The molecular pathology of ovarian serous borderline tumors

A case of malignant transformation of a serous borderline ovarian tumor effectively treated with BRAF/MEK inhibitor combination

We describe a patient diagnosed with a metastatic adenocarcinoma of Müllerian origin, harboring a BRAF V600E mutation, ten years after being treated for a serous borderline tumor (SBOT). While BRAF mutations in the setting of SBOTs are common, they have been typically associated with a low chance of transformation or recurrence. The therapeutic approach, which combined hormone inhibition with receptor tyrosine kinase inhibitors (dabrafenib and trametinib), has demonstrated notable and enduring efficacy. This is clinically evidenced through serial PET-CT scans with sustained responses and extended progression-free survival, and serologically confirmed by monitoring CA-125 levels. This case demonstrates the critical role of early next-generation sequencing in detecting actionable molecular changes in rare cancers and possible metastases. It provides valuable insights into treating uncommon Müllerian adenocarcinomas and underscores the importance of targeted therapies in achieving long-lasting treatment outcomes.

Molecular changes driving low-grade serous ovarian cancer and implications for treatment

Low-grade serous ovarian cancer was previously thought to be a subtype of high-grade serous ovarian cancer, but it is now recognized as a distinct disease with unique clinical and molecular behaviors. The disease may arise de novo or develop from a serous borderline ovarian tumor. Although it is more indolent than high-grade serous ovarian cancer, most patients have advanced metastatic disease at diagnosis and recurrence is common. Recurrent low-grade serous ovarian cancer is often resistant to standard platinum-taxane chemotherapy, making it difficult to treat with the options currently available. New targeted therapies are needed, but their development is contingent on a deeper understanding of the specific biology of the disease. The known molecular drivers of low-grade tumors are strong hormone receptor expression, mutations in the mitogen-activated protein kinase (MAPK) pathway (KRAS, BRAF, and NRAS), and in genes related to the MAPK pathway (NF1/2, EIF1AX, and ERBB2). However, MAPK inhibitors have shown only modest clinical responses. Based on the discovery of CDKN2A mutations in low-grade serous ovarian cancer, cyclin-dependent kinases 4 and 6 (CDK4/6) inhibitors are now being tested in clinical trials in combination with hormone therapy. Additional mutations seen in a smaller population of low-grade tumors include USP9X, ARID1A, and PIK3CA, but no specific therapies targeting them have been tested clinically. This review summarizes the clinical, pathologic, and molecular features of low-grade serous ovarian cancer as they are now understood and introduces potential therapeutic targets and new avenues for research.

Eosinophilic Cells in Ovarian Borderline Serous Tumors as a Predictor of BRAF Mutation

According to recent reports, ovarian serous borderline tumor (SBT) harboring the BRAF V600E mutation is associated with a lower risk of progression to low-grade serous carcinoma. Preliminary observations suggest that there may be an association between eosinophilic cells (ECs) and the above-mentioned mutation, so this study aimed to evaluate interobserver reproducibility for assessing ECs. Forty-two samples of SBTs were analyzed for ECs with abundant eosinophilic cytoplasm. Immunohistochemical staining and genetic pro-filing were performed in all cases to verify the BRAF V600E mutation. A BRAF V600E mutation was found in 19 of 42 (45%) cases. Inter-observer reproducibility in the assessment of ECs was substantial (κ = 0.7). The sensitivity and specificity for predicting the mutation were 79% and 91%, respectively. Patients with BRAF-mutated SBTs were significantly younger than those without mutation (p = 0.005). SBTs with BRAF mutation were less likely to be accompanied by non-invasive implants than wild-type SBT: 12% (2/17) versus 33% (6/18). Seven cases were excluded due to incomplete cytoreductive surgery. Nevertheless, Fisher's exact test showed no significant differences between the two groups (p = 0.228). Overall, this study strengthens the idea that ECs in ovarian SBTs may represent a mutation with prognostic significance, which can serve as a primary screening test for BRAF V600E mutation in this pathologic entity.

Molecular landscape of borderline ovarian tumours: A systematic review

Borderline ovarian tumours (BOTs) show intriguing characteristics distinguishing them from other ovarian tumours. The aim of the systematic review was to analyse the spectrum of molecular changes found in BOTs and discuss their significance in the context of the overall therapeutic approach. The systematic review included articles published between 2000 and 2023 in the databases: PubMed, EMBASE, and Cochrane. After a detailed analysis of the available publications, we qualified for the systematic review: 28 publications on proto-oncogenes: BRAF, KRAS, NRAS, ERBB2, and PIK3CA, 20 publications on tumour suppressor genes: BRCA1/2, ARID1A, CHEK2, PTEN, 4 on adhesion molecules: CADM1, 8 on proteins: B-catenin, claudin-1, and 5 on glycoproteins: E-Cadherin. In addition, in the further part of the systematic review, we included eight publications on microsatellite instability and three describing loss of heterozygosity in BOT. Molecular changes found in BOTs can vary on a case-by-case basis, identifying carcinogenic mutations through molecular analysis and developing targeted therapies represent significant advancements in the diagnosis and treatment of ovarian malignancies. Molecular studies have contributed significantly to our understanding of BOT pathogenesis, but substantial research is still required to elucidate the relationship between ovarian neoplasms and extraneous disease, identify accurate prognostic indicators, and develop targeted therapeutic approaches.

Do survivors of borderline ovarian tumors have susceptibility to secondary primary malignancies? A SEER population-based study

OBJECTIVE

To describe the risk of women who have survived borderline ovarian tumors (BOT) developing second primary malignancies (SPM).

METHODS

This work employed the Surveillance, Epidemiology, and End Results (SEER) Program to conduct a retrospective study of patients diagnosed with BOT. The SEER stat software was used to calculate the standardized incidence ratio (SIR). Cases with pathologic diagnosis and for which information on prognostic factors were available were obtained and analyzed using the Fine and Gray model, with non-SPM death as a competing event.

RESULTS

The risk of developing SPM among BOT survivors was not elevated compared with that expected in the general population (SIR 0.88, 95% confidence interval [CI] 0.80-0.96) between 1975 and 2017. Of 3661 patients with BOT diagnosed between 1977 and 2000, 477 patients (13.03%) experienced the development of SPM during the median follow up of 19.43 years and the cumulative incidence of SPM over a span of 25 years was 15.52%. Patients with mucinous BOT (P = 0.028), age older than 50 years (P < 0.001), or no lymph node dissection (P = 0.042), had a higher cumulative incidence of SPM in univariate analysis. In the multivariable competing risk analysis, performing lymphadenectomy (subdistribution hazard ratios [sdHR] 0.79, 95% CI 0.64-0.98), age (sdHR 1.03, 95% CI 1.02-1.03) could strongly predict the risk of SPM.

