectively, in endometrial cancer, especially when combined with MMR testing for molecular subtype designation. For cervical cancer, programmed death ligand 1 immunohistochemistry may be used to predict benefit from ICI therapy although its predictive value is under debate. In vulvar cancer, p16 and p53 immunohistochemistry has established prognostic value, stratifying patients into three groups based on the human papillomavirus and TP53 mutation status of the tumour. Awareness of the variety and pitfalls of expression patterns for p16 and p53 in vulvar carcinomas is crucial for accurate designation. It is hoped that collaborative efforts in standardising and optimising biomarker testing for gynaecological tumours will contribute to evidence-based therapeutic decisions.

Molecular subtypes of endometrial cancer: Implications for adjuvant treatment strategies

BACKGROUND

When determining adjuvant treatment for endometrial cancer, the decision typically relies on factors such as cancer stage, histologic grade, subtype, and a few histopathologic markers. The Cancer Genome Atlas revealed molecular subtyping of endometrial cancer, which can provide more accurate prognostic information and guide personalized treatment plans.

OBJECTIVE

To summarize the expression and molecular basis of the main biomarkers of endometrial cancer.

SEARCH STRATEGY

PubMed was searched from January 2000 to March 2023.

SELECTION CRITERIA

Studies evaluating molecular subtypes of endometrial cancer and implications for adjuvant treatment strategies.

DATA COLLECTION AND ANALYSIS

Three authors independently performed a comprehensive literature search, collected and extracted data, and assessed the methodological quality of the included studies.

MAIN RESULTS

We summarized the molecular subtyping of endometrial cancer, including mismatch repair deficient, high microsatellite instability, polymerase epsilon (POLE) exonuclease domain mutated, TP53 gene mutation, and non-specific molecular spectrum. We also summarized planned and ongoing clinical trials and common therapy methods in endometrial cancer. POLE mutated endometrial cancer consistently exhibits favorable patient outcomes, regardless of adjuvant therapy. Genomic similarities between p53 abnormality endometrial cancer and high-grade serous ovarian cancer suggested possible overlapping treatment strategies. High levels of immune checkpoint molecules, such as programmed cell death 1 and programmed cell death 1 ligand 1 can counterbalance mismatch repair deficient endometrial cancer immune phenotype. Hormonal treatment is an appealing option for high-risk non-specific molecular spectrum endometrial cancers, which are typically endometrioid and hormone receptor positive. Combining clinical and pathologic characteristics to guide treatment decisions for patients, including concurrent radiochemotherapy, chemotherapy, inhibitor therapy, endocrine therapy, and immunotherapy, might improve the management of endometrial cancer and provide more effective treatment options for patients.

CONCLUSIONS

We have characterized the molecular subtypes of endometrial cancer and discuss their value in terms of a patient-tailored therapy in order to prevent significant under- or overtreatment.

Subclonal p53 immunostaining in the diagnosis of endometrial carcinoma molecular subtype

AIMS

The significance of subclonal expression of p53 (abrupt transition from wild-type to mutant-pattern staining) is not well understood, and the arbitrary diagnostic cut-off of 10% between NSMP and p53abn molecular subtypes of endometrial carcinoma (EC) has not been critically assessed. Our aim was to characterise subclonal p53 and discrepant p53 expression/TP53 sequencing results in EC and assess their clinical significance.

METHODS AND RESULTS

Subclonal p53 immuostaining on whole sections from 957 ECs was recorded. Agreement between TP53 mutational assessment and p53 immunostaining was evaluated. Subclonal p53 IHC staining was seen in 4.0% (38 of 957) of cases, with 23 of 957 (2.4%) showing mutant-pattern p53 staining in ≥10% of tumour cells. It was most commonly seen in POLEmut (nine of 65, 14%) and MMRd (13 of 274, 4.7%) EC ('multiple classifier' ECs), where subclonal p53 staining does not impact the molecular subtype diagnosis. Excluding POLEmut and MMRd EC, 11 of 957 (1.1%) showed ≥10% subclonal p53 from which four patients died of disease, while there were no deaths due to disease in the five patients with <10% mutant-pattern p53 staining. Agreement between p53 immunostaining and TP53 sequencing was 92.6%; most of the discrepant results were in the ultramutated POLEmut or hypermutated MMRd ECs. In NSMP and p53abn EC the agreement between IHC and sequencing was 95.8%.

