Endometriosis-associated Ovarian Carcinomas Research Articles

Genomic alterations in ovarian endometriosis and subsequently diagnosed ovarian carcinoma.

Can the alleged association between ovarian endometriosis and ovarian carcinoma be substantiated by genetic analysis of endometriosis diagnosed prior to the onset of the carcinoma? The data suggest that ovarian carcinoma does not originate from ovarian endometriosis with a cancer-like genetic profile; however, a common precursor is probable. Endometriosis has been implicated as a precursor of ovarian carcinoma based on epidemiologic studies and the discovery of common driver mutations in synchronous disease at the time of surgery. Endometrioid ovarian carcinoma and clear cell ovarian carcinoma are the most common endometriosis-associated ovarian carcinomas (EAOCs). The pathology biobanks of two university hospitals in Sweden were scrutinized to identify women with surgically removed endometrioma who subsequently developed ovarian carcinoma (1998-2016). Only 45 archival cases with EAOC and previous endometriosis were identified and after a careful pathology review, 25 cases were excluded due to reclassification into non-EAOC (n = 9) or because ovarian endometriosis could not be confirmed (n = 16). Further cases were excluded due to insufficient endometriosis tissue or poor DNA quality in either the endometriosis, carcinoma, or normal tissue (n = 9). Finally 11 cases had satisfactory DNA from all three locations and were eligible for further analysis. Epithelial cells were collected from formalin-fixed and paraffin-embedded (FFPE) sections by laser capture microdissection (endometrioma n = 11) or macrodissection (carcinoma n = 11) and DNA was extracted. Normal tissue from FFPE sections (n = 5) or blood samples collected at cancer diagnosis (n = 6) were used as the germline controls for each included patient. Whole-exome sequencing was performed (n = 33 samples). Somatic variants (single-nucleotide variants, indels, and copy number alterations) were characterized, and mutational signatures and kataegis were assessed. Microsatellite instability and mismatch repair status were confirmed with PCR and immunohistochemistry, respectively. The median age for endometriosis surgery was 42 years, and 54 years for the subsequent ovarian carcinoma diagnosis. The median time between the endometriosis and ovarian carcinoma was 10 (7-30) years. The data showed that all paired samples harbored one or more shared somatic mutations. Non-silent mutations in cancer-associated genes were frequent in endometriosis; however, the same mutations were never observed in subsequent carcinomas. The degree of clonal dominance, demonstrated by variant allele frequency, showed a positive correlation with the time to cancer diagnosis (Spearman's rho 0.853, P < 0.001). Mutations in genes associated with immune escape were the most conserved between paired samples, and regions harboring these genes were frequently affected by copy number alterations in both sample types. Mutational burdens and mutation signatures suggested faulty DNA repair mechanisms in all cases. Datasets are available in the supplementary tables. Even though we located several thousands of surgically removed endometriomas between 1998 and 2016, only 45 paired samples were identified and even fewer, 11 cases, were eligible for sequencing. The observed high level of intra- and inter-heterogeneity in both groups (endometrioma and carcinoma) argues for further studies of the alleged genetic association. The observation of shared somatic mutations in all paired samples supports a common cellular origin for ovarian endometriosis and ovarian carcinoma. However, contradicting previous conclusions, our data suggest that cancer-associated mutations in endometriosis years prior to the carcinoma were not directly associated with the malignant transformation. Rather, a resilient ovarian endometriosis may delay tumorigenesis. Furthermore, the data indicate that genetic alterations affecting the immune response are early and significant events. The present work has been funded by the Sjöberg Foundation (2021-01145 to K.S.; 2022-01-11:4 to A.S.), Swedish state under the agreement between the Swedish government and the county councils, the ALF-agreement (965552 to K.S.; 40615 to I.H.; 965065 to A.S.), Swedish Cancer Society (21-1848 to K.S.; 21-1684 to I.H.; 22-2080 to A.S.), BioCARE-A Strategic Research Area at Lund University (I.H. and S.W.-F.), Mrs Berta Kamprad's Cancer Foundation (FBKS-2019-28, I.H.), Cancer and Allergy Foundation (10381, I.H.), Region Västra Götaland (A.S.), Sweden's Innovation Agency (2020-04141, A.S.), Swedish Research Council (2021-01008, A.S.), Roche in collaboration with the Swedish Society of Gynecological Oncology (S.W.-F.), Assar Gabrielsson Foundation (FB19-86, C.M.), and the Lena Wäpplings Foundation (C.M.). A.S. declares stock ownership and is also a board member in Tulebovaasta, SiMSen Diagnostics, and Iscaff Pharma. A.S. has also received travel support from EMBL, Precision Medicine Forum, SLAS, and bioMCC. The remaining authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.

