Low-Pass Genomic Sequencing Reveals Novel Subtypes of Pancreatic Cystic Neoplasms.

BACKGROUND: Over the years, the detection rate of pancreatic cystic neoplasms (PCNs) has significantly increased; however, the differential diagnosis and identification of high-risk PCNs remain challenging. We sought to investigate whether chromosomal instability (CIN) features in cell-free DNA in the cystic fluid of PCNs could help to identify high-risk PCNs. METHODS: Pancreatic cystic fluid samples from 102 patients with PCNs were intraoperatively collected for detection of CIN using an ultrasensitive chromosomal aneuploidy detector. Clinical and imaging data were retrospectively collected, and statistical analysis was performed to assess the potential role of CIN in clinical practice. RESULTS: CIN was investigated in a total of 100 patients. Sixteen of 26 serous cystic cystadenomas (SCAs) harbored deletions of chr3p and/or chr6p, whereas low rates of CIN were detected in mucinous cystic neoplasms. Most malignant PCNs presented with more than one type of CIN; amplification of chr1q and chr8q found in nine and seven of 11 malignant PCNs (81.8% and 63.6%), respectively, could aid in distinguishing high-risk IPMNs from low-risk ones, with a higher sensitivity than imaging. A combination of the mural nodule imaging feature and amplification of chr1q and chr8q achieved a sensitivity of 70.0% and a specificity of 82.4% in identifying high-risk IPMNs. CONCLUSIONS: Our work revealed the distinct CIN signature of different types of PCNs. Deletions of chr3p and chr6p defined a subtype of SCAs. Gains of chr1q and chr8q were associated with insidious malignant PCNs and helped identify high-risk IPMNs.

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.

Interobserver Reproducibility in Assessing Eosinophilic Cells in Ovarian Serous Borderline Tumors to Predict BRAF Mutational Status.

Ovarian serous borderline tumors (SBTs) harboring the BRAFV600E mutation are associated with decreased risk of progression to low-grade serous carcinoma, and often prominently feature tumor cells with abundant eosinophilic cytoplasm. Since eosinophilic cells (ECs) may be a marker of the underlying genetic driver, we proposed morphologic criteria and evaluated the interobserver reproducibility for assessing this histologic feature. Following the completion of an online training module, representative tumor slides from 40 SBTs ( BRAFV600E -mutated, n=18, BRAF -wildtype, n=22) were independently reviewed by 5 pathologists. For each case, reviewers provided a semiquantitative assessment of the extent of ECs (0: absent, 1: <10%, 2: 10%-50%, or 3: >50%, of tumor area). Interobserver reproducibility for estimating the extent of ECs was moderate (κ=0.41). Applying a cut-off score of ≥2, the median sensitivity and specificity for predicting BRAFV600E mutation were 67% and 95%, respectively. With a cut-off score of ≥1, median sensitivity and specificity were 100% and 82%, respectively. Morphologic mimics of ECs, including tumor cells with tufting or hobnail change and detached cell clusters in micropapillary SBTs, were possible contributing factors for discordant interobserver interpretations. BRAFV600E immunohistochemistry showed diffuse staining in BRAF -mutated tumors, including those with few ECs. In conclusion, the finding of extensive ECs in SBT is highly specific for BRAFV600E mutation. However, in some BRAF -mutated SBTs, ECs may be focal and/or difficult to distinguish from other tumor cells with overlapping cytologic features. The morphologic finding of definitive ECs, even when scarce, should therefore prompt consideration for BRAFV 600E mutation testing.

Composite FOXL2 Mutation-positive Adult Granulosa Cell Tumor and Serous Borderline Tumor of the Ovary.

We report a case of a cystic ovarian neoplasm in a 76-yr-old female composed of 2 distinct and intimately associated components: a macrocystic adult granulosa cell tumor (AGCT) and a serous borderline tumor. The granulosa cell nature of the tumor was confirmed with positive immunohistochemical staining for inhibin, calretinin, and WT1, while the neoplastic nature of the granulosa cell proliferation was supported by the presence of a point mutation of the FOXL2 gene. A review of 19 previously reported mixed AGCT and epithelial neoplasms of the ovary is included. Of the eight mixed AGCT and epithelial tumors, including our case, that were tested for FOXL2 mutation, 4 of the 5 mutation-positive cases were notable for demonstrating a macroscopically visible nodule or mass of AGCT at the time of gross examination, while 2 of the 3 mutation-negative cases lacked a mass-producing granulosa cell component. This feature by itself may be sufficient to predict the true neoplastic nature of the granulosa cell proliferation. This is the first reported case of a composite neoplastic AGCT and serous borderline tumor. We also discuss the current histogenetic models for these rare mixed AGCT and epithelial tumors.