CONCLUSIONS

Subclonal p53 staining ≥10% is present in only 1.1% of EC after excluding 'multiple classifier' ECs. The cut-off of ≥10% subclonal p53 staining identified patients at increased risk of dying from EC, supporting its use to diagnose p53abn molecular subtype.

Clinical Behavior and Molecular Landscape of Stage I p53-Abnormal Low-Grade Endometrioid Endometrial Carcinomas

PURPOSE

The clinical significance of the p53-abnormal (p53abn) molecular subtype in stage I low-grade endometrioid endometrial carcinoma (EEC) is debated. We aimed to review pathologic and molecular characteristics, and outcomes of stage I low-grade p53abn EEC in a large international cohort.

EXPERIMENTAL DESIGN

Previously diagnosed stage I p53abn EC (POLE-wild-type, mismatch repair-proficient) low-grade EEC from Canadian retrospective cohorts and PORTEC-1&2 trials were included. Pathology review was performed by six expert gynecologic pathologists blinded to p53 status. IHC profiling, next-generation sequencing, and shallow whole-genome sequencing was performed. Kaplan-Meier method was used for survival analysis.

RESULTS

We identified 55 stage I p53abn low-grade EEC among 3,387 cases (2.5%). On pathology review, 17 cases (31%) were not diagnosed as low-grade EEC by any pathologists, whereas 26 cases (47%) were diagnosed as low-grade EEC by at least three pathologists. The IHC and molecular profile of the latter cases were consistent with low-grade EEC morphology (ER/PR positivity, patchy p16 expression, PIK3CA and PTEN mutations) but they also showed features of p53abn EC (TP53 mutations, many copy-number alterations). These cases had a clinically relevant risk of disease recurrence (5-year recurrence-free survival 77%), with pelvic and/or distant recurrences observed in 12% of the patients.

CONCLUSIONS

A subset of p53abn EC is morphologically low-grade EEC and exhibit genomic instability. Even for stage I disease, p53abn low-grade EEC are at substantial risk of disease recurrence. These findings highlight the clinical relevance of universal p53-testing, even in low-grade EEC, to identify women at increased risk of recurrence.

Budget impact analysis of molecular subtype profiling in endometrial cancer

OBJECTIVE

This study evaluated the costs associated with four approaches to classifying endometrial cancer (EC), including histomorphological, histomorphological with ancillary immunohistochemical assays, histomolecular and selective molecular classification.

METHODS

Direct costs were determined per EC sample from the hospital's perspective. A budget impact analysis and sensitivity analysis were conducted to estimate the mean, minimum and maximum costs per sample and annual institutional costs in adjusted 2022 Canadian dollars. A provincial cost forecast was projected based on expected 2022 EC biopsies.

RESULTS

In 2018, our institution performed 190 EC biopsies. The mean cost per biopsy was $158 ($156-$212) for histomorphological classification, $384 ($360-$514) for histomorphological classification with immunohistochemistry and $1297 ($1265-1833) for histomolecular classification. Total annual institutional cost for histomorphological classification was $29,980 and $72,950 with immunohistochemistry. For histomolecular classification, the first year cost was $246,521, accounting for initial educational learning curve, and $233,461 thereafter, assuming a consistent number of biopsies per year. Targeted implementation of histomolecular classification among high-grade, p53 abnormal and/or MMR-deficient ECs (56% of cases) cost $169,688 in the first year and $162,418 annually thereafter. With a projected 3400 EC biopsies in Ontario in 2022, histomorphological classification would annually cost $537,078 and $1,305,677 with immunohistochemistry. Histomolecular classification would cost $4,410,203 in the first year and $4,176,737 annually once established. Selective molecular classification would lead to a cost of $3,044,178 in the first year and $2,913,443 thereafter.