Differential Expression of Long Non-coding Ribonucleic Acid (RNA) Genes in Endometriosis-associated Ovarian Cancer (EAOC): A Pilot Meta-analysis for Pathological Insights and Potential Diagnostic Biomarker Identification

Introduction: Endometrioid and clear cell carcinomas of the ovary are the most common subtypes of epithelial malignancy arising from endometriosis and are often termed endometriosis-associated ovarian carcinomas (EAOCs). There is a paucity of experimental evidence in the medical literature regarding the role of long non-coding ribonucleic acid (RNA) gene expression in the pathogenesis of these carcinomas. Purpose: There is a need to develop understanding of the pathogenesis of these carcinomas for neoplastic risk stratification in endometriosis and to develop novel diagnostic biomarkers. Clear cell carcinoma of the ovary, in particular, has a poor prognosis as a result of resistance to standard platinum-based chemotherapy. Methods: RNAseq datasets from EAOCs were downloaded from Gene Expression Omnibus (GEO) and compared with normal ovarian control sequences using a customized bioinformatic pipeline. Results: We found 88 differentially expressed non-coding RNA molecules present in both endometrioid and clear cell carcinoma types compared with controls. A further 117 were specifically differentially expressed in the endometrioid carcinoma group and 128 in clear cell carcinoma samples alone. Genes of interest for further study from the 88 shared set in both EAOC types include CASC9, RP4-561L24.3, SLC2A1-AS1, LUCAT1, XIST, CASC15, and MIR99AHG. These genes appear to influence ferroptosis as a common pathway. Conclusions: Alterations in the ferroptosis pathway may be a key event in development of EAOC in ovarian endometriosis patients. Further work is required to elucidate the function of the candidate RNA genes identified in this study by in-vitro, cell line and cultured organoid experiments. These candidate RNA gene biomarkers have potential clinical utility in early diagnosis, risk stratification of endometriosis, and post-surgical monitoring.

TCGA molecular classification in endometriosis-associated ovarian carcinomas: Novel data on clear cell carcinoma

BackgroundClear cell and endometrioid ovarian carcinomas (OCC and OEC, respectively) have a presumed origin in endometriosis and share molecular alterations with each other and with their endometrial counterparts. The Cancer Genome Atlas (TCGA)-based molecular classification stratifies endometrial carcinomas into four categories: POLE mutated (POLEmut), mismatch repair deficient (MMRd), p53 abnormal (p53abn) and no specific molecular profile (NSMP) with divergent prognoses. The subsequent studies are indicative that this TCGA classification has some value in OEC, but the knowledge related to OCC is limited. MethodsEndometrial carcinoma molecular classification was evaluated and compared in a large series of OCCs (n = 115) and OECs (n = 158). POLE mutation analysis and tissue microarray-based immunohistochemistry for mismatch repair and p53 proteins were performed. ResultsThe distribution to the molecular groups was as follows: POLEmut 0.9%/3.2%, MMRd 3.5%/6.3%, p53abn 20%/30%, and NSMP 76%/60% in OCCs/OECs, respectively. The proportion of NSMP tumors was the largest in both histological types and significantly higher in OCC than OEC (p = 0.009). The molecular classification correlated significantly with DSS in both OCCs and OECs (p < 0.001 and p = 0.009, respectively), and with DFS in OCCs (p = 0.001). POLEmut and MMRd OCCs carried excellent prognosis, whereas MMRd OECs presented with poorer outcome. The p53abn group was associated with the poorest prognosis in both tumor types, particularly emphasized in OCCs. ConclusionsTCGA molecular classification associated with patient outcome in both histotypes, and the difference in prognosis between the molecular groups was even more marked in OCC. The large amount of NSMP tumors highlights the need for further studies.

