Comparison of mutations of Ki-RAS and p53 immunoreactivity in borderline and malignant epithelial ovarian tumors

Amplification of Hippo Signaling Pathway Genes Is Governed and Implicated in the Serous Subtype-Specific Ovarian Carcino-Genesis

Among women, ovarian cancer ranks as the fifth most common cause of cancer-related deaths. This study examined the impact of Hippo signaling pathway on ovarian carcinogenesis. Therefore, the signatures related to Hippo signaling pathway were derived from the molecular signatures database (MSigDB) and were used for further analysis. The Z score-based pathway activation scoring method was employed to investigate the expression patterns of these signatures in the mRNA expression profiles of ovarian cancer cohorts. Compared to other subtype tumors, the results of this study show that the Hippo signaling pathway signatures are dysregulated prominently in serous subtype-specific ovarian carcinogenesis. A receiver operating characteristic (ROC) curve-based results of the Hippo gene set, yes-associated protein 1 (YAP1), and mammalian sterile 20-like kinases 1 (MST1) genes can predict the serous subtype tumors by higher specificity and sensitivity with significant areas under the curve values also further reconfirmed these signaling dysregulations. Moreover, these gene sets were studied further for mutation analysis in the profile of high-grade serous ovarian adenocarcinoma in the cBioPortal database. The OncoPrint results reveal that these Hippo signaling pathway genes are amplified highly during the grade three and stage third or fourth of serous type ovarian tumors. In addition, the results of the Dependency Map (DepMap) plot also clearly show that these genes are amplified significantly across the ovarian cancer cell lines. Finally, overall survival (OS) curve plot investigations also revealed that these gene expressions show poor survival patterns linked to highly expressed conditions in serous subtypes of ovarian cancer patients with significant p-values (p < 0.05). Thus, the current finding would help to develop the targeted therapies treatment for serous subtype ovarian carcinogenesis.

Role of RAS signaling in ovarian cancer

The RAS family of proteins is among the most frequently mutated genes in human malignancies. In ovarian cancer (OC), the most lethal gynecological malignancy, RAS, especially KRAS mutational status at codons 12, 13, and 61, ranges from 6-65% spanning different histo-types. Normally RAS regulates several signaling pathways involved in a myriad of cellular signaling cascades mediating numerous cellular processes like cell proliferation, differentiation, invasion, and death. Aberrant activation of RAS leads to uncontrolled induction of several downstream signaling pathways such as RAF-1/MAPK (mitogen-activated protein kinase), PI3K phosphoinositide-3 kinase (PI3K)/AKT, RalGEFs, Rac/Rho, BRAF (v-Raf murine sarcoma viral oncogene homolog B), MEK1 (mitogen-activated protein kinase kinase 1), ERK (extracellular signal-regulated kinase), PKB (protein kinase B) and PKC (protein kinase C) involved in cell proliferation as well as maintenance pathways thereby driving tumorigenesis and cancer cell propagation. KRAS mutation is also known to be a biomarker for poor outcome and chemoresistance in OC. As a malignancy with several histotypes showing varying histopathological characteristics, we focus on reviewing recent literature showcasing the involvement of oncogenic RAS in mediating carcinogenesis and chemoresistance in OC and its subtypes.

KRAS Mutation in Endometriosis-Associated Ovarian Borderline and Malignant Epithelial Tumors

Background: Endometriosis is a common disease among women with the capacity to transform into ovarian neoplasms. KRAS mutation is a keystone in tumor-genesis of many malignant neoplasms. Objectives: In the current study, we investigated KRAS mutations in endometriosis-associated ovarian borderline and malignant epithelial tumors. Methods: The specimens of 42 consecutive patients undergoing a surgical procedure whose final diagnosis comprised endometriosis-associated borderline and malignant epithelial ovarian tumors including 12 borderline epithelial tumors and 30 ovarian epithelial carcinomas were histopathologically reviewed. All cases were evaluated regarding the type of tumor, differentiation and simultaneous presence of endometriosis or atypical endometriosis. DNA extraction from the selected paraffin block was done and mutation of codons 12 and 13 was assessed. Results: Due to the quality of genomic DNA for PCR study was not acceptable in 6 out of 42 cases, among remaining 36 cases, KRAS mutation was observed in 6 cases including 2 cases with mutations in 2nd base of 12th codon (G→T), 3 cases with substitution of G→A in the 2nd base of 12th codon, and one with substitution of G→T in the 1st base of 12th codon. Conclusions: We evaluated the KRAS mutation in the spectrum of ovarian epithelial tumors associated with endometriosis for treatment approaches including targeted therapies. Our results suggested a possible link between KRAS mutation and endometriosis-associated ovarian borderline and malignant tumors but there was no convincing evidence to prove a definite linkage.