CONCLUSIONS

The study highlights the need for informed decision-making when implementing molecular classification in clinical practice, given the substantial incremental healthcare costs associated with these approaches.

Targeted Molecular Testing in Endometrial Carcinoma: Validation of a Clinically Driven Selective ProMisE Testing Protocol

Incorporation of molecular classification into clinicopathologic assessment of endometrial carcinoma (EC) improves risk stratification. Four EC molecular subtypes, as identified by The Cancer Genome Atlas, can be diagnosed through a validated algorithm Pro active M olecular R is k Classifier for E ndometrial Cancer (ProMisE) using p53 and mismatch repair (MMR) protein immunohistochemistry (IHC), and DNA polymerase epsilon ( POLE) mutational testing. Cost and access are major barriers to universal testing, particularly POLE analysis. We assessed a selective ProMisE algorithm (ProMisE-S): p53 and MMR IHC on all EC's with POLE testing restricted to those with abnormal MMR or p53 IHC (to identify POLEmut EC with secondary abnormalities in MMR and/or p53) and those with high-grade or non-endometrioid morphology, stage >IA or presence of lymphovascular space invasion (so as to avoid testing on the lowest risk tumors). We retrospectively compared the known ProMisE molecular classification to ProMisE-S in 912 EC. We defined a group of "very low-risk" EC (G1/G2, endometrioid, MMR-proficient, p53 wild-type, stage IA, no lymphovascular space invasion) in whom POLE testing will not impact on patient care; using ProMisE-S, POLE testing would not be required in 55% of biopsies and 38% of all EC's, after evaluation of the hysterectomy specimen, in a population-based cohort. "Very low-risk" endometrioid EC with unknown POLE status showed excellent clinical outcomes. Fifteen of 166 (9%) of all p53abn EC showed G1/G2 endometrioid morphology, supporting the potential value of universal p53 IHC. The addition of molecular testing changed the risk category in 89/896 (10%) EC's. In routine practice, POLE testing could be further restricted to only those patients in whom this would alter adjuvant therapy recommendations.

Quantitative dynamic contrast-enhanced parameters and intravoxel incoherent motion facilitate the prediction of TP53 status and risk stratification of early-stage endometrial carcinoma

BACKGROUND

The aim of the study was to investigate the value of dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) and intravoxel incoherent motion (IVIM) in differentiating TP53-mutant from wild type, low-risk from non-low-risk early-stage endometrial carcinoma (EC).

PATIENTS AND METHODS

A total of 74 EC patients underwent pelvic MRI. Parameters volume transfer constant (K^trans), rate transfer constant (K_ep), the volume of extravascular extracellular space per unit volume of tissue (V_e), true diffusion coefficient (D), pseudo-diffusion coefficient (D*), and microvascular volume fraction (f) were compared. The combination of parameters was investigated by logistic regression and evaluated by bootstrap (1000 samples), receiver operating characteristic (ROC) curves, calibration curves, and decision curve analysis (DCA).

RESULTS

In the TP53-mutant group, K^trans and K_ep were higher and D was lower than in the TP53-wild group; K^trans, V_e, f, and D were lower in the non-low-risk group than in the low-risk group (all P < 0.05). In the identification of TP53-mutant and TP53-wild early-stage EC, K^trans and D were independent predictors, and the combination of them had an optimal diagnostic efficacy (AUC, 0.867; sensitivity, 92.00%; specificity, 80.95%), which was significantly better than D (Z = 2.169, P = 0.030) and K^trans (Z = 2.572, P = 0.010). In the identification of low-risk and non-low-risk early-stage EC, K^trans, V_e, and f were independent predictors, and the combination of them had an optimal diagnostic efficacy (AUC, 0.947; sensitivity, 83.33%; specificity, 93.18%), which was significantly better than D (Z = 3.113, P = 0.002), f (Z = 4.317, P < 0.001), K^trans (Z = 2.713, P = 0.007), and V_e (Z = 3.175, P = 0.002). The calibration curves showed that the above two combinations of independent predictors, both have good consistency, and DCA showed that these combinations were reliable clinical prediction tools.