Validated biomarker assays confirm that ARID1A loss is confounded with MMR deficiency, CD8+ TIL infiltration, and provides no independent prognostic value in endometriosis-associated ovarian carcinomas.

ARID1A (BAF250a) is a component of the SWI/SNF chromatin modifying complex, plays an important tumour suppressor role, and is considered prognostic in several malignancies. However, in ovarian carcinomas there are contradictory reports on its relationship to outcome, immune response, and correlation with clinicopathological features. We assembled a series of 1623 endometriosis-associated ovarian carcinomas, including 1078 endometrioid (ENOC) and 545 clear cell (CCOC) ovarian carcinomas, through combining resources of the Ovarian Tumor Tissue Analysis (OTTA) Consortium, the Canadian Ovarian Unified Experimental Resource (COEUR), local, and collaborative networks. Validated immunohistochemical surrogate assays for ARID1A mutations were applied to all samples. We investigated associations between ARID1A loss/mutation, clinical features, outcome, CD8+ tumour-infiltrating lymphocytes (CD8+ TILs), and DNA mismatch repair deficiency (MMRd). ARID1A loss was observed in 42% of CCOCs and 25% of ENOCs. We found no associations between ARID1A loss and outcomes, stage, age, or CD8+ TIL status in CCOC. Similarly, we found no association with outcome or stage in endometrioid cases. In ENOC, ARID1A loss was more prevalent in younger patients (p = 0.012) and was associated with MMRd (p < 0.001) and the presence of CD8+ TILs (p = 0.008). Consistent with MMRd being causative of ARID1A mutations, in a subset of ENOCs we also observed an association with ARID1A loss-of-function mutation as a result of small indels (p = 0.035, versus single nucleotide variants). In ENOC, the association with ARID1A loss, CD8+ TILs, and age appears confounded by MMRd status. Although this observation does not explicitly rule out a role for ARID1A influence on CD8+ TIL infiltration in ENOC, given current knowledge regarding MMRd, it seems more likely that effects are dominated by the hypermutation phenotype. This large dataset with consistently applied biomarker assessment now provides a benchmark for the prevalence of ARID1A loss-of-function mutations in endometriosis-associated ovarian cancers and brings clarity to the prognostic significance. © 2021 The Pathological Society of Great Britain and Ireland.

The rhesus macaque: a unique and compelling model for human endometriosis-associated ovarian carcinomas

Objectives: Clear cell ovarian carcinoma and endometrioid ovarian carcinoma (EnOC) are considered endometriosis-associated ovarian cancers (EAOCs). Given no higher order animal model currently exists for these cancers, we propose a novel animal model, the rhesus macaque (Macaca mulatta), for better understanding malignant transformation from endometriosis to EAOCs. Methods: The Wisconsin National Primate Research Center (WNPRC) maintains a multigenerational colony of Indian-derived rhesus macaques with well-documented incidence of spontaneous endometriosis. WNPRC researchers developed a model in which estrogen receptor-a was knocked down in the hypothalamus (hypoER-a) of adult rhesus females. Standard hemotoxylin and eosin (HE) and progesterone receptor (PR). Results: Twelve animals were evaluated, 6 hypoER-a and 6 control. Age at necropsy and characteristics associated with rhesus endometriosis were comparable between groups. Endometriosis was present in 4/6 hypoER-a females but in only 1/6 controls. HypoER-a animals had endometriosis in the uterus (2 cases), cervix (1 case), fallopian tube (2), ovary (2) and colon (1). The control animal had endometriosis in the uterus. ARID1A was retained in all tissues tested, including cases with endometriosis. WT-1 was positive in both epithelium and stroma for all endometriosis lesions. ER- a was negative in HypoER-a but not control endometriosis; PR was patchy positive in normal endometrium. PAX-8 stained rhesus tissue as would be expected in human analogs. One EnOC was identified in a hypoER-a animal that also had endometriosis. Conclusions: We have successfully created a nonhuman primate model that increases endometriosis penetrance. We also demonstrated parity between rhesus and human female endometriosis and EAOC by gross and histologic examination. Immunohistochemistry demonstrates WT-1 consistently stains endometrial glands and stroma in endometriosis. There was one animal with an EAOC in association with endometriosis. The rhesus macaque poses a higher order animal model for ongoing research in EAOC.