CONCLUSION

In contrast to ovarian cancer, women with BOT were not more prone to develop SPM.

KRAS mutation in primary ovarian serous borderline tumors correlates with tumor recurrence

Oncogenic activation of the mitogen-activated protein kinase (MAPK) pathway due to KRAS or BRAF gain-of-function mutation is frequently found in ovarian serous borderline tumor (SBT) and their extraovarian implants. We investigated mutational status of KRAS and BRAF of the primary ovarian SBTs that had a high stage presentation in correlation with clinical outcome. Among 39 consecutive primary SBTs with either invasive implants (20 cases) or non-invasive implants (19 cases), KRAS and BRAF mutational analysis was informative in 34 cases. Sixteen cases (47%) harbored a KRAS mutation, while 5 cases (15%) had a BRAF V600E mutation. High-stage disease (IIIC) was seen in 31% (5/16) of patients with a KRAS mutation and 39% (7/18) of patients without a KRAS mutation (p = 0.64). KRAS mutations were present in 9/16 (56%) tumors with invasive implants/LGSC versus 7/18 (39%) tumors with non-invasive implants (p = 0.31). BRAF mutation was seen in 5 cases with non-invasive implants. Tumor recurrence was seen in 31% (5/16) of patients with a KRAS mutation, compared to 6% (1/18) of patients without a KRAS mutation (p = 0.04). A KRAS mutation predicted an adverse disease-free survival (31% survival at 160 months) compared to those with wild-type KRAS (94% at 160 months; log-rank test, p = 0.037; HR 4.47). In conclusion, KRAS mutation in primary ovarian SBTs is significantly associated with a worse disease-free survival, independent of the high tumor stage or histological subtypes of extraovarian implant. KRAS mutation testing of primary ovarian SBT may servce as a useful biomarker for tumor recurrence.

Unusual Ovarian Tumors With Endometrioid Proliferations Co-Expressing Estrogen Receptor and CDX-2 Arising in Cystadenofibromatous Background: Report of 3 Cases

This report describes 3 cases of ovarian tumors with unusual glandular proliferations co-expressing estrogen receptor and CDX-2 by immunohistochemistry set in cystadenofibromatous background. Targeted next-generation sequencing was performed on the cyst lining epithelium and glandular proliferations for all cases; CTNNB1 mutations were detected in the glandular proliferations of all neoplasms. The cyst lining of case 1 demonstrated a different CTNNB1 mutation from the matched glandular proliferation. No mutations were detected in the cyst lining from case 2. The cyst lining and glandular proliferation for case 3 harbored identical ATM and PIK3CA mutations with an additional CTNNB1 mutation in the glandular proliferation. To our knowledge, this is the first reported series of endometrioid proliferations with co-expression of estrogen receptor and CDX-2 in cystadenofibromatous background.

Low grade serous ovarian cancer - A rare disease with increasing therapeutic options

High-grade serous ovarian cancers (HGSOCs) most commonly arise from the fimbrial end of the fallopian tube and harbor TP53 gene mutations. In contrast, low-grade serous ovarian cancers (LGSOCs) appear to have different pathological, epidemiological, and clinical features and should be seen as a distinct serous epithelial ovarian cancer subtype. Our current understanding of LGSOC is limited, and treatment has generally been derived from the more common HGSOCs due to a lack of separate trial data. LGSOCs are characterized by slow tumor growth and are assumed to develop from serous borderline ovarian tumors as precursors. These cancers are often estrogen-receptor positive and show an activated mitogen-activated protein kinase pathway together with KRAS and BRAF mutations and, rarely, TP53 mutations. These characteristics are now commonly used to guide therapeutical decision making and, consequently, a substantial part of treatment consists of maintenance with endocrine treatment, thus balancing disease stabilization and mild toxicity. Additionally, new trials are ongoing that examine the role of targeted therapies such as MEK inhibitors in combination with endocrine treatments. The purpose of this work is to summarize current knowledge and present ongoing trial efforts for LGSOCs.

ANXA2P2: A Potential Immunological and Prognostic Signature in Ovarian Serous Cystadenocarcinoma via Pan-Carcinoma Synthesis

Background

Although the effect of pseudogene ANXA2P2 on some tumors has been reported in a few literatures, the therapeutic potential and prognostic value of ANXA2P2 in ovarian serous cystadenocarcinoma (OV) have not been elucidated.

Methods

The correlation for ANXA2P2 expression patterns to prognostic characteristics, tumor immune microenvironment, immune cell infiltration level, tumor mutation burden (TMB), tumor microsatellite instability (MSI), drug sensitivity, and pathway function enrichment were investigated in pan-carcinoma via TCGA and GTEx databases. Subsequently, the role of ANXA2P2 expression levels in the pathway enrichments and prognosis prediction in OV were further explored using weighted correlation network analysis (WGCNA) analysis, gene mutation analysis, and risk-independent prognostic analysis.

Results

ANXA2P2 was frequently overexpressed in a variety of tumors compared with normal tissues. The correlation analysis for prognostic characteristics, tumor immune microenvironment, immune cell infiltration level, TMB, MSI, drug sensitivity, and pathway function enrichment revealed that ANXA2P2 expression patterns might deal a significant impact on the pathogenesis, development, and prognosis of various tumors. Then, GSVA, GSEA, WGCNA, gene mutation, and independent prognostic analysis for OV have indicated that high expression in ANXA2P2 could be mostly enriched in TNF-α signaling-via-NF-κB, epithelial-mesenchymal transition, apical junction, IL-6-JAK STAT3 signaling, etc., which were also proved to act as crucial factors on tumorigenesis, development, invasion, and metastasis. The mutation of TP53 (94%), TTN (24%), and CSMD3 (9%) in the biological process of tumor had been confirmed by relevant studies. Finally, the independent prognostic analysis demonstrated that ANXA2P2 expression in OV contributes greatly to the dependability of 3- and 5-year survival prediction.

Conclusion

In summary, our findings might provide a helpful foundation for prospective explorative researches, afford new strategies for the clinical treatment, deal prognosis prediction, and give new hope for OV patients.