Integrating Molecular Analysis into the Pathologic Evaluation of Pancreatic Cysts.

The development of cross-sectional imaging techniques has enhanced the detection of pancreatic cystic lesions (PCLs). PCLs are found in approximately 2% of the general population, often as incidentally detected lesions on computed tomography or MRI during the evaluation of other medical conditions. Broadly, PCLs are classified as mucinous or nonmucinous. Mucinous PCLs include mucinous cystic neoplasms and intraductal papillary mucinous neoplasms. Nonmucinous PCLs include pseudocysts, serous cystadenomas, solid pseudopapillary neoplasms, and cystic pancreatic neuroendocrine tumors, as well as cystic acinar cell carcinoma, cystic degeneration of pancreatic ductal adenocarcinoma, lymphoepithelial cyst, and others.

CD133 Act as an Essential Marker in Ovarian Carcinogenesis.

OBJECTIVE: To analyze the role of cancer stem cells (CSC) in ovarian carcinogenesis through the identification of CD133 expression in the normal ovary (NO), serous cystadenoma (SC), borderline serous tumour (BST), low-grade serous carcinoma (LGSC), and high-grade serous carcinoma (HGSC). MATERIALS AND METHODS: A total of 48 tissue samples contain 5 NO, 10 SC, 5 BST, 8 LGSC, and 20 HGSC were stained with anti-CD133 antibody by immunohistochemical protocol. The difference in the H-score of CD133 expression between groups and their relationship to age, histomorphology, and localization was analyzed. RESULTS: CD133 expression varied among tumor groups, with clinicopathologic parameters showing diverse associations (age p = 0.773; histomorphology p = 0.001; and localization p = 0.026). The comparison of CD133 H-scores differed significantly between each group (p = 0.0031), in which precursor and malignant lesions possessed more robust CD133 expression. CONCLUSION: The presence of CD133 cellular expression and localization in different types of serous ovarian tumours suggests that these markers are involved in ovarian tumorigenesis.

EVI1 overexpression promotes ovarian cancer progression by regulating estrogen signaling.

High-grade serous ovarian cancer (HGSOC) is characterized by TP53 mutation and somatic copy number alterations (SCNAs). Here we show that the oncogenic transcription factor EVI1 (ecotropic viral integration site-1) is amplified and overexpressed up to 30% of 1640 HGSOC cases in The Cancer Genome Atlas (TCGA). Functionally, EVI1 promotes proliferation/invasion in vitro and tumor growth of xenograft model in vivo. Importantly, we discover that EVI1 regulates estrogen signaling by directly activating ESR1 (estrogen receptor 1) transcription determined by the ChIP and luciferase assay. Interestingly, EVI1 and ESR1 share common regulatory targets as indicated by the analysis of ChIP-Seq data. EVI1 and ESR1 collaborate in the regulation of some estrogen receptor-regulated genes. Furthermore, EVI1 drives tumor aggressiveness partially by regulating estrogen signaling. Estrogen enhances the proliferation, invasion and xenograft growth of ovarian cancer cells. Importantly, estrogen can rescue the inhibition of proliferation, invasion and xenograft growth induced by silencing EVI1. These findings suggest that EVI1 functions as a novel regulator of the estrogen signaling network in ovarian cancer.

Identification of Novel Fusion Transcripts in High Grade Serous Ovarian Cancer.

Fusion genes are structural chromosomal rearrangements resulting in the exchange of DNA sequences between genes. This results in the formation of a new combined gene. They have been implicated in carcinogenesis in a number of different cancers, though they have been understudied in high grade serous ovarian cancer. This study used high throughput tools to compare the transcriptome of high grade serous ovarian cancer and normal fallopian tubes in the interest of identifying unique fusion transcripts within each group. Indeed, we found that there were significantly more fusion transcripts in the cancer samples relative to the normal fallopian tubes. Following this, the role of fusion transcripts in chemo-response and overall survival was investigated. This led to the identification of fusion transcripts significantly associated with overall survival. Validation was performed with different analytical platforms and different algorithms to find fusion transcripts.

