Molecular testing for endometrial cancer: An SGO clinical practice statement.

The Cancer Genome Atlas publication first described the genomic landscape of endometrial cancer and characterized these cancers into four molecular subtypes with different prognoses. The Proactive Molecular Classifier for Endometrial Cancer was developed to more easily and inexpensively classify endometrial cancers into four similar molecular subtypes which are termed POLE, mismatch repair deficient, p53 abnormal and no specific molecular profile. Beyond these four subtypes, other molecular biomarkers may influence clinical behavior and response to targeted therapies and include beta-catenin, Her2 amplification, PI3K/mTOR/AKT alterations, L1CAM, hormone receptor expression, tumor mutational burden, and ARID1A. There are numerous clinical trials exploring treatment escalation and de-escalation within the four molecular subtypes as well as matching targeted therapies to specific mutational or biomarker profiles. All endometrial cancers should undergo basic molecular classification that includes assessment of mismatch repair status. POLE and p53 status are prognostic and may become actionable in the future. Clinicians who treat patients with endometrial cancer should understand the role of molecular classification in guiding treatment. The goal of this practice statement is to guide appropriate testing, interpretation, and application of molecular information in endometrial cancer.

A phase 2 study of dasatinib in recurrent clear cell carcinoma of the ovary, fallopian tube, peritoneum or endometrium: NRG oncology/gynecologic oncology group study 0283.

OBJECTIVE: Gynecologic cancers are traditionally managed according to their presumed site of origin, without regard to the underlying histologic subtype. Clear cell histology is associated with chemotherapy refractoriness and poor survival. Mutations in SWI/SNF chromatin remodeling complex member ARID1A, which encodes for BAF250a protein, are common in clear cell and endometriosis-associated endometrioid carcinomas. High-throughput cell-based drug screening predicted activity of dasatinib, a tyrosine kinase inhibitor, in ARID1A-mutant clear cell carcinoma. METHODS: We conducted a phase 2 clinical trial of dasatinib 140 mg once daily by mouth in patients with recurrent or persistent ovarian and endometrial clear cell carcinoma. Patients with measurable disease were enrolled and then assigned to biomarker-defined populations based on BAF250a immunohistochemistry. The translational endpoints included broad next-generation sequencing to assess concordance of protein expression and treatment outcomes. RESULTS: Twenty-eight patients, 15 of whom had tumors with retained BAF250a and 13 with loss of BAF250a were evaluable for treatment response and safety. The most common grade 3 adverse events were anemia, fatigue, dyspnea, hyponatremia, pleural effusion, and vomiting. One patient had a partial response, eight (28%) had stable disease, and 15 (53.6%) had disease progression. Twenty-three patients had next-generation sequencing results; 13 had a pathogenic ARID1A alteration. PIK3CA mutations were more prevalent in ARID1A-mutant tumors, while TP53 mutations were more prevalent in ARID1A wild-type tumors. CONCLUSIONS: Dasatinib was not an effective single-agent treatment for recurrent or persistent ovarian and endometrial clear cell carcinoma. Studies are urgently needed for this rare gynecologic subtype.

The role of CTNNB1 mutations and matrix metalloproteinases (MMPs) in anti-angiogenesis treatment of endometrial carcinoma.

OBJECTIVE: Treatment options and associated biomarkers for advanced and recurrent disease are limited. Endometrial cancers (ECs) with CTNNB1 exon 3 mutations appear to have preferential response to bevacizumab, an anti-angiogenesis treatment, though the mechanism of action is unknown. We aim to identify mediators of bevacizumab-responsive endometrial cancers. METHODS: We analyzed RNA expression from TCGA and protein expression from CPTAC to identify likely targets for ß-catenin overactivity. We then transiently and stably overexpressed ß-catenin in EC cells to confirm the results suggested by our in silico analysis. We performed corroborative experiments by silencing CTNNB1 in mutated cell lines to demonstrate functional specificity. We implanted transduced cells into xenograft models to study microvessel density. RESULTS: CTNNB1-mutated ECs were associated with increased ß-catenin and MMP7 protein abundance (P < 0.001), but not VEGF-A protein abundance. Overexpressing ß-catenin in EC cells did not increase VEGF-A abundance but did increase expression and secretion of MMP7 (P < 0.03). Silencing CTNNB1 in CTNNB1-mutated cells decreased MMP7 gene expression in EC (P < 0.0001). Microvessel density was not increased. CONCLUSIONS: These data provide a mechanistic understanding for bevacizumab-response in CTNNB1-mutated ECs demonstrated in GOG-86P. We hypothesize that overexpressed and secreted MMP7 potentially digests VEGFR-1, releasing VEGF-A, and increasing its availability. These activities may drive the formation of permeable vessels, which contributes to tumor progression, metastasis, and immune suppression. This mechanism is unique to EC and advocates for further clinical trials evaluating this treatment-related biomarker.