Progression of Cystadenoma to Mucinous Borderline Ovarian Tumor in Young Females: Case Series and Literature Review

STUDY OBJECTIVE

To study the progression of benign ovarian lesions to mucinous borderline ovarian tumors (mBOTs); analyze the clinicopathologic features, diagnosis, and management of mBOTs in pediatric and adolescent girls; and provide a review of the literature on mBOTs in this population.

DESIGN

Retrospective chart review of female adolescents younger than 18 years diagnosed with mBOTs between July 2017 and February 2021.

SETTING

Yale New Haven Hospital, New Haven, Connecticut; and Yale New Haven Health Bridgeport Hospital, Bridgeport, Connecticut.

PARTICIPANTS

Three female patients diagnosed with mBOTs between ages 12 and 17 years.

INTERVENTIONS

None.

MAIN OUTCOME MEASURES

Clinical presentation, preoperative characteristics, surgical technique, histology, tumor stage, treatment, progression, outcome, and rate of recurrence.

RESULTS

Three adolescent patients were identified to have mBOTs. All three patients presented with a chief complaint of abdominal pain. One of the 3 patients was premenarchal at presentation. Two of the 3 patients were initially diagnosed with a mucinous cystadenoma and had recurrences of an ovarian cyst in the same ovary within 5 and 17 months, respectively. Pathology of the recurrent cyst was consistent with mBOT. Two of the 3 patients initially underwent cystectomy, and all ultimately had a unilateral salpingo-oophorectomy. Subsequent surveillance over 2 to 4 years found no evidence of disease recurrence.

CONCLUSION

mBOTs are rare in the pediatric and adolescent population and could arise from benign ovarian tumors.

Clinicopathologic Features and Risk Factors for Recurrence of Mucinous Borderline Ovarian Tumors: A Retrospective Study With Follow-up of More Than 10 Years

OBJECTIVE

This study aimed to evaluate the clinicopathologic features of mucinous borderline ovarian tumors (MBOTs), with an emphasis on the risk factors for recurrence.

METHODS

Data of 76 patients with MBOT diagnosed and treated between 2000 and 2007 at a single institution were analyzed in this retrospective study. The clinicopathologic features of different tumor subgroups were analyzed, including pathology, surgical methodology, recurrence, and overall survival.

RESULTS

The median patient age was 40 years (13-85 years). Forty-six patients with gastrointestinal mucinous borderline tumors (intestinal MBOTs) (73.7%) and 20 patients with endocervical MBOT (26.3%) were identified. Forty radical surgeries and 26 conservative surgeries were performed. There were 74.6% patients (50/67) with stage I disease among the 67 patients who received comprehensive surgical staging.During a median follow-up time of 151 months, 9 recurrences were identified. Median duration from surgery to recurrence was 26.4 months (range, 13-50 months). There was no difference in recurrence rate between intestinal MBOT and endocervical MBOT (14.3% vs 5.0%; P > 0.05). The recurrence rate of stage III tumors was significantly higher than that of stage I (33.3% vs 8%; P < 0.05). The recurrence rate after conservative surgery was higher than that after radical procedures (21.4% vs 6.3%; P < 0.05).

CONCLUSIONS

The majority of patients with MBOT had a favorable prognosis. Patients with later-stage disease had a higher recurrence rate.