Identification and Analysis of RNA Editing Events in Ovarian Serous Cystadenoma Using RNA-seq Data.

BACKGROUND: Recent studies have revealed thousands of A-to-I RNA editing events in primates. These events are closely related to the occurrence and development of multiple cancers, but the origination and general functions of these events in ovarian cancer remain incompletely understood. OBJECTIVE: To further the determination of molecular mechanisms of ovarian cancer from the perspective of RNA editing. METHODS: Here, we used the SNP-free RNA editing Identification Toolkit (SPRINT) to detect RNA editing sites. These editing sites were then annotated, and related functional analysis was performed. RESULTS: In this study, about 1.7 million RES were detected in each sample, and 98% of these sites were due to A-to-G editing and were mainly distributed in non-coding regions. More than 1,000 A-- to-G RES were detected in CDS regions, and nearly 700 could lead to amino acid changes. Our results also showed that editing in the 3'UTR regions could influence miRNA-target binding. We predicted the network of changed miRNA-mRNA interaction caused by the A-to-I RNA editing sites. We also screened the differential RNA editing sites between ovarian cancer and adjacent normal tissues. We then performed GO and KEGG pathway enrichment analysis on the genes that contained these differential RNA editing sites. Finally, we identified the potential dysregulated RNA editing events in ovarian cancer samples. CONCLUSION: This study systematically identified and analyzed RNA editing events in ovarian cancer and laid a foundation to explore the regulatory mechanism of RNA editing and its function in ovarian cancer.

Nicotinamide N-methyltransferase overexpression may be associated with poor prognosis in ovarian cancer.

Ovarian cancer is the fifth leading cause of cancer-related mortality in women. Nicotinamide N-methyltransferase (NNMT) is a metabolic enzyme and there is growing evidence to suggest that it plays an important role in cancer progression. This is the first study to examine the expression of NNMT in serous ovarian cystadenomas, serous borderline tumours, low grade serous carcinomas (LGSC) and high grade serous carcinomas (HGSC) and investigate the potential independent association of NNMT expression with survival. Tissue samples were analysed immunohistochemically for NNMT expression. The stromal NNMT score was significantly higher in HGSC compared to serous cystadenomas and serous borderline tumours (p < .001, p < .043, respectively). The mean stromal NNMT score of patients with HGSC was significantly higher than patients with LGSC (p = .043). Patients with low expression of NNMT had a significantly higher mean recurrence-free survival than patients with high expression (p = .036). NNMT may support tumour progression in ovarian cancer by promoting desmoplastic stromal tumour reaction. NNMT overexpression may be associated with poor prognosis and can be a therapeutic target in ovarian cancer.IMPACT STATEMENTWhat is already known on this subject? Nicotinamide N-methyltransferase (NNMT) is a cytosolic enzyme that is overexpressed in many malignancies. Its overexpression was shown to lead to histone hypomethylation, which in turn can decrease and increase the expression of tumour suppressor proteins and onco-proteins, respectively. NNMT was also shown to play a role in epithelial-to-mesenchymal transition, which is critical in tumour progression and the stromal tumour reaction. The stromal tumour reaction was recently targeted with promising therapeutic results in ovarian cancer.What do the results of this study add? The expression of NNMT in various ovarian neoplasms including serous cystadenomas, borderline tumours and serous carcinomas has not been studied and independently associated with poor survival, previously. This study suggests that NNMT is progressively overexpressed in the stroma of ovarian neoplasms from benign cysts to HGSCs. NNMT overexpression appears to be independently associated with poor survival in ovarian cancer.What are the implications of these findings for clinical practice and/or further research? The implications of these findings are that NNMT may play an important role in the stromal tumour reaction, and therefore its overexpression may contribute to poor survival. NNMT overexpression may be an important target of ovarian cancer therapy.

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.

A single-cell landscape of high-grade serous ovarian cancer.