Genetic and molecular subtype heterogeneity in newly diagnosed early- and advanced-stage endometrial cancer.

OBJECTIVE: To characterize and compare the molecular subtypes and profiles of prospectively-accrued newly-diagnosed early- and advanced-stage endometrial cancers (ECs). METHODS: EC patients consented to an IRB-approved protocol of massively parallel sequencing of 410-468 cancer-related genes; 175 ECs of 7 histologic types (n = 135 FIGO stages I/II, n = 40 FIGO stages III/IV) were included. Previously reported sequencing data from 99 additional advanced-stage ECs were retrieved for comparisons. RESULTS: Irrespective of histologic type, all 175 ECs could be stratified into the molecular subtypes, with 75 (43%) being of p53 wild-type, 49 (28%) MMR-deficient, 39 (22%) p53 abnormal and 12 (7%) of POLE molecular subtypes. Subtype distribution, mutational and copy number profiles varied according to histologic type. In endometrioid ECs, genetic alterations varied according to histologic grade. Potential therapeutic targets, including high tumor mutational burden, ERBB2 amplification and PIK3CA hotspot mutations, were found across histologic types in 63% (n = 110) of all ECs. Compared to their early-stage counterparts, advanced-stage endometrioid ECs had a significantly higher fraction of genome altered (median 0.1% vs 12%, p < 0.001) and ARID1B mutations (0% vs 11%, p = 0.01), and advanced-stage serous ECs harbored more frequent ERBB2 amplification (18% vs 8%, p > 0.05) and PIK3CA mutations (46% vs 27%, p > 0.05). Whole-genome doubling was found in advanced- but not early-stage carcinosarcomas and clear cell carcinomas. CONCLUSIONS: Our findings demonstrate the molecular heterogeneity within and across histologic types of EC and the increased genomic complexity of advanced-stage ECs. Molecular subtypes are present across EC histologic types and may help stratify EC patients for prognostic and therapeutic purposes.

Clinical outcomes of patients with endometrioid epithelial ovarian cancer following surgical treatment.

BACKGROUND: Endometrioid epithelial ovarian cancer (EEOC) is rare, and its management poorly defined. We examined factors associated with 5-year progression-free survival (PFS) after surgery for EEOC. METHODS: Retrospective study: treatment and outcomes of all EEOC patients undergoing initial surgery at, or presenting to, our institution within 3 months of initial surgery, 1/2002-9/2017. RESULTS: In total, 212 patients were identified. Median follow-up, 63.9 months (range, 0.7-192); median age at diagnosis, 52 years (range, 20-88); disease stage: I, n = 145 (68%); II, n = 47 (22%); III/IV, n = 20 (9%); FIGO grade: 1, 127 (60%); 2, 66 (31%); 3, 17 (8%); unknown, 2 (1%). One hundred twenty-eight (60%) had endometriosis; 75 (35%), synchronous endometrioid endometrial cancer (80%, IA); 101 (48%), complete surgical staging; 8 (5%), positive pelvic lymph nodes (LNs); 6 (4%), positive para-aortic LNs; 176 (97%), complete gross resection; 123 (60%), postoperative chemotherapy; 56(28%), no additional treatment. Five-year PFS, 83% (95% confidence interval [CI]: 76.6%-87.8%); 5-year overall survival (OS), 92.7% (95% CI: 87.7%-95.8%). Age, stage, and surgical staging were associated with improved 5-year PFS, and younger age at diagnosis with improved 5-year OS (p < 0.001). Chemotherapy did not improve 5-year PFS in IA/IB versus observation, but improved survival in IC (hazard ratio [HR]: 1.01, 95% CI: 0.22-4.59, p = 0.99; HR: 0.17, 95% CI: 0.04-0.7, p = 0.006). CONCLUSIONS: Age, stage, and full surgical staging were associated with improved 5-year PFS. Chemotherapy showed no benefit in IA/IB disease.