Distinct methylation profile of mucinous ovarian carcinoma reveals susceptibility to proteasome inhibitors

Mucinous type of epithelial ovarian cancer (MuOC) is a unique subtype with a poor survival outcome in recurrent and advanced stages. The role of type-specific epigenomics and its clinical significance remains uncertain. We analyzed the methylomic profiles of 6 benign mucinous adenomas, 24 MuOCs, 103 serous type of epithelial ovarian cancers (SeOCs) and 337 nonepithelial ovarian cancers. MuOC and SeOC exhibited distinct DNA methylation profiles comprising 101 genes, 81 of which exhibited low methylation in MuOC and were associated with the response to glucocorticoid, ATP hydrolysis-coupled proton transport, proteolysis involved in the cellular protein catabolic process and ion transmembrane transport. Hierarchical clustering analysis showed that the profiles of MuOC were similar to colorectal adenocarcinoma and stomach adenocarcinoma. Genetic interaction network analysis of differentially methylated genes in MuOC showed a dominant network module is the proteasome subunit beta (PSMB) family. Combined functional module and methylation analysis identified PSMB8 as a candidate marker for MuOC. Immunohistochemical staining of PSMB8 used to validate in 94 samples of ovarian tumors (mucinous adenoma, MuOC or SeOC) and 62 samples of gastrointestinal cancer. PSMB8 was commonly expressed in MuOC and gastrointestinal cancer samples, predominantly as strong cytoplasmic and occasionally weak nuclei staining, but was not expressed in SeOC samples. Carfilzomib, a second-generation proteasome inhibitor, suppressed MuOC cell growth in vitro. This study unveiled a mucinous-type-specific methylation profile and suggests the potential use of a proteasome inhibitor to treat MuOC.

The Putative Role of TP53 Alterations and p53 Expression in Borderline Ovarian Tumors - Correlation with Clinicopathological Features and Prognosis: A Mini-Review

Borderline ovarian tumors (BOTs) represent an independent group among ovarian malignancies, being diagnosed at clinical stage earlier than invasive ovarian carcinomas (OCs) and characterized by a rather favorable outcome after careful surgical management. Data published worldwide showed a substantial discordance of p53 expression in BOTs. The purpose of this work was to present the current status of knowledge on the significance of TP53 gene and p53 protein product alterations in BOTs. In general, higher p53 expression patterns were reported for ovarian malignancies compared to BOTs. Serous, mucinous, and endometrioid BOTs differ substantially in relation to p53 immunostaining, but data concerning the relationship between the protein's immunoreactivity and other clinico-pathological variables are scarce. Finally, reports published to date support the view that TP53 alterations may not be commonly associated with the borderline phenotype of ovarian tumors but they probably occur during the development of invasive OCs. In light of these uncertainties, the impact of TP53 alterations and p53 expression on overall survival in women affected by BOTs requires further multi-institutional studies in large cohorts of patients.

Subtypes of Ovarian Cancer and Ovarian Cancer Screening

Ovarian cancer is the foremost cause of gynecological cancer death in the developed world, as it is usually diagnosed at an advanced stage. In this paper we discuss current issues, the efficacy and problems associated with ovarian cancer screening, and compare the characteristics of ovarian cancer subtypes. There are two types of ovarian cancer: Type I carcinomas, which are slow-growing, indolent neoplasms thought to arise from a precursor lesion, which are relatively common in Asia; and Type II carcinomas, which are clinically aggressive neoplasms that can develop de novo from serous tubal intraepithelial carcinomas (STIC) and/or ovarian surface epithelium and are common in Europe and the USA. One of the most famous studies on the subject reported that annual screening using CA125/transvaginal sonography (TVS) did not reduce the ovarian cancer mortality rate in the USA. In contrast, a recent study in the UK showed an overall average mortality reduction of 20% in the screening group. Another two studies further reported that the screening was associated with decreased stage at detection. Theoretically, annual screening using CA125/TVS could easily detect precursor lesions and could be more effective in Asia than in Europe and the USA. The detection of Type II ovarian carcinoma at an early stage remains an unresolved issue. The resolving power of CA125 or TVS screening alone is unlikely to be successful at resolving STICs. Biomarkers for the early detection of Type II carcinomas such as STICs need to be developed.

Recent concepts of ovarian carcinogenesis: type I and type II

Type I ovarian tumors, where precursor lesions in the ovary have clearly been described, include endometrioid, clear cell, mucinous, low grade serous, and transitional cell carcinomas, while type II tumors, where such lesions have not been described clearly and tumors may develop de novo from the tubal and/or ovarian surface epithelium, comprise high grade serous carcinomas, undifferentiated carcinomas, and carcinosarcomas. The carcinogenesis of endometrioid and clear cell carcinoma (CCC) arising from endometriotic cysts is significantly influenced by the free iron concentration, which is associated with cancer development through the induction of persistent oxidative stress. A subset of mucinous carcinomas develop in association with ovarian teratomas; however, the majority of these tumors do not harbor any teratomatous component. Other theories of their origin include mucinous metaplasia of surface epithelial inclusions, endometriosis, and Brenner tumors. Low grade serous carcinomas are thought to evolve in a stepwise fashion from benign serous cystadenoma to a serous borderline tumor (SBT). With regard to high grade serous carcinoma, the serous tubal intraepithelial carcinomas (STICs) of the junction of the fallopian tube epithelium with the mesothelium of the tubal serosa, termed the “tubal peritoneal junction” (TPJ), undergo malignant transformation due to their location, and metastasize to the nearby ovary and surrounding pelvic peritoneum. Other theories of their origin include the ovarian hilum cells.