Malignant abdominal fluid (ascites) frequently develops in women with advanced high-grade serous ovarian cancer (HGSOC) and is associated with drug resistance and a poor prognosis1. To comprehensively characterize the HGSOC ascites ecosystem, we used single-cell RNA sequencing to profile ~11,000 cells from 22 ascites specimens from 11 patients with HGSOC. We found significant inter-patient variability in the composition and functional programs of ascites cells, including immunomodulatory fibroblast sub-populations and dichotomous macrophage populations. We found that the previously described immunoreactive and mesenchymal subtypes of HGSOC, which have prognostic implications, reflect the abundance of immune infiltrates and fibroblasts rather than distinct subsets of malignant cells2. Malignant cell variability was partly explained by heterogeneous copy number alteration patterns or expression of a stemness program. Malignant cells shared expression of inflammatory programs that were largely recapitulated in single-cell RNA sequencing of ~35,000 cells from additionally collected samples, including three ascites, two primary HGSOC tumors and three patient ascites-derived xenograft models. Inhibition of the JAK/STAT pathway, which was expressed in both malignant cells and cancer-associated fibroblasts, had potent anti-tumor activity in primary short-term cultures and patient-derived xenograft models. Our work contributes to resolving the HSGOC landscape3-5 and provides a resource for the development of novel therapeutic approaches.

Development and Validation of the Gene Expression Predictor of High-grade Serous Ovarian Carcinoma Molecular SubTYPE (PrOTYPE).

PURPOSE: Gene expression-based molecular subtypes of high-grade serous tubo-ovarian cancer (HGSOC), demonstrated across multiple studies, may provide improved stratification for molecularly targeted trials. However, evaluation of clinical utility has been hindered by nonstandardized methods, which are not applicable in a clinical setting. We sought to generate a clinical grade minimal gene set assay for classification of individual tumor specimens into HGSOC subtypes and confirm previously reported subtype-associated features. EXPERIMENTAL DESIGN: Adopting two independent approaches, we derived and internally validated algorithms for subtype prediction using published gene expression data from 1,650 tumors. We applied resulting models to NanoString data on 3,829 HGSOCs from the Ovarian Tumor Tissue Analysis consortium. We further developed, confirmed, and validated a reduced, minimal gene set predictor, with methods suitable for a single-patient setting. RESULTS: Gene expression data were used to derive the predictor of high-grade serous ovarian carcinoma molecular subtype (PrOTYPE) assay. We established a de facto standard as a consensus of two parallel approaches. PrOTYPE subtypes are significantly associated with age, stage, residual disease, tumor-infiltrating lymphocytes, and outcome. The locked-down clinical grade PrOTYPE test includes a model with 55 genes that predicted gene expression subtype with >95% accuracy that was maintained in all analytic and biological validations. CONCLUSIONS: We validated the PrOTYPE assay following the Institute of Medicine guidelines for the development of omics-based tests. This fully defined and locked-down clinical grade assay will enable trial design with molecular subtype stratification and allow for objective assessment of the predictive value of HGSOC molecular subtypes in precision medicine applications.See related commentary by McMullen et al., p. 5271.

Molecular Diagnosis of Cystic Neoplasms of the Pancreas: a Review.

BACKGROUND: The prevalence of incidental pancreatic cystic neoplasms (PCNs) has increased dramatically with advancements in cross-sectional imaging. Diagnostic imaging is limited in differentiating between benign and malignant PCNs. The aim of this review is to provide an overview of biomarkers that can be used to distinguish PCNs. METHODS: A review of the literature on molecular diagnosis of cystic neoplasms of the pancreas was performed. RESULTS: Pancreatic cysts can be categorized into inflammatory and non-inflammatory lesions. Inflammatory cysts include pancreatic pseudocysts. Noninflammatory lesions include both mucinous and non-mucinous lesions. Mucinous lesions include intraductal papillary mucinous neoplasm (IPMN) and mucinous cystic neoplasm. Non-mucinous lesions include serous cystadenoma and solid-pseudopapillary tumor of the pancreas. Imaging, cyst aspiration, and histologic findings, as well as carcinoembryonic antigen and amylase are commonly used to distinguish between cyst types. However, molecular techniques to detect differences in genetic mutations, protein expression, glycoproteomics, and metabolomic profiling are important developments in distinguishing between cyst types. DISCUSSION: Nomograms incorporating common clinical, laboratory, and imaging findings have been developed in a better effort to predict malignant IPMN. The incorporation of top molecular biomarker candidates to nomograms may improve the predictive ability of current models to more accurately diagnose malignant PCNs.