Nanomaterial-based biosensor developing as a route toward in vitro diagnosis of early ovarian cancer

The grand challenges of ovarian cancer early diagnosis have led to an alarmingly high mortality rate from ovarian cancer (OC) in the past half century. In vitro diagnosis (IVD) has great potential in the early diagnosis of OC through non-invasive and dynamic analysis of biomarkers. However, common IVDs often fail to provide reliable test results due to lack of sensitivity, specificity, and convenience. In recent years, the discovery of new biomarkers and the progress of nanomaterials can solve the shortcomings of traditional IVD for early OC. These emerging biosensors based on nanomaterials offer great improvements in convenience, speed, selectivity, and sensitivity of IVD. In this review, we firstly systematically summarized the limits of commercial IVD biosensors of OC and the latest discovery of new biomarkers for OC. The representative optimization strategies for six potential ovarian cancer biomarkers are systematically discussed with emphasis on nanomaterial selection and the design of detection principles. Then, various strategies adopted by emerging biosensors based on nanomaterials are also introduced in detail, including optical, electrochemical, microfluidic, and surface plasmon sensors. Finally, current challenges of early OC IVD are proposed, and future research directions on this promising field are also discussed.

•

Failure to diagnose OC early will lead to high mortality.

•

The detection of OC-related biomarkers by IVD method will achieve early diagnosis of OC.

•

The development of nanomaterials-based biosensors is expected to enhance efficiency of detection.

•

Strategies and progress for nanomaterials-based biosensors are systematically reviewed.

Synergistic AHR Binding Pathway with EMT Effects on Serous Ovarian Tumors Recognized by Multidisciplinary Integrated Analysis

Epithelial ovarian cancers (EOCs) are fatal and obstinate among gynecological malignancies in advanced stage or relapsed status, with serous carcinomas accounting for the vast majority. Unlike EOCs, borderline ovarian tumors (BOTs), including serous BOTs, maintain a semimalignant appearance. Using gene ontology (GO)-based integrative analysis, we analyzed gene set databases of serous BOTs and serous ovarian carcinomas for dysregulated GO terms and pathways and identified multiple differentially expressed genes (DEGs) in various aspects. The SRC (SRC proto-oncogene, non-receptor tyrosine kinase) gene and dysfunctional aryl hydrocarbon receptor (AHR) binding pathway consistently influenced progression-free survival and overall survival, and immunohistochemical staining revealed elevated expression of related biomarkers (SRC, ARNT, and TBP) in serous BOT and ovarian carcinoma samples. Epithelial-mesenchymal transition (EMT) is important during tumorigenesis, and we confirmed the SNAI2 (Snail family transcriptional repressor 2, SLUG) gene showing significantly high performance by immunohistochemistry. During serous ovarian tumor formation, activated AHR in the cytoplasm could cooperate with SRC, enter cell nuclei, bind to AHR nuclear translocator (ARNT) together with TATA-Box Binding Protein (TBP), and act on DNA to initiate AHR-responsive genes to cause tumor or cancer initiation. Additionally, SNAI2 in the tumor microenvironment can facilitate EMT accompanied by tumorigenesis. Although it has not been possible to classify serous BOTs and serous ovarian carcinomas as the same EOC subtype, the key determinants of relevant DEGs (SRC, ARNT, TBP, and SNAI2) found here had a crucial role in the pathogenetic mechanism of both tumor types, implying gradual evolutionary tendencies from serous BOTs to ovarian carcinomas. In the future, targeted therapy could focus on these revealed targets together with precise detection to improve therapeutic effects and patient survival rates.

Dysregulated Immunological Functionome and Dysfunctional Metabolic Pathway Recognized for the Pathogenesis of Borderline Ovarian Tumors by Integrative Polygenic Analytics

The pathogenesis and molecular mechanisms of ovarian low malignant potential (LMP) tumors or borderline ovarian tumors (BOTs) have not been fully elucidated to date. Surgery remains the cornerstone of treatment for this disease, and diagnosis is mainly made by histopathology to date. However, there is no integrated analysis investigating the tumorigenesis of BOTs with open experimental data. Therefore, we first utilized a functionome-based speculative model from the aggregated obtainable datasets to explore the expression profiling data among all BOTs and two major subtypes of BOTs, serous BOTs (SBOTs) and mucinous BOTs (MBOTs), by analyzing the functional regularity patterns and clustering the separate gene sets. We next prospected and assembled the association between these targeted biomolecular functions and their related genes. Our research found that BOTs can be accurately recognized by gene expression profiles by means of integrative polygenic analytics among all BOTs, SBOTs, and MBOTs; the results exhibited the top 41 common dysregulated biomolecular functions, which were sorted into four major categories: immune and inflammatory response-related functions, cell membrane- and transporter-related functions, cell cycle- and signaling-related functions, and cell metabolism-related functions, which were the key elements involved in its pathogenesis. In contrast to previous research, we identified 19 representative genes from the above classified categories (IL6, CCR2 for immune and inflammatory response-related functions; IFNG, ATP1B1, GAS6, and PSEN1 for cell membrane- and transporter-related functions; CTNNB1, GATA3, and IL1B for cell cycle- and signaling-related functions; and AKT1, SIRT1, IL4, PDGFB, MAPK3, SRC, TWIST1, TGFB1, ADIPOQ, and PPARGC1A for cell metabolism-related functions) that were relevant in the cause and development of BOTs. We also noticed that a dysfunctional pathway of galactose catabolism had taken place among all BOTs, SBOTs, and MBOTs from the analyzed gene set databases of canonical pathways. With the help of immunostaining, we verified significantly higher performance of interleukin 6 (IL6) and galactose-1-phosphate uridylyltransferase (GALT) among BOTs than the controls. In conclusion, a bioinformatic platform of gene-set integrative molecular functionomes and biophysiological pathways was constructed in this study to interpret the complicated pathogenic pathways of BOTs, and these important findings demonstrated the dysregulated immunological functionome and dysfunctional metabolic pathway as potential roles during the tumorigenesis of BOTs and may be helpful for the diagnosis and therapy of BOTs in the future.

A Case of Paratubal Serous Borderline Tumor Driven by a Somatic BRAF Mutation in an Adolescent Patient

BACKGROUND

We describe a rare paratubal serous borderline tumor occurring in an adolescent and provide insight into its molecular underpinnings.

CASE

A 14-year-old girl presented with irregular menstrual cycles and a large right pelvic mass. Computed tomography imaging revealed a cystic neoplasm arising from the right ovary with peripheral calcification. During laparotomy, a cystic tumor located at the right parametrium independent of the fallopian tube was identified. The ovary was intact and the tumor was successfully removed. Intraoperative diagnosis using the frozen section technique and subsequent pathology revealed a paratubal serous borderline tumor. Molecular analyses revealed a chromosomally stable tumor genome and a pathogenic somatic mutation (c.1799 T > A, p.Val600Glu) in the B-Raf proto-oncogene, serine/threonine kinase (BRAF) gene.

SUMMARY AND CONCLUSION

This case shows that the BRAF p.Val600Glu mutation likely acts as an oncogenic driver in this rare neoplasm.