Fumarate hydratase FH c.1431_1433dupAAA (p.Lys477dup) variant is not associated with cancer including renal cell carcinoma.

Fumarate hydratase (FH) mutations underpin the autosomal recessive syndrome. FH deficiency and the autosomal dominant syndrome hereditary leiomyomatosis and renal cell carcinoma (HLRCC). The FH c.1431_1433dupAAA (p.Lys477dup) genomic alteration has been conclusively shown to contribute to FH deficiency when occurring with another FH germline alteration. However, a sufficiently large dataset has been lacking to conclusively determine its clinical significance to cancer predisposition in the heterozygous state. We reviewed a series of 7,571 patients with cancer who received germline results through MSK-IMPACT testing at the Memorial Sloan Kettering Cancer Center. The FH c.1431_1433dupAAA (p.Lys477dup) variant was detected in 24 individuals, none of whom was affected with renal cancer. Eleven of the 372 patients with renal cancer were identified to carried pathogenic FH variants associated with HLRCC. None of these 372 patients with renal cancer carried the FH c.1431_1433dupAAA variant. Our data indicate the FH c.1431_1433dupAAA is not associated with cancer including renal cell carcinoma.

Genomic profiling of primary and recurrent adult granulosa cell tumors of the ovary.

Adult-type granulosa cell tumor (aGCT) is a rare malignant ovarian sex cord-stromal tumor, harboring recurrent FOXL2 c.C402G/p.C134W hotspot mutations in 97% of cases. These tumors are considered to have a favorable prognosis, however aGCTs have a tendency for local spread and late recurrences, which are associated with poor survival rates. We sought to determine the genetic alterations associated with aGCT disease progression. We subjected primary non-recurrent aGCTs (n = 7), primary aGCTs that subsequently recurred (n = 9) and their matched recurrences (n = 9), and aGCT recurrences without matched primary tumors (n = 10) to targeted massively parallel sequencing of ≥410 cancer-related genes. In addition, three primary non-recurrent aGCTs and nine aGCT recurrences were subjected to FOXL2 and TERT promoter Sanger sequencing analysis. All aGCTs harbored the FOXL2 C134W hotspot mutation. TERT promoter mutations were found to be significantly more frequent in recurrent (18/28, 64%) than primary aGCTs (5/19, 26%, p = 0.017). In addition, mutations affecting TP53, MED12, and TET2 were restricted to aGCT recurrences. Pathway annotation of altered genes demonstrated that aGCT recurrences displayed an enrichment for genetic alterations affecting cell cycle pathway-related genes. Analysis of paired primary and recurrent aGCTs revealed that TERT promoter mutations were either present in both primary tumors and matched recurrences or were restricted to the recurrence and absent in the respective primary aGCT. Clonal composition analysis of these paired samples further revealed that aGCTs display intra-tumor genetic heterogeneity and harbor multiple clones at diagnosis and relapse. We observed that in a subset of cases, recurrences acquired additional genetic alterations not present in primary aGCTs, including TERT, MED12, and TP53 mutations and CDKN2A/B homozygous deletions. Albeit harboring relatively simple genomes, our data provide evidence to suggest that aGCTs are genetically heterogeneous tumors and that TERT promoter mutations and/or genetic alterations affecting other cell cycle-related genes may be associated with disease progression and recurrences.

Clinical outcomes of patients with POLE mutated endometrioid endometrial cancer.