Precursors and pathogenesis of ovarian carcinoma

The ultimate goal of defining cancer specific precursors is to facilitate early detection and intervention before the development of invasive malignancy. Unlike other malignancies involving the female genital tract such as cervical or endometrial carcinomas, precursor lesions of ovarian carcinomas have not been well characterised, resulting in a failure to develop effective screening programs. Recent clinicopathological and molecular studies have provided new insight into the origin and pathogenesis of ovarian carcinomas. It has been shown that ovarian cancer is comprised of different tumour types differing not only in morphology, but also in pathogenesis, molecular alterations and clinical progression. A dualistic model of ovarian carcinogenesis has been proposed. Type I tumours which include low grade serous, low grade endometrioid, clear cell, mucinous carcinomas and Brenner tumours, are generally indolent and tend to be genetically stable, although clear cell carcinoma would probably belong to an intermediate category. They demonstrate a step-wise progression from a benign precursor such as a benign to borderline tumour or endometriosis and are characterised by genetic aberrations targeting specific cell signalling pathways. Type II tumours comprise high grade serous, high grade endometrioid, and undifferentiated carcinomas as well as malignant mixed mesodermal tumours. They are clinically aggressive and exhibit high genetic instability with frequent p53 mutations. Mounting evidence suggests that many high grade serous carcinomas originate from the epithelium of the distal fallopian tube, and that serous tubal intraepithelial carcinoma (STIC) represents the putative precursor of these neoplasms. Low grade serous carcinomas arise via transformation of benign and borderline serous tumours, thought to be derived from inclusion cysts originating from the ovarian surface or tubal epithelium. Recently it has been suggested that papillary tubal hyperplasia may be a putative precursor lesion for serous borderline tumours. Both endometrioid and clear cell carcinomas develop from endometriosis, via alterations affecting different genetic pathways. The origin of mucinous and transitional cell neoplasms is not well characterised, although new data suggest a possible origin from transitional cell nests present at the tubal-mesothelial junction. Likewise, the pathogenesis of carcinosarcomas is also not well established because of their rarity but there is accumulating evidence that the carcinomatous component determines the course of the disease and gives rise to the malignant mesenchymal component. This review discusses recent developments in the pathogenesis of ovarian carcinoma, with particular emphasis on the putative precursor lesions that give rise to the major histological subtypes. Recognition of these lesions is not only important in improving the understanding of ovarian carcinogenesis, but it will also influence our approach to prevent, detect and treat these tumours.

Clinicopathological correlates and prognostic significance of KRAS mutation status in a pooled prospective cohort of epithelial ovarian cancer

Background

Activating KRAS mutations are common in ovarian carcinomas of low histological grade, less advanced clinical stage and mucinous histological subtype, and form part of the distinct molecular alterations associated with type I tumors in the dualistic model of ovarian carcinogenesis. Here, we investigated the occurrence, clinicopathological correlates and prognostic significance of specific KRAS mutations in tumours from 153 epithelial ovarian cancer (EOC) cases from a pooled, prospective cohort.

Methods

KRAS codon 12,13 and 61 mutations were analysed by pyrosequencing in tumours from 163 incident EOC cases in the Malmö Diet and Cancer Study and Malmö Preventive Project. Associations of mutational status with clinicopathological and molecular characteristics were assessed by Pearson Chi Square test. Ovarian cancer-specific survival (OCSS) according to mutational status was explored by Kaplan-Meier analysis and Cox proportional hazards modelling. KRAS-mutation status was also analysed in 28 concomitantly sampled benign-appearing fallopian tubes.