CONCLUSIONS

Both DCE-MRI and IVIM facilitate the prediction of TP53 status and risk stratification in early-stage EC. Compare with each single parameter, the combination of independent predictors provided better predictive power and may serve as a superior imaging marker.

Molecular Profiling of Endometrial Cancer From TCGA to Clinical Practice

Molecular classification provides an objective, reproducible framework for categorization of endometrial cancers (ECs), informing prognosis and selection of therapy. Currently, the uptake of molecular classification, integration in to EC management algorithms, and enrollment in molecular subtype-specific clinical trials lags behind what it could be. Access to molecular testing is not uniform, and subsequent management (surgical, adjuvant therapy) is unacceptably variable. We are in the midst of a critical landscape change in this disease site, with increasing emphasis on the integration of molecular features in EC care that can potentially improve standard of care globally. This article summarizes the rationale for molecular classification of ECs, strategies for implementation in low and high resource settings, and actionable opportunities based on this information.

Grade and Estrogen Receptor Expression Identify a Subset of No Specific Molecular Profile Endometrial Carcinomas at a Very Low Risk of Disease-Specific Death

Endometrial carcinoma (EC) can be divided into 4 prognostic molecular subtypes, and no specific molecular profile (NSMP) type is the most commonly occurring type (∼50%). Although described as having an intermediate to favorable prognosis, this subtype encompasses pathologically and molecularly diverse tumors. We aimed to identify factors associated with outcomes within the NSMP ECs that might be used to stratify prognosis and direct treatment. Clinicopathologic, immunohistochemical, and genetic features of a large series of NSMP EC were used to identify parameters that could identify the subset associated with a very favorable outcome (disease-specific death rate <5% at 5 years, termed low-risk NSMP). A total of 1110 NSMP ECs were profiled. In a univariate analysis, stage, grade, lymphovascular invasion, estrogen receptor (ER) and progesterone receptor (PR) expression, L1CAM overexpression, and mutations in PIK3CA were associated with disease-specific survival. Two critical features, grade and ER expression, identified a low-risk NSMP subset (grade 1-2, ER-positive [>1%], 84% of cases), which showed a 5-year disease-specific death rate of 1.6% across all stages and 1.4% within stage I. The remaining cases (high-risk NSMPs, grade 3, and/or ER-negative status) were responsible for most of the disease-specific deaths (disease-specific death rate at 5 years, 22.9%; hazard ratio compared with that of low-risk NSMPs: 16.3; 95% CI, 8.4-31.7). Within NSMP EC, the low-risk and high-risk categories were of prognostic significance independent of the stage on a multivariate analysis. Low-grade and ER-positive NSMP ECs are a homogeneous low-risk group associated with an exceptionally favorable prognosis in which de-escalation and/or endocrine therapy strategies can be applied. Grade 3 and/or ER-negative status identifies a high-risk NSMP subset, including rare high-grade histotypes (eg, clear cell, dedifferentiated, and mesonephric-like), responsible for most NSMP-related deaths. Subclassification of NSMPs allows for the category of low-risk EC molecular subtypes to be dramatically expanded because it now includes both POLEmut and the much more common low-risk NSMP EC.

FANCD2 promotes the malignant behavior of endometrial cancer cells and its prognostic value

Defective DNA damage repair is a key mechanism affecting tumor susceptibility, treatment response, and survival outcome of endometrial cancer (EC). Fanconi anemia complementation group D2 (FANCD2) is the core component of the Fanconi anemia repair pathway. To explore the function of FANCD2 in EC, we examined the expression of FANCD2 in human specimens and databases, and discussed the possible mechanism of carcinogenesis by in vitro assays. Immunohistochemistry results showed overexpression of FANCD2 was detected in EC tissues compared to normal and atypical hyperplasia endometrium. Higher FANCD2 expression was correlated with deeper myometrial invasion (MI) and proficient mismatch repair status. The Cancer Genome Atlas (TCGA) database analysis showed FANCD2 was upregulated in EC compared with normal tissue. The high expression of FANCD2 was associated with poor overall survival in EC. Knockdown of FANCD2 expression in EC cell lines inhibited malignant proliferation and migration ability. We demonstrated that decreased FANCD2 expression results in increased DNA damage and decreased S-phase cells, leading to a decrease in proliferative capacity in EC cells. Down-regulated FANCD2 confers sensitivity of EC cells to interstrand crosslinking agents. This study provides evidence for the malignant progression and prognostic value of FANCD2 in EC.