Targeting KRAS in Cancer: Promising Therapeutic Strategies

Simple Summary

Since the Kirsten rat sarcoma viral oncogene homolog (KRAS) is mutated in about 25% of all human cancers and is at the center of pathways involved in tumorigenesis, it is necessary to compile and highlight the novel therapeutic strategies behind targeting this oncoprotein in cancer. Over the years, many have studied various methods to directly target KRAS with no success. Fortunately, there has been more success in targeting other proteins along the RAS pathway to yield a therapeutic response. However, some recent findings show promising results indicating that we are one step closer to developing an effective inhibitor that directly targets KRAS. The review presented here summarizes these recent findings and emphasizes the need to continue the search for the most optimal KRAS inhibitor that can be used to treat and potentially even cure certain tumor types.

Abstract

The Kirsten rat sarcoma viral oncogene homolog (KRAS) is mutated in approximately 25% of all human cancers and is known to be a major player promoting and maintaining tumorigenesis through the RAS/MAPK pathway. Over the years, a large number of studies have identified strategies at different regulatory levels to tackle this ‘difficult-to-target’ oncoprotein. Yet, the most ideal strategy to overcome KRAS and its downstream effects has yet to be uncovered. This review summarizes the role of KRAS activating mutations in multiple cancer types as well as the key findings for potential strategies inhibiting its oncogenic behavior. A comprehensive analysis of the different pathways and mechanisms associated with KRAS activity in tumors will ultimately pave the way for promising future work that will identify optimum therapeutic strategies.

Comprehensive genomic profiling reveals ubiquitous KRAS mutations and frequent PIK3CA mutations in ovarian seromucinous borderline tumor

The molecular underpinnings of seromucinous borderline tumor (SMBT) - an uncommon ovarian epithelial neoplasm characterized by association with endometriosis, frequent bilateral ovarian involvement, and occasional progression to invasive carcinoma - remain poorly understood. Here, we sought to comprehensively characterize the mutational landscape of SMBT and elucidate the clonal relationship between bilateral ovarian SMBTs. We also compared the mutational profiles between SMBTs and concurrent invasive carcinomas. Formalin-fixed, paraffin-embedded tissue specimens were retrieved from 28 patients diagnosed with SMBT. Massively parallel sequencing of 409 cancer-related genes was conducted to identify somatic mutations in 33 SMBT samples and four concurrent invasive carcinoma specimens. TERT promoter mutations were assessed by Sanger sequencing, whereas immunohistochemistry was used as a surrogate tool for detecting deletions or epigenetic silencing of relevant tumor suppressor genes. Twenty-six (92.9%) of the 28 patients were diagnosed with stage I SMBTs. Seven (25%) cases showed bilateral ovarian involvement and 13 (46%) had concomitant endometriosis. Concurrent ovarian carcinomas were identified in three patients, whereas one case had a synchronous endometrial carcinoma. Somatic mutations in the KRAS, PIK3CA, and ARID1A genes were identified in 100, 60.7, and 14.3% of SMBT samples, respectively. In contrast, TERT promoter mutations and DNA mismatch repair deficiencies were absent. Sequencing of paired specimens from patients with bilateral SMBT revealed the presence of at least two shared somatic mutations, suggestive of a clonal relationship. Similarly, we identified shared somatic mutations between SMBT samples and concurrent ovarian carcinoma specimens. Taken together, these findings demonstrated a distinct mutational landscape of SMBT in which (1) KRAS is invariably mutated, (2) PIK3CA is frequently mutated, and (3) TERT promoter mutations and DNA mismatch repair deficiencies are absent. Our findings represent the first extensive characterization of this rare ovarian neoplasm, with potential implications for disease classification and molecular diagnostics.

[Borderline ovarian tumours: CNGOF Guidelines for clinical practice - Biopathology of ovarian borderline tumors]

OBJECTIVES

Ovarian borderline tumors (OBT) represent a heterogeneous group of lesions with specific management for each histological subtype. Thus, the correct histological diagnosis is mandatory.

MATERIAL AND METHODS

References were searched by PubMed from January 2000 to January 2018 and original articles in French and English literature were selected.

RESULTS AND CONCLUSIONS

OBT should be classified according to the last WHO classification. Any micro-invasion (foci<5mm) or microcarcinoma (foci<5mm with nuclear atypia and desmoplastic stromal reaction) should be indicated in the pathology report. In case of serous OBT, variants (classical or the micropapillary/cribriform) should be indicated (grade C). The peritoneal implants associated with OBT, should be classified as invasive or noninvasive, according to the extension into the underlying adipous tissue. If no adipous tissue is seen the term undetermined should be used (grade B). In case of mucinous OBT bilateral and/or with peritoneal implants or peritoneal pseudomyxoma a search for primitive gastrointestinal, appendiceal or biliopancreatic tumor should be performed (grade C). In case of OBT, a thorough sampling of the tumor is recommended, with 1 block/cm and 2 blocks/cm in case of mucinous OBT, serous OBT micropapillary variant, OBT with intraepithelial carcinoma or/and micro-invasion. Peritoneal implants should be examined in toto. Omentum without macroscopic lesion should be sampled in 4 to 6 blocks (grade C). In case of ovarian cyst suspicious for OBT, fine needle aspiration is not recommended (grade C). In case of ovarian tumor suspicious for OBT, intraoperative examination should be performed by a gynecological pathologist (grade C).

Clinicopathologic, Immunohistochemical, and Molecular Characteristics of Ovarian Serous Carcinoma With Mixed Morphologic Features of High-grade and Low-grade Serous Carcinoma

Despite the current classification of high-grade serous carcinoma (HGSCA) and low-grade serous carcinoma (LGSCA) as mutually exclusive diseases based on morphology and molecular pathogenesis, cases with mixed morphologic features of HGSCA and LGSCA have been reported. Herein we assess the clinicopathologic, immunohistochemical (IHC), and molecular genetic characteristics of a group of these cases, which we termed indeterminate grade serous carcinoma (IGSCA) in comparison with groups of HGSCA and LGSCA. Using the World Health Organization (WHO) classification criteria, we selected 27 LGSCA and 19 IGSCA for detailed morphologic study. Thirteen classic HGSCA, 19 classic LGSCA, and 19 IGSCA were selected for p53 and BRAF V600E IHC and molecular genetic testing by next-generation sequencing. IGSCA showed the architectural patterns of invasion of LGSCA, but with higher grade nuclear features focally and a mitotic index intermediate between LGSCA and HGSCA. Few cases in the IGSCA group showed mutant TP53 by IHC or sequencing (4/18, 22.2%), 1 case had mutant BRAF non-V600E by sequencing, and 1 had an NRAS mutation. When present, the mutations were identical in the low-grade and high-grade areas. The IGSCA group had a long-term survival similar to the classic HGSCA group. IGSCA with mixed morphologic features of HGSCA and LGSCA is a rare and potentially clinically aggressive variant of serous carcinoma. Their distinct morphologic, but heterogenous molecular features, including low frequency of TP53 and BRAF mutations suggest that these rare tumors may have a different pathogenesis pathway compared with classic HGSCA and classic LGSCA.