Intratumoral Heterogeneity Accounts for Apparent Progression of Noninvasive Serous Tumors to Invasive Low-grade Serous Carcinoma: A Study of 30 Low-grade Serous Tumors of the Ovary in 18 Patients With Peritoneal Carcinomatosis.

Noninvasive ovarian low-grade serous tumors [atypical proliferative serous tumor (APST)/serous borderline tumor] appear to progress to invasive low-grade serous carcinoma (LGSC) at a low but regular rate. The underlying biology of this phenomenon is unknown. We studied 18 patients with 30 ovarian tumors (12 bilateral), including APST, noninvasive LGSC and invasive LGSC, who also had low-grade serous carcinomatosis. Tumors were evaluated for microinvasion (usual eosinophilic cell type), microinvasive carcinoma (<5 mm invasion of micropapillary nests), and overt carcinoma (≥5 mm invasion of micropapillary nests). Tumors were evaluated based on the original numerical order of sections under the hypothetical scenarios in which sampling was stopped at 1 section/cm and 2 sections/cm. Sampling based on 1 section/cm of greatest tumor dimension identified invasion of any type in 21 tumors (70%). Among these 21 tumors, 10 had microinvasive carcinoma, and 11 overt carcinoma. Sampling based on 2 sections/cm identified microinvasive carcinoma in 9 tumors and overt carcinoma in 14 tumors. With increased sampling from 1 to 2 sections/cm, the diagnosis in 3 tumors would have changed from microinvasive carcinoma to overt carcinoma, and in an additional 2 tumors from APST to APST with microinvasive carcinoma. Sampling based on >2 sections/cm changed the diagnosis in 1 additional case of APST with microinvasive carcinoma to overt carcinoma. These findings support that undetected (unsampled) occult invasion in the primary ovarian tumors is a likely explanation for some cases of apparent progression of noninvasive low-grade serous ovarian tumors to invasive LGSC. To minimize undetected occult invasion, consideration of sampling noninvasive low-grade ovarian serous tumors with at least 2 sections/cm of maximum tumor diameter may be warranted. The eosinophilic cell type of microinvasion, or microinvasive carcinoma, regardless of size, should prompt further sampling to identify overt carcinoma. The eosinophilic type of microinvasion was never seen alone in this cohort and by itself may be biologically insignificant.

Outcome-Related Differences in Gene Expression Profiles of High-Grade Serous Ovarian Cancers Following Neoadjuvant Chemotherapy.

Large-scale genomic studies have detailed the molecular landscape of tumors from patients with high-grade serous ovarian cancers (HGSC) who underwent primary debulking surgery and correlated the identified subgroups to survival. In recent years, there is increased use of neoadjuvant chemotherapy (NACT) for patients with HGSC and while abundant data exist for patients who underwent primary debulking, little data are available on the cancer cells remaining after NACT that could lead to recurrences. We aimed to analyze gene expression profiles of NACT-treated HGSC tumor samples, and correlate them to treatment response and outcome. Tumor samples were collected from patients with stage III or IV HGSC (NACT cohort, N = 57) at the time of surgery and diagnosis (biopsy samples N = 8). Tumor content was validated by histologic examination and bioinformatics. Gene expression analysis was performed using a tailored NanoString-based assay, while sequencing was performed using MiSeq. A cross-validated survival classifier revealed patient clusters with either a "Better" or "Worse" prognostic outcome. The association with overall survival remained significant after controlling for clinical variables, and differential gene expression, gene set enrichment analyses, and the appropriate survival models were used to assess the associations between alterations in gene expression in cancer cells remaining after NACT and outcome. Pathway-based analysis of the differentially expressed genes revealed comparatively high levels of cell cycle and DNA repair gene expression in the poor outcome group. IMPLICATIONS: Our work suggests mRNA expression patterns in key genes following NACT may reflect response to treatment and outcome in patient with HGSC.