Endometriosis and risk of ovarian cancer

Endometriosis is common in premenopausal women and affects about 10% of women of reproductive age. It is a benign condition but demonstrates malignant behaviour with recurrences and metastases. Its tendency to increase the risk of specific subtypes of ovarian cancer is being discussed, because they exhibit specific clinical features that distinguish them from classical ovarian cancer. Malignant transformation of endometriosis goes through its transition to atypical endometriosis. Although endometriosis-associated ovarian carcinomas have a good prognosis, adequate follow-up and monitoring after treatment of endometriosis are recommended.

Endometriosis-associated ovarian carcinomas: insights into pathogenesis, diagnostics, and therapeutic targets-a narrative review.

Endometriosis is a benign gynecologic condition affecting up to one woman out of ten of reproductive age. It is defined by the presence of endometrial-like tissue in localizations outside of the uterine cavity. It often causes symptoms such as chronic pain, most frequently associated with the menstrual cycle, and infertility, but may also be oligo- or asymptomatic. There is evidence that some ovarian carcinoma (OC) histotypes, mainly the ovarian clear cell (OCCC) and endometrioid (EnOC) carcinoma, may arise from endometriosis. The most frequent genomic alterations in these carcinomas are mutations in the AT-rich interacting domain containing protein 1A (ARID1A) gene, a subunit of the SWI/SNF chromatin remodeling complex, and alterations in the phosphatidylinositol 3-kinase (PI3K)/AKT/mTOR pathway, which frequently co-occur. In ARID1A deficient cancers preclinical experimental data suggest different targetable mechanisms including epigenetic regulation, cell cycle, genomic instability, the PI3K/AKT/mTOR pathway, inflammatory pathways, immune modulation, or metabolic alterations as potential precision oncology approaches. Most of these strategies are relying on the concept of synthetic lethality in which tumors deficient in ARID1A are more sensitive to the different compounds. Some of these approaches are currently being or have recently been investigated in early clinical trials. The remarkably frequent occurrence of these mutations in endometriosis-associated ovarian cancer, the occurrence in a relatively young population, and the high proportion of platinum-resistant disease certainly warrants further investigation of precision oncology opportunities in this population. Furthermore, advanced knowledge about oncogenic mutations involved in endometriosis-associated ovarian carcinomas may be potentially useful for early cancer detection. However, this approach may be complicated by the frequent occurrence of somatic mutations in benign endometriotic tissue as recent studies suggest. In this narrative review of the current literature, we will discuss the data available on endometriosis-associated ovarian carcinoma, with special emphasis on epidemiology, diagnosis and molecular changes that could have therapeutic implications and clinical applicability in the future.

ARID1A protein expression in endometriosis-associated ovarian carcinomas

Epithelial ovarian carcinoma is leading cause of death among gynaecologic malignancies. Somatic mutation of ARID1A gene often observed in endometriosis-associated ovarian carcinoma cases. This mutation causes loss of ARID1A protein expression on tumor-bearing tissues. This study aims to investigate ARID1A protein expression in endometriosis-associated ovarian carcinoma cases in Indonesia. The archive of Formalin-fixed paraffin embedded (FFPE) tissue of 11 endometrial carcinomas (EC), 16 clear cell carcinoma (CCC), and 23 serous carcinomas (SC) from January 1, 2016, to December 31, 2017. The ARID1A expression were analyzed by using Kolmogorov Smirnov and Fisher’s Exact Tests. Majority of patients were older than 50 years (90%). Loss of ARID1A expression in tumor tissue was significantly low in the SC group (8.7%) compared to the EC group (27.3%) and the CCC group (62.5%) (p = 0.021). This study showed that ARID1A expression, was not associated with FIGO stage (p = 0,423), and with histological grade of the cases in EC group (p = 0,544) and SC group (p = 0,395). Loss of ARID1A expression was more frequently found in EC and CCC cases. Loss of ARID1A expression was not associated with FIGO stage and histological grade.

(Partial) Loss of BAF250a (ARID1A) in rectovaginal deep-infiltrating endometriosis, endometriomas and involved pelvic sentinel lymph nodes.