OBJECTIVES: Assess outcomes of a clinical cohort of patients with endometrioid endometrial cancer (EEC) harboring somatic POLE exonuclease domain mutations (EDMs). METHODS: Patients were consented to a protocol of tumor-normal massively parallel sequencing of 410-468 cancer related genes. EECs subjected to sequencing from 2014 to 2018 were reviewed. Tumors with somatic POLE EDMs were identified. EECs were assessed for microsatellite instability (MSI) using MSIsensor and immunohistochemical analysis for mismatch repair (MMR) proteins. RESULTS: Of the 451 EECs sequenced, 23 had a POLE EDM (5%): 20 primary and 3 recurrent tumors sequenced. Nineteen cases (83%) were stage I/II and 4 (17%) were stages III/IV. Thirteen EECs (57%) were of FIGO grades 1/2, 10 (43%) grade 3. All patients were treated with surgery and 17 (89%) received adjuvant therapy. Five (22%) demonstrated loss of DNA MMR protein expression, none were due to Lynch syndrome. MSIsensor scores were conclusive for 21 samples: 19 were microsatellite stable and 2 MSI-high. After median follow-up of 30 months, 4/23 (17%) developed recurrences: 3 with initial grade 3 stage I and 1 with grade 1 stage III disease. One patient with grade 2 stage IV EEC had progressive disease after treatment. CONCLUSIONS: Patients with POLE EDM EEC have been shown to have a favorable prognosis. In this real-world cohort of patients, de novo metastatic disease and recurrences in initially uterine-confined cases were observed. Further research is warranted before incorporating the presence of POLE EDM into decision-making regarding adjuvant therapy.

Molecular profiling and molecular classification of endometrioid ovarian carcinomas.

OBJECTIVE: Endometrioid ovarian carcinomas (EOCs) comprise 5-10% of all ovarian cancers and commonly co-occur with synchronous endometrioid endometrial cancer (EEC). We sought to examine the molecular characteristics of pure EOCs in patients without concomitant EEC. METHODS: EOCs and matched normal samples were subjected to massively parallel sequencing targeting 341-468 cancer-related genes (n = 8) or whole-genome sequencing (n = 28). Mutational frequencies of EOCs were compared to those of high-grade serous ovarian cancers (HGSOCs; n = 224) and EECs (n = 186) from The Cancer Genome Atlas, and synchronous EOCs (n = 23). RESULTS: EOCs were heterogeneous, frequently harboring KRAS, PIK3CA, PTEN, CTNNB1, ARID1A and TP53 mutations. EOCs were distinct from HGSOCs at the mutational level, less frequently harboring TP53 but more frequently displaying KRAS, PIK3CA, PIK3R1, PTEN and CTNNB1 mutations. Compared to synchronous EOCs and pure EECs, pure EOCs less frequently harbored PTEN, PIK3R1 and ARID1A mutations. Akin to EECs, EOCs could be stratified into the four molecular subtypes: 3% POLE (ultramutated), 19% MSI (hypermutated), 17% copy-number high (serous-like) and 61% copy-number low (endometrioid). In addition to microsatellite instability, a subset of EOCs harbored potentially targetable mutations, including AKT1 and ERBB2 hotspot mutations. EOCs of MSI (hypermutated) subtype uniformly displayed a good outcome. CONCLUSIONS: EOCs are heterogeneous at the genomic level and harbor targetable genetic alterations. Despite the similarities in the repertoire of somatic mutations between pure EOCs, synchronous EOCs and EECs, the frequencies of mutations affecting known driver genes differ. Further studies are required to define the impact of the molecular subtypes on the outcome and treatment of EOC patients.

Morphologic Features of Gastric-type Cervical Adenocarcinoma in Small Surgical and Cytology Specimens.

Gastric-type cervical adenocarcinoma (GCA) is a human papillomavirus-unassociated, aggressive, chemorefractory tumor. Well-differentiated examples may exhibit bland morphologic appearances, which could potentially lead to misdiagnosis, particularly in limited material. We sought to characterize the morphologic features of GCA in surgical biopsy and cytology specimens. We identified patients with histologic diagnoses of GCA or minimal-deviation adenocarcinoma between 2004 and 2017. Available slides from biopsy, curettage, and cytology specimens were reviewed. Fifty-nine specimens (37 histology, 22 cytology) were reviewed from 23 patients, including histology specimens alone from 6 patients, cytology specimens alone from 4 patients, and both types of specimen from 13 patients. The median patient age was 52 yr (range, 29-83 yr). Biopsies showed well-to-moderately differentiated adenocarcinomas composed of cells with pale or foamy cytoplasm and well-defined cytoplasmic borders. Nuclei exhibited mild-to-moderate pleomorphism with small nucleoli. The diagnosis was challenging in a minority of biopsies in which neoplastic glandular epithelium was scant, fragmented, and/or well differentiated. Cytology slides showed single and crowded clusters of tumor cells with pale, foamy, and/or vacuolated cytoplasm and well-defined cytoplasmic borders. Nuclei were moderately pleomorphic, round to oval with one or more nucleoli. Of 20 submitted biopsies, GCA was suspected by the submitting pathologist in only 5 (25%) cases. Awareness of the morphologic features and use of confirmatory ancillary studies (eg, immunohistochemistry for markers of gastric differentiation and human papillomavirus testing) will allow accurate diagnosis of these aggressive tumors in biopsy and cytology specimens.