Results

Seventeen (11.1%) EOC cases harboured mutations in the KRAS gene, all but one in codon 12, and one in codon 13. No KRAS mutations were found in codon 61 and all examined fallopian tubes were KRAS wild-type. KRAS mutation was significantly associated with lower grade (p = 0.001), mucinous histological subtype (p = < 0.001) and progesterone receptor expression (p = 0.035). Kaplan-Meier analysis revealed a significantly improved OCSS for patients with KRAS-mutated compared to KRAS wild-type tumours (p = 0.015). These associations were confirmed in unadjusted Cox regression analysis (HR = 2.51; 95% CI 1.17-5.42) but did not remain significant after adjustment for age, grade and clinical stage. The beneficial prognostic impact of KRAS mutation was ony evident in tumours of low-intermediate differentiation grade (p = 0.023), and in a less advanced clinical stage (p = 0.014). Moreover, KRAS mutation was associated with a significantly improved OCSS in the subgroup of endometroid carcinomas (p = 0.012).

Conclusions

The results from this study confirm previously demonstrated associations of KRAS mutations with well-differentiated and mucinous ovarian carcinomas. Moreover, KRAS-mutated tumours had a significantly improved survival in unadjusted, but not adjusted, analysis. A finding that merits further study is the significant prognostic impact of KRAS mutation in endometroid carcinomas, potentially indicating that response to Ras/Raf/MEK/ERK-targeting therapies may differ by histological subtype.

Virtual slides

The virtual slide(s) for this article can be found here: http://www.diagnosticpathology.diagnomx.eu/vs/1788330379100147

Frequency of mutations and polymorphisms in borderline ovarian tumors of known cancer genes

Borderline ovarian tumors represent an understudied subset of ovarian tumors. Most studies investigating aberrations in borderline tumors have focused on KRAS/BRAF mutations. In this study, we conducted an extensive analysis of mutations and single-nucleotide polymorphisms (SNPs) in borderline ovarian tumors. Using the Sequenom MassArray platform, we investigated 160 mutations/polymorphisms in 33 genes involved in cell signaling, apoptosis, angiogenesis, cell cycle regulation and cellular senescence. Of 52 tumors analyzed, 33 were serous, 18 mucinous and 1 endometrioid. KRAS c.35G>A p.Gly12Asp mutations were detected in eight tumors (six serous and two mucinous), BRAF V600E mutations in two serous tumors, and PIK3CA H1047Y and PIK3CA E542K mutations in a serous and an endometrioid BOT, respectively. CTNNB1 mutation was detected in a serous tumor. Potentially functional polymorphisms were found in vascular endothelial growth factor (VEGF), ABCB1, FGFR2 and PHLPP2. VEGF polymorphisms were the most common and detected at four loci. PHLPP2 polymorphisms were more frequent in mucinous as compared with serous tumors (P=0.04), with allelic imbalance in one case. This study represents the largest and most comprehensive analysis of mutations and functional SNPs in borderline ovarian tumors to date. At least 25% of borderline ovarian tumors harbor somatic mutations associated with potential response to targeted therapeutics.

Proposal for Creating a Guideline for Cancer Registration of Microinvasive Tumors of the Breast and Ovary (II)

BACKGROUND

Cancer registration in Korea has a longer than 30-years of history, during which time cancer registration has improved and become well-organized. Cancer registries are fundamental for cancer control and multi-center collaborative research. However, there have been discrepancies in assigning behavior codes. Thus, we intend to propose appropriate behavior codes for the International Classification of Disease Oncology, 3rd edition (ICD-O-3) for microinvasive tumors of the ovary and breast not only to improve the quality of the cancer registry but also to prevent conflicts.

METHODS

As in series I, two pathology study groups and the Cancer Registration Committee of the Korean Society of Pathologists (KSP) participated. To prepare a questionnaire on provisional behavior code, the relevant subjects were discussed in the workshop, and consensus was obtained by convergence of opinion from members of KSP.

RESULTS

Microinvasive tumor of the breast should be designated as a microinvasive carcinoma which was proposed as malignant tumor (/3). Serous borderline tumor with microinvasion of the ovary was proposed as borderline tumor (/1), and mucinous borderline tumor with microinvasion of the ovary as either borderline (/1) or carcinoma (/3) according to the tumor cell nature.

CONCLUSIONS

Some issues should be elucidated with the accumulation of more experience and knowledge. Here, however, we present our second proposal.