Loss of protein BAF250a (ARID1A) expression is present in women with rectovaginal deep-infiltrating endometriosis (DIE) and endometriosis affecting the pelvic sentinel lymph nodes (PSLN). Partial loss of protein BAF250a was found in some of our patient samples, comprising all endometriosis entities, including rectovaginal DIE and endometriosis affecting the PSLN. Loss of BAF250a (BRG-associated factor 250a)/ARIDIA (AT-rich interactive domain 1A) protein expression was identified among endometriosis-associated ovarian carcinomas and ovarian endometriosis, and this phenomenon was described as a possible early event in the transformation of endometriosis into cancer. DIE affecting the bowel/rectovaginal site is the most aggressive presentation of endometriosis and its 'risk' of malignant transformation has not been studied so far. We evaluated the immunohistochemical expression of BAF250a protein in 70 samples from patients enrolled in this study who were surgically treated at a tertiary center, university Hospital. The samples submitted to investigation were from rectovaginal DIE (n= 25/30), endometriosis affecting the PSLN (n= 5/7), ovarian endometriosis (n= 20/20) and endometrium from patients without endometriosis used as controls (n= 20/20). Partial loss (i.e. in one tissue section some cells stained positive for BAF250a while other cells, usually an adjacent group, were negative) of BAF250a protein was identified in 36% (9/25) of rectovaginal DIE samples, 40% (2/5) of endometriosis lesions involving the PSLN, 30% (6/20) of endometriomas, and also in 25% (5/20) of endometrium from controls. We found no statistical correlation between occurrence of partial loss of BAF250a protein and the use or not of hormone medications (P = 0.106), cycle phase (P = 0.917) and stage of disease (P = 0.717). We only found partial loss of BAF250a protein expression, and in a small population of women, with relatively high frequency in all benign tissues assessed in the present analysis. Therefore, this finding alone should not be correlated directly with the risk of malignant transformation in these lesions. The occurrence of partial loss of BAF250a protein expression in women with rectovaginal DIE and endometriosis affecting the PSLN is described for the first time. The value of this finding as a predictor of malignant transformation in endometriosis must still be clarified and further studied in association with other molecular events, such as PTEN (phosphatase and tensin homolog) deletion and PIK3CA (phosphatidylinositol-4,5-bisphosphate 3-kinase catalytic subunit alpha) mutation. We might then be able to identify in the future which patients with endometriosis are at higher risk of cancer. This study was supported by an internal Charité grant to the Endometriosis Research Center and the authors declare no conflicts of interest.

Endometriosis-associated ovarian cancer

This article reviews recent advance in our understanding of ovarian endometriomas, with special reference of atypical epithelial features (atypical endometriosis) and its relationship to neoplasm. Mainly, two epithelial ovarian carcinoma subtypes, the ovarian clear cell carcinomas and the endometrioid ovarian carcinomas, have been molecularly and epidemiologically linked to endometriosis. The clear cell and endometrioid adenocarcinomas have common immunohistochemical markers, genetic changes are the same as atypical endometriosis. The occurrence of ARID1A mutations and alterations in the PI3K/AKT pathway in endometriosis and endometriosis-associated ovarian carcinomas, as well as the possible functional and clinical implications are discussed in this review. Therefore, development of a screening method that can detect mutations of ARID1A and activation of the PI3K/AKT pathway might enable early diagnosis of endometriosis associated ovarian cancers and endometrial cancers.

ARID1A Is Essential for Endometrial Function during Early Pregnancy.

AT-rich interactive domain 1A gene (ARID1A) loss is a frequent event in endometriosis-associated ovarian carcinomas. Endometriosis is a disease in which tissue that normally grows inside the uterus grows outside the uterus, and 50% of women with endometriosis are infertile. ARID1A protein levels were significantly lower in the eutopic endometrium of women with endometriosis compared to women without endometriosis. However, an understanding of the physiological effects of ARID1A loss remains quite poor, and the function of Arid1a in the female reproductive tract has remained elusive. In order to understand the role of Arid1a in the uterus, we have generated mice with conditional ablation of Arid1a in the PGR positive cells (Pgr cre/+ Arid1a f/f; Arid1a d/d). Ovarian function and uterine development of Arid1a d/d mice were normal. However, Arid1a d/d mice were sterile due to defective embryo implantation and decidualization. The epithelial proliferation was significantly increased in Arid1a d/d mice compared to control mice. Enhanced epithelial estrogen activity and reduced epithelial PGR expression, which impedes maturation of the receptive uterus, was observed in Arid1a d/d mice at the peri-implantation period. The microarray analysis revealed that ARID1A represses the genes related to cell cycle and DNA replication. We showed that ARID1A positively regulates Klf15 expression with PGR to inhibit epithelial proliferation at peri-implantation. Our results suggest that Arid1a has a critical role in modulating epithelial proliferation which is a critical requisite for fertility. This finding provides a new signaling pathway for steroid hormone regulation in female reproductive biology and furthers our understanding of the molecular mechanisms that underlie dysregulation of hormonal signaling in human reproductive disorders such as endometriosis.