ZC3H7B-BCOR high-grade endometrial stromal sarcomas: a report of 17 cases of a newly defined entity.

High-grade endometrial stromal sarcoma likely encompasses underrecognized tumors harboring genetic abnormalities besides YWHAE-NUTM2 fusion. Triggered by three initial endometrial stromal sarcomas with ZC3H7B-BCOR fusion characterized by high-grade morphology and aggressive clinical behavior, we herein investigate the clinicopathologic features of this genetic subset by expanding the analysis to 17 such tumors. All of them occurred in adult women with a median age of 54 (range, 28-71) years. They were predominantly based in the endomyometrium and demonstrated tongue-like and/or pushing myometrial invasion. Most were uniformly cellular and displayed haphazard fascicles of spindle cells with mild to moderate nuclear atypia. Myxoid matrix was seen in 14 of 17 (82%) tumors, and collagen plaques were seen in 8 (47%). The mitotic index was ≥10 mitotic figures/10 high-power fields (HPFs) in 14 of 17 (82%) tumors with a median of 14.5 mitotic figures/10 HPFs. No foci of conventional or variant low-grade endometrial stromal sarcoma were seen. All tumors expressed CD10 with only limited or absent desmin, SMA and/or h-caldesmon staining. ER and PR expression in >5% of cells was seen in 4 of 12 (33%) tumors. Diffuse cyclin D1 and BCOR immunoreactivity was present in 7 of 8 (88%) and 7 of 14 (50%) tumors, respectively. Fluorescence in situ hybridization or targeted RNA sequencing confirmed ZC3H7B-BCOR fusion in all tumors, including four and two previously diagnosed as myxoid leiomyosarcoma and undifferentiated uterine sarcoma, respectively. Limited clinical data suggest that patients present at higher stage and have worse prognosis compared with published outcomes in low-grade endometrial stromal sarcoma. Tumors with ZC3H7B-BCOR fusion constitute a distinct group of endometrial stromal sarcomas with high-grade morphology that should be distinguished from other uterine mesenchymal neoplasms that may demonstrate myxoid morphology.

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 BRAFV600E (26, 34%), KRASG12D (eight, 11%), and KRASG12V (eight, 11%). BRAFV600E 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 BRAFV600E -mutated tumours and correlated with BRAF mutation-associated histological features (P < 0.0001). CONCLUSIONS: BRAFV600E mutations are significantly more common in SBTs than in LGSCs. Immunohistochemical expression of VE1 protein is associated strongly with BRAFV600E mutation and BRAF mutation-associated histological features. VE1 immunohistochemistry is a reliable method for the detection of BRAFV600E mutations.

Massively parallel sequencing analysis of mucinous ovarian carcinomas: genomic profiling and differential diagnoses.

OBJECTIVE: Mucinous ovarian cancer (MOC) is a rare type of epithelial ovarian cancer resistant to standard chemotherapy regimens. We sought to characterize the repertoire of somatic mutations in MOCs and to define the contribution of massively parallel sequencing to the classification of tumors diagnosed as primary MOCs. METHODS: Following gynecologic pathology and chart review, DNA samples obtained from primary MOCs and matched normal tissues/blood were subjected to whole-exome (n = 9) or massively parallel sequencing targeting 341 cancer genes (n = 15). Immunohistochemical analysis of estrogen receptor, progesterone receptor, PTEN, ARID1A/BAF250a, and the DNA mismatch (MMR) proteins MSH6 and PMS2 was performed for all cases. Mutational frequencies of MOCs were compared to those of high-grade serous ovarian cancers (HGSOCs) and mucinous tumors from other sites. RESULTS: MOCs were heterogeneous at the genetic level, frequently harboring TP53 (75%) mutations, KRAS (71%) mutations and/or CDKN2A/B homozygous deletions/mutations (33%). Although established criteria for diagnosis were employed, four cases harbored mutational and immunohistochemical profiles similar to those of endometrioid carcinomas, and one case for colorectal or endometrioid carcinoma. Significant differences in the frequencies of KRAS, TP53, CDKN2A, FBXW7, PIK3CA and/or APC mutations between the confirmed primary MOCs (n = 19) and HGSOCs, mucinous gastric and/or mucinous colorectal carcinomas were found, whereas no differences in the 341 genes studied between MOCs and mucinous pancreatic carcinomas were identified. CONCLUSIONS: Our findings suggest that the assessment of mutations affecting TP53, KRAS, PIK3CA, ARID1A and POLE, and DNA MMR protein expression may be used to further aid the diagnosis and treatment decision-making of primary MOC.