Relevance of Molecular Profiling in Patients With Low-Grade Endometrial Cancer

IMPORTANCE

Patients with low-grade (ie, grade 1-2) endometrial cancer (EC) are characterized by their favorable prognosis compared with patients with high-grade (ie, grade 3) EC. With the implementation of molecular profiling, the prognostic relevance of tumor grading might lose attention. As most patients present with low-grade EC and have an excellent outcome, the value of molecular profiling for these patients is unclear.

OBJECTIVE

To determine the association of molecular profiling with outcomes among patients with low-grade EC.

DESIGN, SETTING, AND PARTICIPANTS

This retrospective cohort study included a multicenter international European cohort of patients diagnosed with EC between 1994 and 2018, with a median follow-up of 5.9 years. Molecular subgroups were determined by next-generation sequencing using single-molecule molecular inversion probes and by immunohistochemistry. Subsequently, tumors were classified as polymerase epsilon (POLE)-altered, microsatellite instable (MSI), tumor protein p53 (TP53)-altered, or no specific molecular profile (NSMP). Patients diagnosed with any histological subtypes and FIGO (International Federation of Gynecology and Obstetrics) stages of EC were included, but patients with early-stage EC (FIGO I-II) were only included if they had known lymph node status. Data were analyzed February 20 to June 16, 2022.

EXPOSURES

Molecular testing of the 4 molecular subgroups.

MAIN OUTCOMES AND MEASURES

The main outcome was disease-specific survival (DSS) within the molecular subgroups.

RESULTS

A total of 393 patients with EC were included, with a median (range) age of 64.0 (31.0-86.0) years and median (range) body mass index (BMI; calculated as weight in kilograms divided by height in meters squared) of 29.1 (18.0-58.3). Most patients presented with early-stage (290 patients [73.8%]) and low-grade (209 patients [53.2%]) disease. Of all patients, 33 (8.4%) had POLE-altered EC, 78 (19.8%) had MSI EC, 72 (18.3%) had TP53-altered EC, and 210 (53.4%) had NSMP EC. Across all molecular subgroups, patients with low-grade EC had superior 5-year DSS compared with those with high-grade EC, varying between 90% to 100% vs 41% to 90% (P < .001). Multivariable analysis in the entire cohort including age, tumor grade, FIGO stage, lymphovascular space invasion, and the molecular subgroups as covariates found that only high-grade (hazard ratio [HR], 4.29; 95% CI, 2.15-8.53; P < .001), TP53-altered (HR, 1.76; 95% CI, 1.04-2.95; P = .03), and FIGO stage III or IV (HR, 4.26; 95% CI, 2.50-7.26; P < .001) disease were independently associated with reduced DSS.

CONCLUSIONS AND RELEVANCE

This cohort study found that patients with low-grade EC had an excellent prognosis independent of molecular subgroup. These findings do not support routine molecular profiling in patients with low-grade EC, and they demonstrate the importance of primary diagnostic tumor grading and selective profiling in low-grade EC to increase cost-effectiveness.

Association of immunohistochemical profiles with histotypes in endometrial carcinomas

OBJECTIVE

Although a large number of endometrial cancer patients are cured with surgery alone, there are significant numbers of patients with more aggressive variants of endometrial carcinoma for whom the prognosis remains poor. We investigated the effects of prevalence, histotypes, and immunohistochemical profiles on prognostic value in a hospital-based population.

MATERIALS AND METHODS

A retrospective study of surgically resected primary endometrial carcinoma was included. Immunohistochemical stains were performed on formalin-fixed paraffin-embedded tissue microarray sections for β-Catenin, estrogen receptor (ER), progesterone receptor (PR), HER-2, MLH1, MSH2, MSH6, PMS2, and p53.