Does lymph node ratio have any prognostic significance in maximally cytoreduced node-positive low-grade serous ovarian carcinoma?

PURPOSE

To determine the prognostic impact of the lymph node ratio (LNR) in node-positive low-grade serous ovarian cancer (LGSOC).

METHODS

We retrospectively reviewed women with LGSOC who had undergone maximal cytoreduction followed by standard chemotherapy in 11 centers from Turkey during a study period of 20 years. Sixty two women with node-positive LGSOC were identified. LNR was defined as the number of metastatic lymph nodes (LNs) divided by the number of total LNs removed. We grouped patients pursuant to the LNR as LNR ≤ 0.09 and LNR > 0.09. The prognostic value of LNR was investigated by employing the univariate log-rank test and multivariate Cox-regression model.

RESULTS

With a median follow-up of 45 months, the 5-year progression-free survival (PFS) rates were 61.7% for women with LNR ≤ 0.09 and 32.0% for those with LNR > 0.09 (p = 0.046) whereas, the 5-year overall survival (OS) rates were 72.8% for LNR ≤ 0.09 and 54.7% for LNR > 0.09 (p = 0.043). On multivariate analyses, lymphovascular space invasion (LVSI) (Hazard Ratio [HR] 4.18, 95% confidence interval [CI] 1.88-9.27; p < 0.001), omental involvement (HR 3.48, 95% CI 1.36-8.84; p = 0.009) and LNR > 0.09 (HR 3.51, 95% CI 1.54-8.03; p = 0.003) were adverse prognostic factors for PFS. Additionally, LVSI (HR 6.56, 95% CI 2.33-18.41; p < 0.001), omental involvement (HR 6.34, 95% CI 1.86-21.57; p = 0.003) and LNR > 0.09 (HR 7.20, 95% CI 2.33-22.26; p = 0.001) were independent prognostic factors for decreased OS.

CONCLUSION

LNR > 0.09 seems to be an independent prognosticator for decreased survival outcomes in LGSOC patients who received maximal cytoreduction followed by standard adjuvant chemotherapy.

The Diagnosis, Treatment, Prognosis and Molecular Pathology of Borderline Ovarian Tumors: Current Status and Perspectives

Borderline ovarian tumors (BOTs) are a type of low malignant potential tumor that is typically associated with better outcomes than ovarian cancer. Indeed, its 10-year survival rate is as high as 95%. However, there is a small subset of patients who experience relapse and eventually die. It has been shown that the prognosis of BOTs was based on pathological diagnosis, the age at diagnosis, pre-operative carbohydrate antigen 125 level, invasive implants, and micropapillary patterns. Now the molecular-targeted therapy and molecular-genetic diagnosis have developed into a form of precision medicine. Recent studies on extensive molecular characterizations and molecular pathological mechanisms of BOTs have helped us understand the genomic landscapes of BOTs, and therefore BOTs could be reclassified into biologically and clinically more accurate and effective subtypes. The purpose of this review is to summarize current status for the diagnosis and treatment of BOTs and to describe the research progress on molecular pathologies, with a goal of providing a theoretical perspective for the diagnosis and treatment of BOTs.

Establishment and characterization of a cell line and patient-derived xenograft (PDX) from peritoneal metastasis of low-grade serous ovarian carcinoma

Peritoneal spread indicates poor prognosis in patients with serous ovarian carcinoma (SOC) and is generally treated by surgical cytoreduction and chemotherapy. Novel treatment options are urgently needed to improve patient outcome. Clinically relevant cell lines and patient-derived xenograft (PDX) models are of critical importance to therapeutic regimen evaluation. Here, a PDX model was established, by orthotopic engraftment after subperitoneal tumor slurry injection of low-grade SOC, resulting in an early-stage transplantable peritoneal metastasis (PM)-PDX model. Histology confirmed the micropapillary and cribriform growth pattern with intraluminal tumor budding and positivity for PAX8 and WT1. PM-PDX dissociated cells show an epithelial morphotype with a 42 h doubling time and 40% colony forming efficiency, they are low sensitive to platinum derivatives and highly sensitive to paclitaxel (IC50: 6.3 ± 2.2 nM, mean ± SEM). The patient primary tumor, PM, PM-PDX and derived cell line all show a KRAS c.35 G > T (p.(Gly12Val)) mutation and show sensitivity to the MEK inhibitor trametinib in vitro (IC50: 7.2 ± 0.5 nM, mean ± SEM) and in the PM mouse model. These preclinical models closely reflecting patient tumors are useful to further elucidate LGSOC disease progression, therapy response and resistance mechanisms.

MR imaging findings of low-grade serous carcinoma of the ovary: comparison with serous borderline tumor

PURPOSE

To assess MR imaging findings of low-grade serous carcinoma (LGSC) of the ovary compared with those of serous borderline tumor (SBT).

METHODS

Twenty-four patients with histopathologically proven 7 LGSCs and 25 SBTs who underwent preoperative MR imaging were included. We retrospectively reviewed MR images and compared MR findings between the two pathologies.

RESULTS

The predominantly solid lesions were marginally more frequent in LGSCs than in SBTs (43% vs. 8%, p = 0.057). All predominantly cystic LGSCs were multilocular cystic lesions with mural nodules. Predominantly solid LGSCs exhibited pure solid masses in 2 of 3 and solid masses with intratumoral cysts in 1 of 3. Papillary growth pattern with internal branching was observed only in 18 of 25 SBTs. Signal intensity ratio on T2-weighted images (4.48 ± 1.55 vs. 8.40 ± 3.53, p < 0.01) and apparent diffusion coefficient (ADC) values (1.12 ± 0.21 vs. 1.73 ± 0.27 × 10^-3 mm²/s, p < 0.01) of solid components was significantly lower in LGSCs than in SBTs.

CONCLUSION

Compared with SBTs, lower signal intensity on T2-weighted images and lower ADC values were characteristic features of solid components in LGSCs. Papillary growth pattern with internal branching was not observed in LGSCs.

Maximal cytoreduction is related to improved disease-free survival in low-grade ovarian serous carcinoma

Objective:

To evaluate the factors predicting oncologic outcomes in low-grade ovarian serous carcinoma (LGOSC).

Methods:

Seventy patients with LGOSC were included in the study. According to the residual disease present at the end of the initial cytoreductive surgery (CRS), surgical outcomes are defined as follows: maximal CRS for absence of macroscopic residual tumors, optimal CRS for macroscopic residual tumors with diameters ranging from 0.1 to ⩽1 cm diameter, and suboptimal CRS for macroscopic residual tumors measuring >1 cm in diameter.