Evolving Roles of Histologic Evaluation and Molecular/Genomic Profiling in the Management of Endometrial Cancer.

Endometrial cancers are the most common gynecologic malignancies. The staging of endometrial cancer has evolved from a clinical-based system to a comprehensive surgical-pathologic approach that allows for better risk stratification and treatment planning. Over the past few years, use of NCCN's sentinel lymph node (SLN) mapping algorithm for the surgical staging of endometrial cancer has gained significant acceptance and is now commonly applied in many practices. However, pathologic evaluation of prognostic factors is beset by challenges, including the reproducibility of histologic classification and FIGO's grading, as well as the questionable clinical significance of low-volume tumor in SLNs. With the revelation of major genomic classes of endometrial cancer comes the potential for improved, reproducible, and prognostically relevant classification schemes, which integrate traditional pathologic parameters with genomic findings, to aid in treatment decisions. Pathologic identification of new variants of endometrial cancer, such as undifferentiated carcinoma, continues to advance the phenotypic spectrum of these tumors, spurring genomic and functional studies to further characterize their mechanistic underpinnings and potentially reveal new avenues for treatment. In the era of precision medicine, pathologic assessment of biomarkers (eg, mismatch repair proteins) and recognition of phenotypes that are amenable to specific targeted therapies (such as POLE-mutated tumors) have become integral to the management of women with endometrial carcinoma.

The genetic landscape of endometrial clear cell carcinomas.

Clear cell carcinoma of the endometrium is a rare type of endometrial cancer that is generally associated with an aggressive clinical behaviour. Here, we sought to define the repertoire of somatic genetic alterations in endometrial clear cell carcinomas (ECCs), and whether ECCs could be classified into the molecular subtypes described for endometrial endometrioid and serous carcinomas. We performed a rigorous histopathological review, immunohistochemical analysis and massively parallel sequencing targeting 300 cancer-related genes of 32 pure ECCs. Eleven (34%), seven (22%) and six (19%) ECCs showed abnormal expression patterns for p53, ARID1A, and at least one DNA mismatch repair (MMR) protein, respectively. Targeted sequencing data were obtained from 30 of the 32 ECCs included in this study, and these revealed that two ECCs (7%) were ultramutated and harboured mutations affecting the exonuclease domain of POLE. In POLE wild-type ECCs, TP53 (46%), PIK3CA (36%), PPP2R1A (36%), FBXW7 (25%), ARID1A (21%), PIK3R1 (18%) and SPOP (18%) were the genes most commonly affected by mutations; 18% and 11% harboured CCNE1 and ERBB2 amplifications, respectively, and 11% showed DAXX homozygous deletions. ECCs less frequently harboured mutations affecting CTNNB1 and PTEN but more frequently harboured PPP2R1A and TP53 mutations than non-POLE endometrioid carcinomas from The Cancer Genome Atlas (TCGA). Compared to endometrial serous carcinomas (TCGA), ECCs less frequently harboured TP53 mutations. When a surrogate model for the molecular-based TCGA classification was used, all molecular subtypes previously identified in endometrial endometrioid and serous carcinomas were present in the ECCs studied, including POLE, MMR-deficient, copy-number high (serous-like)/p53 abnormal, and copy-number low (endometrioid)/p53 wild-type, which were significantly associated with disease-free survival in univariate analysis. These findings demonstrate that ECCs constitute a histologically and genetically heterogeneous group of tumours with varying outcomes. Furthermore, our data suggest that the classification of ECCs as being generally 'high-grade' or 'type II' tumours may not be warranted. Copyright © 2017 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.