RESULTS

Loss of mismatch repair expression was detected in 25.4% of samples (29/114, mean age 57 years) of the tumors. The following loss of expression was observed in patients: MLH1/PMS2 in 16.6% of patients, MSH6 in 7.0% of patients, MLH1 in 0.9% of patients, and MSH6/PMS2/MLH1 in 0.9% of patients. Immunohistochemistry of p53 was analyzed for 111 patients. A total of 13 patients (11.7%, mean age 64 years) had p53-abnormal expression (absent, cytoplasmic or diffuse strong positive patterns), and more than half (9/13, 69.2%) had endometrioid histotype. Abnormalities in p53 were significantly associated with histotype (p = 0.001), advanced tumor stage (p = 0.038), death of disease (p = 0.002), PR percentage (p = 0.002), and HER-2 expression (p = 0.018). Immunohistochemical nuclear localization of β-Catenin was detected in 7.1% of the cohort. The combination of p53 and nuclear β-Catenin expressions was not significantly predictive of disease-free or overall survival.

CONCLUSION

The results of this study are useful for management of endometrial cancer in patients with DNA mismatch repair, abnormal p53 expression, or nuclear localization of β-Catenin.

A novel algorithm to implement the molecular classification according to the new ESGO/ESTRO/ESP 2020 guidelines for endometrial cancer

OBJECTIVE

To compare the risk class attribution with molecular classification unknown to those with molecular classification known, according to the European Society of Gynaecological Oncology/European Society for Radiotherapy and Oncology/European Society of Pathology (ESGO/ESTRO/ESP) 2020 guidelines on endometrial cancer, with a focus on risk group migration. Additionally, to evaluate the capability of a novel molecular analysis algorithm to reduce the number of required tests.

METHODS

We conducted a retrospective study including all consecutive patients with endometrial cancer undergoing surgery and comprehensive molecular analyses between April 2019 and December 2021. Molecular analyses including immunohistochemistry for p53 and mismatch repair (MMR) proteins, and DNA sequencing for POLE exonuclease domain were performed to classify tumors as POLE-mutated (POLE), MMR-deficient (MMR-d), p53 abnormal (p53abn), or non-specific molecular profile (NSMP). The two risk classifications of the ESGO/ESTRO/ESP 2020 guidelines were compared to estimate the proportion of patients in which the molecular analysis was able to change the risk class attribution. We developed a novel algorithm where the molecular analyses are reserved only for patients in whom incorporation of the molecular classification could change the risk class attribution.

RESULTS

A total of 278 patients were included. Molecular analyses were successful for all cases, identifying the four subgroups: 27 (9.7%) POLE, 77 (27.7%) MMR-d, 49 (17.6%) p53abn, and 125 (45.0%) NSMP. Comparison of risk class attribution between the two classification systems demonstrated discordance in the risk class assignment in 19 (6.8%, 95% CI 4.2% to 10.5%) cases. The application of our novel algorithm would have led to a reduction in the number of POLE sequencing tests by 67% (95% CI 61% to 73%) and a decrease of p53 immunohistochemistry by 27% (95% CI 22% to 33%), as compared with the application of molecular classification to all patients.

CONCLUSION

Molecular categorization of endometrial cancer allows the reallocation of a considerable proportion of patients in a different risk class. Furthermore, the application of our algorithm enables a reduction in the number of required tests without affecting the risk classification.

The immunohistochemical molecular risk classification in endometrial cancer: A pragmatic and high-reproducibility method

INTRODUCTION

The aim of this study is to assess the clinical reproducibility and the potential oncological validity of the molecular information provided by the immunohistochemistry (IHC) to properly stratify the endometrial cancer patients.

METHODS

Retrospective IHC analyses were conducted in a large series of 778 pre-operative uterine-confined ECs, studying the presence/absence of MLH1, MSH2, MSH6 and PMS2 to define the mismatch repair (MMR) stable or instable phenotype; the presence of p53 mutations and other molecular features. The molecular profile was correlated with histological, clinical and prognostic data.