Results:

Five-year disease-free survival (DFS) and cancer-specific survival (CSS) were 61% and 83%, respectively. Surgical outcomes were suboptimal in 3 (4.3%) patients, optimal in 8 (11.4%) patients, and maximal in 59 (84.3%) patients. Stage and surgical outcomes were related to DFS ( p < 0.05). Compared with maximal CRS, the presence of residual tumors (suboptimal and optimal debulking) was related to threefold increased risk of disease failure (recurrence or progression) (hazard ratio [95% confidence interval] 3.00 [1.27–7.09]; P=0.012). CSS was associated with disease stage alone ( P=0.03). Advanced stage was related with lower DFS and CSS.

Conclusions:

Maximal CRS facilitates an improvement in DFS. Achieving no residual disease after the completion of surgery should be a cornerstone of LGOSC management.

Low-grade epithelial ovarian cancer: what a radiologist should know

Ovarian cancer accounts for the death of over 100,000 females every year and is the most lethal gynecological malignancy. Low-grade serous ovarian carcinoma (LGSOC) and high-grade serous ovarian carcinoma (HGSOC) have been found to represent two distinct entities based on their molecular differences, clinical course, and response to chemotherapy. Currently, all ovarian cancers are staged according to the revised staging system of the International Federation of Gynecology and Obstetrics (FIGO). Imaging plays an integral role in the diagnosis, staging, and follow-up of ovarian cancers. This review will be based on the two-tier grading system of epithelial ovarian cancers, with the main emphasis on serous ovarian cancer, and the role of imaging to characterize low-grade vs high-grade tumors and monitor disease recurrence during follow-up.

Markers of MEK inhibitor resistance in low-grade serous ovarian cancer: EGFR is a potential therapeutic target

BACKGROUND

Although low-grade serous ovarian cancer (LGSC) is rare, case-fatality rates are high as most patients present with advanced disease and current cytotoxic therapies are not overly effective. Recognizing that these cancers may be driven by MAPK pathway activation, MEK inhibitors (MEKi) are being tested in clinical trials. LGSC respond to MEKi only in a subgroup of patients, so predictive biomarkers and better therapies will be needed.

METHODS

We evaluated a number of patient-derived LGSC cell lines, previously classified according to their MEKi sensitivity. Two cell lines were genomically compared against their matching tumors samples. MEKi-sensitive and MEKi-resistant lines were compared using whole exome sequencing and reverse phase protein array. Two treatment combinations targeting MEKi resistance markers were also evaluated using cell proliferation, cell viability, cell signaling, and drug synergism assays.

RESULTS

Low-grade serous ovarian cancer cell lines recapitulated the genomic aberrations from their matching tumor samples. We identified three potential predictive biomarkers that distinguish MEKi sensitive and resistant lines: KRAS mutation status, and EGFR and PKC-alpha protein expression. The biomarkers were validated in three newly developed LGSC cell lines. Sub-lethal combination of MEK and EGFR inhibition showed drug synergy and caused complete cell death in two of four MEKi-resistant cell lines tested.

CONCLUSIONS

KRAS mutations and the protein expression of EGFR and PKC-alpha should be evaluated as predictive biomarkers in patients with LGSC treated with MEKi. Combination therapy using a MEKi with EGFR inhibition may represent a promising new therapy for patients with MEKi-resistant LGSC.

Markers of MEK inhibitor resistance in low-grade serous ovarian cancer: EGFR is a potential therapeutic target

Background

Although low-grade serous ovarian cancer (LGSC) is rare, case-fatality rates are high as most patients present with advanced disease and current cytotoxic therapies are not overly effective. Recognizing that these cancers may be driven by MAPK pathway activation, MEK inhibitors (MEKi) are being tested in clinical trials. LGSC respond to MEKi only in a subgroup of patients, so predictive biomarkers and better therapies will be needed.

Methods

We evaluated a number of patient-derived LGSC cell lines, previously classified according to their MEKi sensitivity. Two cell lines were genomically compared against their matching tumors samples. MEKi-sensitive and MEKi-resistant lines were compared using whole exome sequencing and reverse phase protein array. Two treatment combinations targeting MEKi resistance markers were also evaluated using cell proliferation, cell viability, cell signaling, and drug synergism assays.

Results

Low-grade serous ovarian cancer cell lines recapitulated the genomic aberrations from their matching tumor samples. We identified three potential predictive biomarkers that distinguish MEKi sensitive and resistant lines: KRAS mutation status, and EGFR and PKC-alpha protein expression. The biomarkers were validated in three newly developed LGSC cell lines. Sub-lethal combination of MEK and EGFR inhibition showed drug synergy and caused complete cell death in two of four MEKi-resistant cell lines tested.

Conclusions

KRAS mutations and the protein expression of EGFR and PKC-alpha should be evaluated as predictive biomarkers in patients with LGSC treated with MEKi. Combination therapy using a MEKi with EGFR inhibition may represent a promising new therapy for patients with MEKi-resistant LGSC.

Markers of MEK inhibitor resistance in low-grade serous ovarian cancer: EGFR is a potential therapeutic target

Background

Although low-grade serous ovarian cancer (LGSC) is rare, case-fatality rates are high as most patients present with advanced disease and current cytotoxic therapies are not overly effective. Recognizing that these cancers may be driven by MAPK pathway activation, MEK inhibitors (MEKi) are being tested in clinical trials. LGSC respond to MEKi only in a subgroup of patients, so predictive biomarkers and better therapies will be needed.

Methods

We evaluated a number of patient-derived LGSC cell lines, previously classified according to their MEKi sensitivity. Two cell lines were genomically compared against their matching tumors samples. MEKi-sensitive and MEKi-resistant lines were compared using whole exome sequencing and reverse phase protein array. Two treatment combinations targeting MEKi resistance markers were also evaluated using cell proliferation, cell viability, cell signaling, and drug synergism assays.

Results

Low-grade serous ovarian cancer cell lines recapitulated the genomic aberrations from their matching tumor samples. We identified three potential predictive biomarkers that distinguish MEKi sensitive and resistant lines: KRAS mutation status, and EGFR and PKC-alpha protein expression. The biomarkers were validated in three newly developed LGSC cell lines. Sub-lethal combination of MEK and EGFR inhibition showed drug synergy and caused complete cell death in two of four MEKi-resistant cell lines tested.

Conclusions

KRAS mutations and the protein expression of EGFR and PKC-alpha should be evaluated as predictive biomarkers in patients with LGSC treated with MEKi. Combination therapy using a MEKi with EGFR inhibition may represent a promising new therapy for patients with MEKi-resistant LGSC.