Frequent Mismatch Repair Protein Deficiency in Mixed Endometrioid and Clear Cell Carcinoma of the Endometrium.

Mixed endometrioid and clear cell carcinoma of the endometrium refers to a scenario in which the tumor exhibits histologic features of both endometrioid and clear cell carcinoma. We observed a tendency for these tumors to occur in a mismatch repair (MMR) protein-deficient molecular background in a prior study that examined a small cohort of mixed-type endometrial carcinomas. The aim of this study was to determine the rate of MMR protein deficiency in a larger series of endometrial mixed endometrioid and clear cell carcinomas, through a retrospective survey of MLH1, PMS2, MSH2, and MSH6 expression in such tumors at 5 tertiary centers. A total of 41 cases were identified and 27 (66%) tumors demonstrated MMR protein deficiency with a comparable frequency across the contributing centers (ranging from 56% to 83%). Among the MMR protein-deficient cases, 59% showed concurrent MLH1 and PMS2 loss, 33% showed concurrent MSH2 and MSH6 loss, and 4% showed isolated PMS2 or MSH6 loss. Compared with a previously published series of 15 pure endometrial clear cell carcinomas, mixed endometrioid and clear cell carcinomas are associated with significantly better disease-specific survival (P=0.02). In summary, endometrial carcinomas with mixed endometrioid and clear cell histology are frequently MMR protein deficient. This finding has implications both for our understanding of its tumor biology and for the identification of patients with potential Lynch syndrome.

Mixed Mesonephric Adenocarcinoma and High-grade Neuroendocrine Carcinoma of the Uterine Cervix: Case Description of a Previously Unreported Entity With Insights Into Its Molecular Pathogenesis.

Human papillomavirus (HPV)-negative cervical carcinomas are uncommon and typically encompass unusual histologic subtypes. Mesonephric adenocarcinoma is one such subtype. Mesonephric tumors in the female genital tract are thought to arise from Wolffian remnants, and are extremely rare tumors with widely variable morphology. Sarcomatoid dedifferentiation has been previously described in a few cases, but other forms of dedifferentiation have not been reported. Neuroendocrine carcinoma of the cervix (e.g. small cell carcinoma) is associated with HPV infection, typically HPV 18. These tumors often arise in association with a conventional epithelial component such as squamous cell carcinoma or usual-type endocervical adenocarcinoma. We describe a case of mesonephric adenocarcinoma of the uterine cervix associated with an HPV-negative high-grade neuroendocrine carcinoma at the morphologic and immunophenotypic level, for which we performed targeted massively parallel sequencing analysis of the 2 elements. Both components shared identical mutations in U2AF1 p.R156H (c.467G>A) and GATA3 p.M422fs (c.1263dupG), as well as MYCN amplification. In addition, the neuroendocrine carcinoma harbored TP53 and MST1R mutations not present in the mesonephric carcinoma. Our data suggest a clonal origin of the 2 components of this rare entity, rather than a collision tumor.

Comparison of metastatic neuroendocrine neoplasms to the breast and primary invasive mammary carcinomas with neuroendocrine differentiation.

Metastatic neuroendocrine neoplasms to the breast may show considerable morphologic overlap with primary mammary carcinomas, particularly those showing evidence of neuroendocrine differentiation, and may be misdiagnosed as such. Accurate distinction between these two entities is crucial for determination of appropriate clinical management. The histologic and immunohistochemical features of metastatic neuroendocrine neoplasms to the breast were studied and compared with the features of primary invasive mammary carcinomas with neuroendocrine differentiation, which served as controls. Of the metastatic neuroendocrine neoplasms, 15 were well-differentiated neuroendocrine tumors with carcinoid tumor-type morphology and 7 were poorly differentiated/high-grade neuroendocrine carcinomas with small-cell or large-cell neuroendocrine carcinoma morphology. The majority of the metastatic neoplasms originated in the lung and gastrointestinal tract. There were histologic similarities between metastatic neuroendocrine neoplasms and invasive mammary carcinomas with neuroendocrine differentiation, both of which exhibited neuroendocrine histologic features (nested and trabecular architecture, minimal tubular differentiation, and characteristic nuclear features). Only one case of the invasive mammary carcinomas with neuroendocrine differentiation was modified Bloom-Richardson grade 1 (largely due to minimal tubular differentiation on most such tumors), and the invasive mammary carcinomas with neuroendocrine differentiation were often associated with in situ carcinoma. Immunohistochemistry was helpful in distinguishing metastatic neuroendocrine neoplasms from invasive mammary carcinomas with neuroendocrine differentiation. Whereas the majority of invasive mammary carcinomas with neuroendocrine differentiation were positive for estrogen receptor and GATA3, metastatic neuroendocrine neoplasms were typically negative for estrogen receptor and GATA3, and metastatic well-differentiated neuroendocrine tumors often showed immunoreactivity for site-specific markers. Although the histologic and immunohistochemical features of a breast tumor may raise the suspicion of a metastatic neuroendocrine neoplasm, the pathologic findings should be interpreted in the context of the clinical history and imaging findings in order to establish an accurate diagnosis.