RESULTS

Based on IHC assessment, we defined 3 EC populations: stable MMR patients (MMRs), instable patients (MMRi) and p53 mutated patients (p53+). Our result demonstrated that the IHC stratification statistically correlated with the most relevant pathologic-clinical features: FIGO stage (p < 0.001), grading (p < 0.001), histotype (p < 0.001), presence of LVSI (p < 0.001), myometrial invasion and tumor dimension (p = 0.003 for both). These 3 IHC populations statistically reflected the EC risk class ESGO-ESMO-ESP classification 2021 (p < 0.001). These results were also confirmed in the Kaplan-Meier curves in terms of overall survival (OS) and disease-free survival (DFS) (p < 0.0001). The multivariate analyses demonstrated that absence of estrogen receptor (ER) impacted the OS (p = 0.011) and, the Age > 60 years and the ER-status the DFS (p = 0.041 and p = 0.004).

CONCLUSION

In this large series, we demonstrated that the pragmatic and systematic use of IHC may have an important role to properly stratify, in terms of histological features and clinical outcomes, the EC patients.

Variation in practice in endometrial cancer and potential for improved care and equity through molecular classification

OBJECTIVES

We measured the variation in practice across all aspects of endometrial cancer (EC) management and assessed the potential impact of implementation of molecular classification.

METHODS

Centers from across Canada provided representative tumor samples and clinical data, including preoperative workup, operative management, hereditary cancer program (HCP) referrals, adjuvant therapy, surveillance and outcomes, for all EC patients diagnosed in 2016. Tumors were classified into the four ProMisE molecular subtypes.

RESULTS

A total of 1336 fully evaluable EC patients were identified from 10 tertiary cancer centers (TC; n = 1022) and 19 community centers (CC; n = 314). Variation of surgical practice across TCs was profound (14-100%) for lymphadenectomy (LND) (mean 57% Gr1/2, 82% Gr3) and omental sampling (20% Gr1/2, 79% Gr3). Preoperative CT scans were inconsistently obtained (mean 32% Gr1/2, 51% Gr3) and use of adjuvant chemo or chemoRT in high risk EC ranged from 0-55% and 64-100%, respectively. Molecular subtyping was performed retrospectively and identified 6% POLEmut, 28% MMRd, 48% NSMP and 18% p53abn ECs, and was significantly associated with survival. Within patients retrospectively diagnosed with MMRd EC only 22% had been referred to HCP. Of patients with p53abn EC, LND and omental sampling was not performed in 21% and 23% respectively, and 41% received no chemotherapy. Comparison of management in 2016 with current 2020 ESGO/ESTRO/ESP guidelines identified at least 26 and 95 patients that would have been directed to less or more adjuvant therapy, respectively (10% of cohort).

CONCLUSION

Molecular classification has the potential to mitigate the profound variation in practice demonstrated in current EC care, enabling reproducible risk assessment, guiding treatment and reducing health care disparities.

Endometrial Cancer: Transitioning from Histology to Genomics

Endometrial carcinoma (EC) is traditionally treated with surgery and adjuvant treatment depending on clinicopathological risk factors. The genomic analysis of EC in 2013 and subsequent studies using immunohistochemistry have led to the current EC molecular classification into: polymerase epsilon mutated (POLEmut), p53 abnormal (p53abn), mismatch repair deficient (MMRd), and no specific molecular profile (NSMP). The four groups have prognostic value and represent a promising tool for clinical decision-making regarding adjuvant treatment. Molecular classification was integrated into the recent European Society of Gynecologic Oncology (ESGO) management guidelines. POLEmut EC has favorable outcomes and retrospective studies found that omitting adjuvant treatment is safe in this group; two prospective clinical trials, PORTEC-4 and TAPER, are ongoing to assess this. p53 abn is associated with increased recurrence, decreased survival, and benefitted from chemotherapy in the PORTEC-3 subgroup molecular analysis. The clinical trials PORTEC-4a and CANSTAMP will prospectively assess this. MMRd and NSMP groups have intermediate prognosis and will likely continue to rely closely on clinicopathological features for adjuvant treatment decisions. In addition, the molecular classification has led to exploring novel treatments such as checkpoint inhibitors. Overall, the molecular perspective on EC and associated clinical trials will likely refine EC risk stratification to optimize care and avoid overtreatment.