Electronic supplementary material

The online version of this article (10.1186/s12935-019-0725-1) contains supplementary material, which is available to authorized users.

Cell Origins of High-Grade Serous Ovarian Cancer

High-grade serous ovarian cancer, also known as high-grade serous carcinoma (HGSC), is the most common and deadliest type of ovarian cancer. HGSC appears to arise from the ovary, fallopian tube, or peritoneum. As most HGSC cases present with widespread peritoneal metastases, it is often not clear where HGSC truly originates. Traditionally, the ovarian surface epithelium (OSE) was long believed to be the origin of HGSC. Since the late 1990s, the fallopian tube epithelium has emerged as a potential primary origin of HGSC. Particularly, serous tubal intraepithelial carcinoma (STIC), a noninvasive tumor lesion formed preferentially in the distal fallopian tube epithelium, was proposed as a precursor for HGSC. It was hypothesized that STIC lesions would progress, over time, to malignant and metastatic HGSC, arising from the fallopian tube or after implanting on the ovary or peritoneum. Many clinical studies and several mouse models support the fallopian tube STIC origin of HGSC. Current evidence indicates that STIC may serve as a precursor for HGSC in high-risk women carrying germline BRCA1 or 2 mutations. Yet not all STIC lesions appear to progress to clinical HGSCs, nor would all HGSCs arise from STIC lesions, even in high-risk women. Moreover, the clinical importance of STIC remains less clear in women in the general population, in which 85–90% of all HGSCs arise. Recently, increasing attention has been brought to the possibility that many potential precursor or premalignant lesions, though composed of microscopically—and genetically—cancerous cells, do not advance to malignant tumors or lethal malignancies. Hence, rigorous causal evidence would be crucial to establish that STIC is a bona fide premalignant lesion for metastatic HGSC. While not all STICs may transform into malignant tumors, these lesions are clearly associated with increased risk for HGSC. Identification of the molecular characteristics of STICs that predict their malignant potential and clinical behavior would bolster the clinical importance of STIC. Also, as STIC lesions alone cannot account for all HGSCs, other potential cellular origins of HGSC need to be investigated. The fallopian tube stroma in mice, for instance, has been shown to be capable of giving rise to metastatic HGSC, which faithfully recapitulates the clinical behavior and molecular aspect of human HGSC. Elucidating the precise cell(s) of origin of HGSC will be critical for improving the early detection and prevention of ovarian cancer, ultimately reducing ovarian cancer mortality.

Age-dependent difference in impact of fertility preserving surgery on disease-specific survival in women with stage I borderline ovarian tumors

Background

This study was to determine age-specific impact of fertility preserving surgery on disease-specific survival in women with stage I borderline ovarian tumors (BOTs). Patients diagnosed during 1988–2000 were selected from The Surveillance, Epidemiology, and End Results (SEER) database. The age-specific impact of fertility preserving surgery and other risk factors were analyzed in patients with stage I BOTs using Cox proportion hazard regression models. Data from our hospital were collected during 1996–2017 to determine the prevalence of patients who had undergone fertility preserving surgery.

Results

Of a total 6295 patients in the SEER database, this study selected 2946 patients with stage T1 BOTs who underwent fertility preserving or radical surgery. Their median age at diagnosis was 45.0 years and the median follow-up time was 200 months. Fertility preserving surgery was performed in 1000/1751 (57.1%) patients < 50 years and in 1,81/1195 (15.1%) patients ≥50 years. Fertility preserving surgery was significantly associated with worse disease-specific survival only in patients ≥50 years. Increased age, stage T1c and mucinous histology were risk factors for overall patients or patients ≥50 years, but not for < 50 years. Data from our hospital showed that fertility preserving surgery was performed in 53.9 and 12.3%patients < 50 and ≥ 50 years with stage I disease, respectively.

Conclusion

Fertility preserving surgery is safe for women < 50 years with early staged BOTs, but it may decrease disease-specific survival in patients ≥50 years. Conservative surgery is performed at a relatively high rate in patients ≥50 years.

Electronic supplementary material

The online version of this article (10.1186/s13048-018-0423-y) contains supplementary material, which is available to authorized users.

BRAFV600E mutations and immunohistochemical expression of VE1 protein in low-grade serous neoplasms of the ovary

AIMS

The most common BRAF mutation in ovarian low-grade serous neoplasms (LGSNs) involves substitution of valine by glutamic acid at position 600 (V600E). Small studies have demonstrated high specificity of immunohistochemistry with mutation-specific monoclonal antibody VE1. We sought to investigate the expression of VE1 protein in LGSNs and its correlation with BRAF mutation-associated histological features and BRAF mutation status.

METHODS AND RESULTS

We reviewed pathology reports and available slides from ovarian serous borderline tumours (SBTs) and low-grade serous carcinomas (LGSCs) diagnosed between 2000 and 2012. VE1 immunohistochemistry was performed on formalin-fixed, paraffin-embedded tissue sections. Tumours with ≥50% positive cells were considered positive. Of 121 LGSNs, there were 73 SBTs, eight SBTs with micropapillary features (mpSBT) and 40 LGSCs (22 primary, 18 metastatic). VE1 was positive in 52% (38 of 73) of SBTs and 9% (two of 22) of primary LGSCs, and in none of the mpSBTs and metastatic LGSCs (P < 0.0001). Of 76 tumours with known mutation status, 42 (55%) harboured mutations, including BRAF^V600E (26, 34%), KRAS^G12D (eight, 11%), and KRAS^G12V (eight, 11%). BRAF^V600E mutations were present in 48% (25 of 52) of SBTs and 5% (one of 22) of LGSCs (P < 0.0001). VE1 was positive in 96% (25 of 26) of BRAF^V600E -mutated tumours and correlated with BRAF mutation-associated histological features (P < 0.0001).

CONCLUSIONS

BRAF^V600E mutations are significantly more common in SBTs than in LGSCs. Immunohistochemical expression of VE1 protein is associated strongly with BRAF^V600E mutation and BRAF mutation-associated histological features. VE1 immunohistochemistry is a reliable method for the detection of BRAF^V600E mutations.