Distinct β-catenin and PIK3CA mutation profiles in endometriosis-associated ovarian endometrioid and clear cell carcinomas.

We focused on the differences in molecular mechanisms in the early stages of endometriosis-associated ovarian endometrioid carcinoma (OEMCa) and ovarian clear cell carcinoma (OCCCa). Alterations in the β-catenin and PIK3CA genes, as well as expression of their associated markers, were investigated. Mutations in exon 3 of the β-catenin gene were identified in 21 (60%) of 35 OEMCas. The mutations were also detected in the coexisting nonatypical (52.4%) and atypical (73.3%) endometriosis, and the single-nucleotide substitutions were identical in most cases. In contrast, the mutations were not identified in any of the OCCCas and their coexisting endometriosis. PIK3CA mutations were observed in 11 (31.4%) of 35 OEMCas and 10 (35.7%) of 28 OCCCas. Ten of 11 OEMCas had PIK3CA mutations in exon 9, and eight of 10 OCCCas had them in exon 20. The same mutations were also detected in the coexisting nonatypical and/or atypical endometriosis in three OEMCas and four OCCCas. In addition, significant differences in the expression of pAkt, hepatocyte nuclear factor 1β, hypoxia-inducible factor 1α, p65, and inducible nitric oxide synthase were evident between the two types of tumors and their coexisting endometriosis. Distinct molecular events may occur in relatively early stages of tumorigenesis of endometriosis-associated OEMCas and OCCCas.

ARID1A Mutations and PI3K/AKT Pathway Alterations in Endometriosis and Endometriosis-Associated Ovarian Carcinomas

Endometriosis is a common gynecological disease affecting 6%–10% of women of reproductive age and is characterized by the presence of endometrial-like tissue in localizations outside of the uterine cavity as, e.g., endometriotic ovarian cysts. Mainly, two epithelial ovarian carcinoma subtypes, the ovarian clear cell carcinomas (OCCC) and the endometrioid ovarian carcinomas (EnOC), have been molecularly and epidemiologically linked to endometriosis. Mutations in the gene encoding the AT-rich interacting domain containing protein 1A (ARID1A) have been found to occur in high frequency in OCCC and EnOC. The majority of these mutations lead to a loss of expression of the ARID1A protein, which is a subunit of the SWI/SNF chromatin remodeling complex and considered as a bona fide tumor suppressor. ARID1A mutations frequently co-occur with mutations, leading to an activation of the phosphatidylinositol 3-kinase (PI3K)/AKT pathway, such as mutations in PIK3CA encoding the catalytic subunit, p110α, of PI3K. In combination with recent functional observations, these findings strongly suggest cooperating mechanisms between the two pathways. The occurrence of ARID1A mutations and alterations in the PI3K/AKT pathway in endometriosis and endometriosis-associated ovarian carcinomas, as well as the possible functional and clinical implications are discussed in this review.

Prevalence of Loss of Expression of DNA Mismatch Repair Proteins in Primary Epithelial Ovarian Tumors