Borderline ovarian tumour: pathological diagnostic dilemma and risk factors for invasive or lethal recurrence

By comparison with ovarian carcinomas, borderline ovarian tumours are characterised clinically by superior overall survival, even in women with peritoneal spread. In this Review, we aimed to clarify the histological and clinical factors potentially defining a high-risk group in whom disease is likely to evolve to invasive disease. Invasive peritoneal implants (in serous borderline ovarian tumours) and residual disease after surgery were the two factors clearly identified. Other factors are controversial owing to increased risk of invasive recurrence: micropapillary patterns in serous borderline ovarian tumour, intraepithelial carcinoma in mucinous lesions, stromal microinvasion in serous lesions, and use of cystectomy in mucinous borderline ovarian tumours. The pathologist has a pivotal role in assessment of the borderline nature of ovarian tumours and in identification of high-risk criteria, most of which are histological. But, reproducibility of the histological interpretation of some of these potential criteria--eg, classification of peritoneal implants (particularly in desmoplastic subtype), stromal microinvasion, micropapillary patterns, and intraepithelial carcinoma in mucinous borderline ovarian tumours--remains unclear, and should be investigated.

"Piling up" clear cells in müllerian-type mucinous and mixed cell-type borderline tumor do not represent concomitant clear cell neoplasms

The nature of "piling up" proliferation of clear cells in müllerian mucinous/mixed borderline tumor has not been well characterized. The purpose of this study was to clarify whether or not such clear cells represent concomitant clear cell neoplasms. First, we carefully reviewed hematoxylin and eosin slides taken from 139 ovarian tumors diagnosed as clear cell carcinoma (112 cases) and müllerian mucinous/mixed borderline tumor (27 cases) to clarify (1) the frequency of piling-up clear cells in müllerian mucinous/mixed borderline tumor and (2) the frequency of the coexistence of typical clear cell carcinoma and müllerian mucinous/mixed borderline tumor. Second, we investigated the immunohistochemical expression of estrogen receptor, hepatocyte nuclear factor-1β, and glypican-3 in proliferating clear cells in both tumors. We identified piling-up clear cells in 56% of müllerian mucinous/mixed borderline tumors. Such clear cells lacked the severe nuclear atypia, complex branching, and dense hyalinized cores of typical clear cell carcinoma. We did not find coexistence of typical clear cell carcinoma and müllerian mucinous/mixed borderline tumor in any tumors. Piling-up clear cells and endocervical-like mucinous cells were positive for estrogen receptor but negative for hepatocyte nuclear factor-1β and glypican-3. Most clear cell carcinomas showed a hepatocyte nuclear factor-1β-positive/estrogen receptor-negative immunophenotype, and about half of them were glypican-3 positive. In conclusion, piling-up clear cells in müllerian mucinous/mixed borderline tumor do not represent concomitant clear cell neoplasms because clear cell carcinoma and müllerian mucinous/mixed borderline tumor hardly ever coexist and because such clear cells in both tumors are immunophenotypically distinct.

KRAS mutations in ovarian low-grade endometrioid adenocarcinoma: association with concurrent endometriosis

The association between ovarian endometrioid adenocarcinoma and endometriosis is well established. However, not all endometrioid adenocarcinomas are directly related to endometriosis, and it has been suggested that there may be clinicopathologic differences between endometriosis-positive and endometriosis-negative tumors. Molecular alterations in endometrioid adenocarcinoma include KRAS and BRAF mutations, but the incidence of these abnormalities in previous reports has been highly variable (0%-36% and 0%-24%, respectively). This may be explained by relatively small sample sizes in earlier studies but could also reflect difficulties in accurately classifying high-grade ovarian malignancies. In the current study, we investigated KRAS and BRAF mutations in 78 low-grade (FIGO grade 1 and 2) endometrioid adenocarcinomas and compared the results with the presence of endometriosis in the tumor-associated ovary and/or in other pelvic sites. KRAS mutations were identified in 12 (29%) of 42 endometriosis-associated endometrioid adenocarcinomas with satisfactory analysis but in only 1 (3%) of 29 tumors in which endometriosis was not identified. BRAF mutation was identified only in a single endometriosis-associated case. These findings support the hypothesis that endometriosis-associated and independent endometrioid adenocarcinoma may develop via different molecular pathways and that KRAS mutations have an important role only in the former tumors. In contrast, BRAF mutations do not appear to have a significant role in either endometrioid adenocarcinoma subgroup. This may be relevant to future targeted therapies in patients with high-stage or recurrent disease and indicate that histopathologists should carefully examine endometrioid adenocarcinoma specimens, including nonneoplastic tissues, for the presence of endometriosis.