Key changes to the world health organisation (who) classification of female genital tumours introduced in the 5TH edition (2020)

An updated World Health Organisation (WHO) Classification of Female Genital Tumours was published in Autumn 2020. We discuss the major new additions and changes from the prior 2014 Classification with discussion of the reasons underlying these. A feature of the new Classification is the greater emphasis on key molecular events with integration of morphological and-molecular features. Most of the major changes from the prior Classification pertain to uterine (corpus and cervix) and vulval tumours but changes in all organs are covered.

Selection of endometrial carcinomas for p53 immunohistochemistry based on nuclear features

The World Health Organization endorses molecular subclassification of endometrial endometrioid carcinomas (EECs). Our objectives were to test the sensitivity of tumor morphology in capturing p53 abnormal (p53abn) cases and to model the impact of p53abn on changes to ESGO/ESTRO/ESP (European Society of Gynaecological Oncology/European Society for Radiotherapy and Oncology/European Society of Pathology) risk stratification. A total of 292 consecutive endometrial carcinoma resections received at Foothills Medical Centre, Calgary, Canada (2019–2021) were retrieved and assigned to ESGO risk groups with and without p53 status. Three pathologists reviewed the representative H&E‐stained slides, predicted the p53 status, and indicated whether p53 immunohistochemistry (IHC) would be ordered. Population‐based survival for endometrial carcinomas diagnosed during 2008–2016 in Alberta was obtained from the Alberta Cancer Registry. The cohort consisted mostly of grade 1/2 endometrioid carcinomas (EEC1/2; N = 218, 74.6%). One hundred and fifty‐two EEC1/2 (52.1% overall) were stage IA and 147 (50.3%) were low risk by ESGO. The overall prevalence of p53abn and subclonal p53 was 14.5 and 8.3%, respectively. The average sensitivity of predicting p53abn among observers was 83.6%. Observers requested p53 IHC for 39.4% with 98.5% sensitivity to detect p53abn (99.6% negative predictive value). Nuclear features including smudged chromatin, pleomorphism, atypical mitoses, and tumor giant cells accurately predicted p53abn. In 7/292 (2.4%), p53abn upgraded ESGO risk groups (2 to intermediate risk, 5 to high risk). EEC1/2/stage IA patients had an excellent disease‐specific 5‐year survival of 98.5%. Pathologists can select cases for p53 testing with high sensitivity and low risk of false negativity. Molecular characterization of endometrial carcinomas has great potential to refine ESGO risk classification for a small subset but offers little value for approximately half of endometrial carcinomas, namely, EEC1/2/stage IA cases.

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.

The emerging role of molecular pathology in directing the systemic treatment of endometrial cancer

Following the discovery of the four molecular subtypes of endometrial cancer (EC) by The Cancer Genome Atlas (TCGA) in 2013, subsequent studies used surrogate markers to develop and validate a clinically relevant EC classification tool to recapitulate TCGA subtypes. Molecular classification combines focused sequencing (POLE) and immunohistochemistry (mismatch repair and p53 proteins) to assign patients with EC to one of four molecular subtypes: POLEmut, MMRd, p53abn and NSMP (no specific molecular profile). Unlike histopathological evaluation, the molecular subtyping of EC offers an objective and reproducible classification system that has been shown to have prognostic value and therapeutic implications. It is an exciting time in EC care where we have moved beyond treatment based on histomorphology alone, and molecular classification will now finally allow assessment of treatment efficacy within biologically similar tumours. It is now recommended that molecular classification should be considered for all ECs, and should be performed routinely in all high grade tumours. It is also recommended to incorporate molecular classification into standard pathology reporting and treatment decision-making algorithms. In this review, we will discuss how the molecular classification of EC can be used to guide both conventional and targeted therapy in this new molecular era.