Although different histologic subtypes of epithelial ovarian tumors have long been recognized, their molecular abnormalities have not been fully defined. We examined the prevalence of DNA mismatch repair (MMR) protein loss in these tumors. Tissue microarrays (TMA) of suspected ovarian carcinomas were stained for hMLH1, hMSH2, hMSH6, and hPMS2 and scored separately by 2 groups of investigators. Loss of staining (negative) or discrepant staining results on TMA were verified on whole-section slides. Intact (positive) staining results were also verified for an additional 25 randomly selected cases. Clinical data for cases demonstrating MMR protein loss were collected. A second set of TMA composed purely of mucinous tumors was also stained for antibodies to MMR proteins and scored by 1 group of investigators. TMA was an effective method for screening a large number of ovarian tumors for MMR protein expression, with a sensitivity of 100% for all 4 MMR proteins, and a specificity of 22.2%-53.8% for different MMR proteins. Of the primary epithelial tumors of the ovary, loss of expression of MMR proteins was significantly more common in the endometriosis-associated carcinomas (7/69; 10.1%) than in high-grade serous carcinomas (2/182; 1.1%): P=0.0021. The former group also showed more frequent loss of MMR proteins compared with mucinous intestinal-type carcinomas (0/32; P=0.0940). Cases within the group of endometriosis-associated carcinomas were endometrioid (2/29 cases), clear cell (1/27 cases), undifferentiated (1/8 cases), and mixed carcinomas with an endometrioid, clear cell, and/or undifferentiated component (3/5 cases). No loss of MMR protein expression was identified in epithelial tumors of other histologic subtypes. Our study demonstrated the loss of MMR protein expression in 10.1% of endometriosis-associated ovarian carcinomas. These results raise the possibility of selective screening for Lynch syndrome in patients with these types of ovarian carcinoma.

Loss of ARID1A/BAF250a-expression in endometriosis: a biomarker for risk of carcinogenic transformation?

AbstractMutations of the tumor-suppressor gene ARID1A result in the loss of protein expression of the BRG-associated factor 250a (BAF250a), a large subunit of transcription-regulating Human SWI/SNF complexes, which have an important role in the control of cell proliferation and tumor suppression. ARID1A mutations are particularly frequent in endometriosis-associated ovarian clear cell and endometrioid carcinomas, and were recently described as a possible key mechanism and early step in the transformation of endometriosis into cancer. Here, we examined the immunohistochemical expression pattern of BAF250a in a tissue microarray including 74 endometriosis and 30 endometrium samples. Ovarian cancer samples (n=136) served as a control. Epithelial BAF250a expression was assessable in 90/104 (87%) and stromal BAF250a expression in 95/104 (91%) of the endometriosis, and endometrium cases due to lack of adequate tissue in some spots. Complete lack of BAF250a expression was observed in three endometriomas (n=3/20, 15%) and one deep-infiltrating endometriosis sample (n=1/22, 5%), but in none of the peritoneal endometriosis (n=0/16) and eutopic endometrium samples (n=0/30). A comparison of the mean immunoreactivity scores revealed a significantly lower expression rate of BAF250a in endometriomas compared with normal endometrium (P<0.0005), as well as peritoneal (P=0.003) and deep-infiltrating endometriosis (P=0.02). Our data demonstrates that a complete loss of BAF250a expression is observable in some endometriotic lesions, especially in endometriomas. In addition, we report that a partial loss of BAF250a expression is occurring in the form of cell clusters indicating a clonal loss of BAF250a expression in these cells. The loss of expression of the tumor-suppressor protein BAF250a in some endometriomas possibly indicates a risk of malignant transformation in these cases, which could be of importance in the determination of individual treatment strategies. However, its role and value as a prognostic parameter in endometriosis needs to be further studied.

Endometriosis and malignoma

Malignant tumors arising from endometriosis are rare. A frequency of about 1% has been reported with in 80% the ovary, and in 20% extragonadal sites being affected. The most common extragonadal manifestations are the rectosigmoid and the rectovaginal septum. For extragonadal malignant tumors arising from endometriosis, complete resection followed by post-operative radiotherapy, possibly plus adjuvant progestin therapy, is the treatment of choice. Endometriosis-associated ovarian carcinomas are likely to present with lower stage disease and predominantly lower grade tumors. While their treatment follows that of common ovarian cancer, a poorer response to chemotherapy must be considered. As unopposed estrogen replacement therapy has been identified as a risk factor for the development of endometriosis-associated cancer, it is not recommended for hormone replacement therapy in women with a history of endometriosis. Loss of heterozygosity and mutations of the PTEN tumor suppressor gene may be early events of tumorigenesis. Endometriosis and its malignant transformation, perhaps, may serve as a suitable model in this regard. According to recent studies, endometriosis is associated with an increased relative risk of non-Hodgkin lymphoma.