Benign and Low Grade Serous Epithelial Tumors: Recent Developments and Diagnostic Problems

This review focuses on recent advances in the area of low-grade ovarian serous neoplasia with emphasis on key diagnostic criteria, differential diagnosis, and disease classification based on current understanding of low-grade serous carcinogenesis. Despite considerable controversy surrounding serous tumors of low malignant potential (S-LMP) or borderline tumors, there have been great strides in our understanding of the serous group of borderline and malignant pelvic epithelial neoplasms in the past decade. Most S-LMP have a favorable prognosis, but recurrences and progression to carcinoma occur, sometimes following a protracted clinical course. Pathologic risk factors vary, but the extraovarian implant status is the most important predictor for progressive disease. Progression of S-LMP usually takes the form of low-grade serous carcinoma, although transformation to high-grade carcinoma is occasionally seen. A pelvic S-LMP - low-grade serous carcinoma pathway has been proposed based on global gene expression profiling, shared mutations in KRAS and/or BRAF, and in most cases, the presence of S-LMP in de novo low-grade serous carcinoma. Unlike high-grade serous carcinoma, low-grade serous carcinoma responds poorly to standard platinum-based chemotherapy. Development of more tailored therapy for S-LMP with invasive implants and low-grade serous carcinoma, ideally based on a relative risk model for disease progression, is under active clinical investigation.

KRAS mutation analysis in genomic DNA isolated from formalin-fixed paraffin-embedded ovarian tissue: evaluation of a strip-based reverse-hybridisation assay

AIMS

To evaluate a reverse-hybridisation assay (strip assay) designed for the sensitive detection of 10 mutations in codons 12 and 13 of the KRAS gene. The strip assay relies on mutant-enriched PCR followed by reverse-hybridisation of biotinylated amplification products to oligonucleotide probes immobilised as an array of parallel lines on nitrocellulose test strips.

METHODS

The strip assay was used to analyse genomic DNA isolated from 120 formalin-fixed paraffin-embedded (FFPE) ovarian tissue samples. The samples were analysed in parallel using a biochip-based protocol (biochip assay) covering the same mutation spectrum, and results were compared with respect to sensitivity, specificity and operational input.

RESULTS

The strip assay identified 19 (16%) of 120 FFPE samples to carry a KRAS mutation; results were in agreement with those obtained by biochip hybridisation. Both assays had an analytical sensitivity of 1% when performed on FFPE-extracted DNA with approximately the same operational input needed for post-PCR processing. In contrast to the biochip assay, strip assay hybridisation may be automated to a large extent.

CONCLUSIONS

The strip assay is an accurate and sensitive tool for the low to medium throughput detection of KRAS mutation in genomic DNA isolated from FFPE tissue.

Development of an ovarian cancer screening decision model that incorporates disease heterogeneity: implications for potential mortality reduction

BACKGROUND

Pathologic and genetic data suggest that epithelial ovarian cancer may consist of indolent and aggressive phenotypes. The objective of the current study was to estimate the impact of a 2-phenotype paradigm of epithelial ovarian cancer on the mortality reduction achievable using available screening technologies.

METHODS

The authors modified a Markov model of ovarian cancer natural history (the 1-phenotype model) to incorporate aggressive and indolent phenotypes (the 2-phenotype model) based on histopathologic criteria. Stage distribution, incidence, and mortality were calibrated to data from the Surveillance, Epidemiology, and End Results Program of the US National Cancer Institute. For validation, a Monte Carlo microsimulation (1000,000 events) of the United Kingdom Collaborative Trial of Ovarian Cancer Screening (UKCTOCS) multimodality prevalence screen was performed. Mortality reduction and positive predictive value (PPV) were estimated for annual screening.

RESULTS

In validation against UKCTOCS data, the model-predicted percentage of screen-detected cancers diagnosed at stage I and II was 41% compared with 47% (UKCTOCS data), and the model-predicted PPV of screening was 27% compared with 35% (UKCTOCS data). The model-estimated PPV of a strategy of annual population-based screening in the United States at ages 50 to 85 years was 14%. The mortality reduction using annual postmenopausal screening was 14.7% (1-phenotype model) and 10.9% (2-phenotype model). Mortality reduction was lower with the 2-phenotype model than with the 1-phenotype model regardless of screening frequency or test sensitivity; 68% of cancer deaths are accounted for by the aggressive phenotype.