MALDI Mass Spectrometry Imaging of Early- and Late-Stage Serous Ovarian Cancer Tissue Reveals Stage-Specific N-Glycans.

Epithelial ovarian cancer is one of the most fatal gynecological malignancies in adult women. As studies on protein N-glycosylation have extensively reported aberrant patterns in the ovarian cancer tumor microenvironment, obtaining spatial information will uncover tumor-specific N-glycan alterations in ovarian cancer development and progression. matrix-assisted laser desorption/ionization (MALDI) mass spectrometry imaging (MSI) is employed to investigate N-glycan distribution on formalin-fixed paraffin-embedded ovarian cancer tissue sections from early- and late-stage patients. Tumor-specific N-glycans are identified and structurally characterized by porous graphitized carbon-liquid chromatography-electrospray ionization-tandem mass spectrometry (PGC-LC-ESI-MS/MS), and then assigned to high-resolution images obtained from MALDI-MSI. Spatial distribution of 14 N-glycans is obtained by MALDI-MSI and 42 N-glycans (including structural and compositional isomers) identified and structurally characterized by LC-MS. The spatial distribution of oligomannose, complex neutral, bisecting, and sialylated N-glycan families are localized to the tumor regions of late-stage ovarian cancer patients relative to early-stage patients. Potential N-glycan diagnostic markers that emerge include the oligomannose structure, (Hex)6 + (Man)3 (GlcNAc)2 , and the complex neutral structure, (Hex)2 (HexNAc)2 (Deoxyhexose)1 + (Man)3 (GlcNAc)2 . The distribution of these markers is evaluated using a tissue microarray of early- and late-stage patients.

Clinicopathologic and Molecular Features of Paired Cases of Metachronous Ovarian Serous Borderline Tumor and Subsequent Serous Carcinoma.

Although risk factors have been established for the development of serous carcinoma after a diagnosis of serous borderline tumor (SBT), comprising atypical proliferative serous tumor (APST) (ie, conventional SBT) and noninvasive low-grade serous carcinoma (niLGSC) (ie, micropapillary SBT), subsequent invasive carcinoma still occurs in a subset of women who are not at increased risk. Whether subsequent serous carcinoma in women with a prior SBT represents malignant progression/recurrence or an independent primary tumor is unclear, and the combined clinicopathologic and molecular features of SBTs and their subsequent carcinomas have not been fully characterized. In this study, we analyzed a cohort of 42 women initially diagnosed with SBT who subsequently developed serous carcinoma of a total of 1025 cases of ovarian SBT from a nationwide population-based cohort. Review of the diagnostic slides was performed from this subset of SBTs and matched metachronous invasive serous carcinomas (39 low grade, 3 high grade). DNA was extracted from tissue blocks available for 41 cases (both SBT and carcinoma, n=36; SBT only, n=3; carcinoma only, n=2). Samples were subjected to digital droplet PCR to analyze mutation hotspots in KRAS (codon 12) and BRAF (V600E), which are frequently found in low-grade serous tumors. Eighty-one percent of SBTs (34/42) were APST, and 19% (8/42) were niLGSC. Forty percent of cases (17/42) were FIGO stage I, the majority of which were APST (14/17; 82%). The median time to development of carcinoma was 9 years (range, 0.6 to 25 y). Mutations in SBTs were distributed as follows: 5/39 (13%) BRAF mutant, 22/39 (56%) KRAS mutant, and 12/39 (31%) wild-type for both genes. There was a significant relationship between SBT gene mutation and histologic type, with BRAF mutations occurring exclusively in APST and a higher frequency of niLGSC among SBTs wild-type for BRAF and KRAS (P=0.01). The diffuse presence of tumor cells with abundant eosinophilic cytoplasm was significantly associated with the BRAF mutation (P=0.001). Mutational analyses of matched SBT/carcinoma pairs revealed concordant profiles in 33/36 (92%) cases, of which 19 (53%) were KRAS mutant, 4 (11%) were BRAF mutant, and 10 (28%) were wild type for both genes. The 3 discordant cases consisted of a wild-type niLGSC with a subsequent BRAF-mutant invasive LGSC, a KRAS-mutant APST with a KRAS-mutant LGSC, and a BRAF-mutant APST with subsequent development of a KRAS-mutant high-grade serous carcinoma. In conclusion, some women with SBTs can subsequently develop serous carcinoma, occasionally over 10 years later. Most subsequent carcinomas are low grade, but a small subset can be high grade. The type of gene mutation in SBT correlates with various histologic features. While most cases of serous carcinoma developing after a diagnosis of SBT probably represent tumor progression, a minority are independent primary tumors, presumably arising from endosalpingiosis.