Origins based clinical and molecular complexities of epithelial ovarian cancer

Ovarian cancer is the most lethal of all common gynaecological malignancies in women worldwide. Ovarian cancer comprises of >15 distinct tumor types and subtypes characterized by histopathological features, environmental and genetic risk factors, precursor lesions and molecular events during oncogenesis. Recent studies on gene signature profiling of different subtypes of ovarian cancer have revealed significant genetic heterogeneity between and within each ovarian cancer histological subtype. Thus, an immense interest have shown towards a more personalized medicine for understanding the clinical and molecular complexities of four major types of epithelial ovarian cancer (serous, endometrioid, clear cell, and mucinous). As such, further in depth studies are needed for identification of molecular signalling network complexities associated with effective prognostication and targeted therapies to prevent or treat metastasis. Therefore, understanding the metastatic potential of primary ovarian cancer and therapeutic interventions against lethal ovarian cancer for the development of personalized therapies is very much indispensable. Consequently, in this review we have updated the key dysregulated genes of four major subtypes of epithelial carcinomas. We have also highlighted the recent advances and current challenges in unravelling the complexities of the origin of tumor as well as genetic heterogeneity of ovarian cancer.

Malignant peritoneal mesothelioma in a woman with bilateral ovarian serous borderline tumour: Potential interactions between the two diseases

We report a case of a 59-year-old woman with peritoneal malignant mesothelioma and no previous exposure to asbestos with a diagnosis of bilateral ovarian serous borderline tumour with peritoneal implants one year before. We discuss the histopathological and immunohistochemical findings to explain possible and potential interactions between the two diseases. To our knowledge, the association of both serous borderline ovarian tumour and malignant peritoneal mesothelioma has never been described before in the same woman and in such a tight temporal connection. This finding raises numerous issues about the origin of the two tumours and further biomolecular studies are needed to fully understand the carcinogenetic process. From a clinical point of view, this case report can be useful to gynaecologists because it leads to recommend a careful examination of the peritoneal cavity during a surgical resection of borderline serous tumour. Moreover, it may suggest performing a close follow-up associated with a careful surveillance of the patient, especially in the case of micropapillary pattern, to oncologists. A complete clinical approach could help to detect sooner possible relapses or other metachronous malignancies.

•

Serous borderline ovarian tumour usually has an indolent course.

•

Malignant peritoneal mesothelioma is an aggressive malignancy.

•

The concurrence of both diseases has never been described before in the same woman.

•

We discuss the possible and potential interactions between the two diseases.

KRAS mutation of extraovarian implants of serous borderline tumor: prognostic indicator for adverse clinical outcome

In contrast to non-invasive extraovarian implants, invasive implants of ovarian serous borderline tumor/atypical proliferative serous tumor are associated with adverse outcome and have been reclassified as low-grade serous carcinoma. Mutations of KRAS and/or BRAF have been reported in up to 50% of serous borderline tumor/atypical proliferative serous tumor. We investigated KRAS and BRAF mutation frequencies in the two types of implants of serous borderline tumor/atypical proliferative serous tumor in correlation with clinical outcome. Forty-two implants of serous borderline tumor from 39 patients were included (invasive implants/low-grade serous carcinoma, n=20; non-invasive implants, n=22). KRAS mutation was found in 12 of 20 invasive implants (60%) and 3 of 22 non-invasive implants (14%). BRAF V600E mutation was found in 1 of 22 non-invasive implants (5%) and none in invasive implants (0%). Invasive implants were more frequently associated with higher stage disease. Nine of 14 patients (64%) with KRAS mutation were found to have stage IIIC disease, while 5 of 24 patients (20%) without the mutation had stage IIIC disease. Patients with invasive implants had higher recurrence rate compared to those with non-invasive implants (60 vs 14 %, P=0.0003, log-rank test) and worse disease-specific survival (P=0.0008, log-rank test). Regardless of the histological subtypes, patients with KRAS mutation positive implants had significantly higher recurrence rate than those without the mutation (71 vs 21%, P=0.0021, log-rank test) and an unfavorable disease-specific survival (P=0.0104, log-rank test). In conclusion, compared to those with non-invasive implants, patients with invasive implants present with higher stage of the disease, higher recurrence rate and worse survival. KRAS mutation, but not BRAF V600E mutation, is significantly associated with invasive implants of serous borderline tumor. Regardless of the histological subtypes of the implants, KRAS mutation is a significant prognostic indicator for high risk of tumor recurrence and worse disease-specific survival.

Mutation of NRAS is a rare genetic event in ovarian low-grade serous carcinoma

Activating mutations involving the members of the RAS signaling pathway, including KRAS, NRAS, and BRAF, have been reported in ovarian low-grade serous carcinoma and its precursor lesion, serous borderline tumor (SBT). Whether additional genetic alterations in the RAS oncogene family accumulate during the progression of SBT to invasive low-grade serous carcinoma (LGSC) remains largely unknown. Although mutations of KRAS and BRAF occur at a very early stage of progression, even preceding the development of SBT, additional driving events, such as NRAS mutations, have been postulated to facilitate progression. In this study, we analyzed NRAS exon 3 mutational status in 98 cases that were diagnosed with SBT/atypical proliferative serous tumor, noninvasive LGSC, or invasive LGSC. Of the latter, NRAS Q61R (CAA to CGA) mutations were detected in only 2 of 56 (3.6%) cases. The same mutation was not detected in any of the SBTs (atypical proliferative serous tumors) or noninvasive LGSCs. Mutational analysis for hotspots in KRAS and BRAF demonstrated a wild-type pattern of KRAS and BRAF in one of the NRAS-mutated cases. Interestingly, another LGSC case with NRAS mutation harbored a concurrent BRAF V600L mutation. These findings indicate that, although recurrent NRAS mutations are present, their low prevalence indicates that NRAS plays a limited role in the development of LGSC. Further studies to identify other oncogenic events that drive LGSC progression are warranted.

MR Imaging-Pathologic Correlation in Ovarian Cancer

There are many ovarian cancer subtypes, giving rise to a range of appearances at gross pathology and magnetic resonance (MR) imaging. Certain fundamental concepts at MR, arising from underlying tissue characteristics, can provide guidance to radiologists in suggesting a diagnosis. The ability of multiparametric MR to risk stratify ovarian masses can contribute substantially to clinical decision making and patient management.

Low-grade serous ovarian cancer: A review

Epithelial ovarian cancers can be divided into the more common, aggressive type II cancers and the less common, slow-growing type I cancers. Under this model, serous ovarian carcinomas can be subdivided into high-grade (type II) and low-grade (type I) tumours. The two-tier system for grading serous ovarian carcinomas is superior to more detailed grading systems in terms of predicting survival. Low-grade serous carcinomas typically present in young women and have a relatively good prognosis, despite being resistant to chemotherapy. Low-grade serous cancers have a high prevalence of KRAS and BRAF mutations, but a low prevalence of TP53 mutations (which are characteristic of high-grade serous cancers). Among women with low-grade serous ovarian cancer, the presence of a KRAS/BRAF mutation is a favorable prognostic factor. Studies of the mitogen-activated protein kinase (MAPK) inhibitor in low-grade serous ovarian cancer suggest that identifying MAPK mutations might eventually be useful in guiding treatment.