Endometrial Carcinomas With Clear Cells: A Study of a Heterogeneous Group of Tumors Including Interobserver Variability, Mutation Analysis, and Immunohistochemistry With HNF-1ß.

Endometrial clear cell carcinoma (CC) is an uncommon tumor and often carries a poor prognosis. It has histologic features that overlap with other endometrial carcinomas and is frequently misclassified. Accurate classification is crucial, however, to improve treatment options. The objectives of this study were (1) to assess diagnostic interobserver variability among 5 gynecologic pathologists for tumors originally diagnosed as CC or with a component of CC (n=44); (2) to determine the utility of immunohistochemical markers estrogen receptor and HNF-1ß; and (3) to detect mutations in select genes. Clinical data and morphologic features were also recorded. Agreement among reviewers was only moderate: only 46% of the original CC remained classified as such. After reclassification, estrogen receptor was positive in 8% of CC, 67% of endometrioid carcinomas (EC), and 47% of serous carcinomas (SC). Sensitivities of HNF-1ß in CC, SC, and EC were 62%, 27%, and 17%, respectively, whereas specificity for CC versus EC or SC was 78%. Mutations in PIK3CA, PIK3R1, PTEN, KRAS, and NRAS were detected in 41% of 37 cases that had adequate material for study. At least 1 mutation was identified in 33% of CC, 67% of EC, and 33% of SC. This group of patients had poor outcomes: 72% of the patients with follow-up information had died of disease. In summary, this study suggests that the current pool of CC is a heterogeneous group of tumors from the morphologic, immunophenotypic, and molecular point of views and that only a percentage of them represent true CC.

Bevacizumab shows activity in patients with low-grade serous ovarian and primary peritoneal cancer.

OBJECTIVE: Low-grade serous (LGS) ovarian and primary peritoneal cancer is a rare disease with limited therapeutic options. Low response rates are observed with cytotoxic chemotherapy. However, significant responses have been reported in patients treated with bevacizumab. The objective of this study was to determine the response rate to bevacizumab with or without concurrent chemotherapy in patients with recurrent serous borderline or LGS ovarian or primary peritoneal cancer. METHODS: This single-institution retrospective study examined the response rate to treatment with bevacizumab in patients with serous borderline or LGS cancer. Patients were treated at the Memorial Sloan Kettering Cancer Center between 2005 and 2012. The best overall response was determined with the use of the Response Evaluation Criteria in Solid Tumors. RESULTS: A total of 17 patients were identified, 15 of whom were evaluable for the primary end point of best overall response. Two patients were treated with bevacizumab as a single agent, and the remainder received bevacizumab in conjunction with chemotherapy (paclitaxel, topotecan, oral cyclophosphamide, gemcitabine, or gemcitabine and carboplatin). The median duration of bevacizumab administration in evaluable patients was 23 weeks (mean, 32.2 weeks; range, 6-79.4 weeks). There were no complete responses. Partial responses were observed in 6 patients (5 patients received concurrent paclitaxel, and 1 patient received concurrent gemcitabine). The overall response rate was 40%, with a response rate of 55% among the subgroup of patients with LGS cancer. CONCLUSIONS: These results indicate that bevacizumab in combination with chemotherapy is an active treatment for recurrent LGS ovarian cancer. A prospective trial of bevacizumab in combination with paclitaxel for the treatment of LGS ovarian cancer should be considered.