Novel Methylated DNA Markers Discriminate Advanced Neoplasia in Pancreatic Cysts: Marker Discovery, Tissue Validation, and Cyst Fluid Testing.

OBJECTIVES: Pancreatic cystic lesions (PCLs) may be precancerous. Those likely to harbor high-grade dysplasia (HGD) or pancreatic cancer (PC) are targets for surgical resection. Current algorithms to predict advanced neoplasia (HGD/PC) in PCLs lack diagnostic accuracy. In pancreatic tissue and cyst fluid (CF) from PCLs, we sought to identify and validate novel methylated DNA markers (MDMs) that discriminate HGD/PC from low-grade dysplasia (LGD) or no dysplasia (ND). METHODS: From an unbiased whole-methylome discovery approach using predefined selection criteria followed by multistep validation on case (HGD or PC) and control (ND or LGD) tissues, we identified discriminant MDMs. Top candidate MDMs were then assayed by quantitative methylation-specific polymerase chain reaction on archival CF from surgically resected PCLs. RESULTS: Of 25 discriminant MDMs identified in tissue, 13 were selected for validation in 134 CF samples (21 cases [8 HGD, 13 PC], 113 controls [45 ND, 68 LGD]). A tree-based algorithm using 2 CF-MDMs (TBX15, BMP3) achieved sensitivity and specificity above 90%. Discrimination was significantly better by this CF-MDM panel than by mutant KRAS or carcinoembryonic antigen, with areas under the receiver operating characteristic curve of 0.93 (95% confidence interval: 0.86-0.99), 0.71 (0.57-0.85), and 0.72 (0.60-0.84), respectively. Cutoffs for the MDM panel applied to an independent CF validation set (31 cases, 56 controls) yielded similarly high discrimination, areas under the receiver operating characteristic curve = 0.86 (95% confidence interval: 0.77-0.94, P = 0.2). DISCUSSION: Novel MDMs discovered and validated in tissue accurately identify PCLs harboring HGD/PC. A panel of 2 MDMs assayed in CF yielded results with potential to enhance current risk prediction algorithms. Prospective studies are indicated to optimize and further evaluate CF-MDMs for clinical use.

Somatic genetic alterations in synchronous and metachronous low-grade serous tumours and high-grade carcinomas of the adnexa.

AIMS: Low-grade serous carcinomas (LGSCs) and their precursors serous borderline tumours (SBTs) characteristically harbour mutations in BRAF, KRAS or NRAS but rarely in TP53, whereas high-grade serous carcinomas (HGSCs) are characterised by frequent TP53 mutations but rare BRAF, KRAS or NRAS mutations. In a small subset of cases, LGSCs and/or SBTs develop into high-grade tumours, including HGSCs and poorly differentiated carcinomas (PDCs). Here, we sought to define the repertoire of somatic genetic alterations in low-grade serous tumours and synchronous or metachronous high-grade adnexal carcinomas. METHODS AND RESULTS: DNA extracted from five SBTs/LGSCs and synchronous or metachronous HGSCs/PDCs and matched normal tissue was subjected to massively parallel sequencing targeting all exons and selected non-coding regions of 341 cancer-related genes. The low-grade and high-grade tumours from a given case were related, and shared mutations and copy number alterations. Progression from low-grade to high-grade lesions was observed, and involved the acquisition of additional mutations and/or copy number alterations, or shifts from subclonal to clonal mutations. Only two (an HGSC and a PDC) of the five high-grade tumours investigated harboured TP53 mutations, whereas NRAS and KRAS hotspot mutations were seen in two HGSCs and one HGSC, respectively. CONCLUSIONS: Our results suggest that progression from SBT to HGSC may take place in a subset of cases, and that at least some of the rare HGSCs lacking TP53 mutations may be derived from a low-grade serous precursor.