CONCLUSIONS

The current analysis suggested that reductions in ovarian cancer mortality using available screening technologies on an annual basis are likely to be modest. A model that incorporated 2 clinical phenotypes of ovarian carcinoma into its natural history predicted an even smaller potential reduction in mortality because of the more frequent diagnosis of indolent cancers at early stages.

Characterization of the molecular differences between ovarian endometrioid carcinoma and ovarian serous carcinoma

The histopathological diagnosis of high-grade endometrioid and serous carcinoma of the ovary is poorly reproducible under the current morphology based classification system, especially for anaplastic, high-grade tumours. The transcription factor Wilms' tumour-1 (WT1) is differentially expressed among the gynaecological epithelia from which epithelial ovarian cancers (EOCs) are believed to originate. In EOCs, WT1 protein is observed in the majority of serous carcinomas and in up to 30% of endometrioid carcinomas. It is unclear whether the latter is a reflection of the actual incidence of WT1 protein expression in endometrioid carcinomas, or whether a significant number of high-grade serous carcinomas have been misclassified as endometrioid carcinoma. Several genetic aberrations are reported to occur in EOCs. These include mutation of the TP53 gene, aberrant activation of beta-catenin signalling and loss of PTEN protein expression, among others. It is unclear whether these aberrations are histotype-specific. The aim of this study was to better define the molecular characteristics of serous and endometrioid carcinomas in an attempt to address the problems with the current histopathological classification methods. Gene expression profiles were analysed to identify reproducible gene expression phenotypes for endometrioid and serous carcinomas. Tissue microarrays (TMA) were used to assess the incidence of TP53, beta-catenin and PTEN aberrations in order to correlate their occurrence with WT1 as an immunohistochemistry based biomarker of serous histotype. It was found that nuclear WT1 protein expression can identify misclassified high-grade endometrioid carcinomas and these tumours should be reassigned to serous histotype. Although low-grade endometrioid carcinomas rarely progress to high-grade carcinomas, a combined WT1-negative, TP53-positive immunophenotype may identify an uncommon high-grade subtype of ovarian endometrioid carcinoma. GEO database: array data accession number GSE6008.

Genomic aberrations in borderline ovarian tumors

Background

According to the scientific literature, less than 30 borderline ovarian tumors have been karyotyped and less than 100 analyzed for genomic imbalances by CGH.

Methods

We report a series of borderline ovarian tumors (n = 23) analyzed by G-banding and karyotyping as well as high resolution CGH; in addition, the tumors were analyzed for microsatellite stability status and by FISH for possible 6q deletion.

Results

All informative tumors were microsatellite stable and none had a deletion in 6q27. All cases with an abnormal karyotype had simple chromosomal aberrations with +7 and +12 as the most common. In three tumors with single structural rearrangements, a common breakpoint in 3q13 was detected. The major copy number changes detected in the borderline tumors were gains from chromosome arms 2q, 6q, 8q, 9p, and 13q and losses from 1p, 12q, 14q, 15q, 16p, 17p, 17q, 19p, 19q, and 22q. The series included five pairs of bilateral tumors and, in two of these pairs, informative data were obtained as to their clonal relationship. In both pairs, similarities were found between the tumors from the right and left side, strongly indicating that bilaterality had occurred via a metastatic process. The bilateral tumors as a group showed more aberrations than did the unilateral ones, consistent with the view that bilaterality is a sign of more advanced disease.

Conclusion

Because some of the imbalances found in borderline ovarian tumors seem to be similar to imbalances already known from the more extensively studied overt ovarian carcinomas, we speculate that the subset of borderline tumors with detectable imbalances or karyotypic aberrations may contain a smaller subset of tumors with a tendency to develop a more malignant phenotype. The group of borderline tumors with no imbalances would, in this line of thinking, have less or no propensity for clonal evolution and development to full-blown carcinomas.

Ovarian cancer pathogenesis: a model in evolution

Ovarian cancer is a deadly disease for which there is no effective means of early detection. Ovarian carcinomas comprise a diverse group of neoplasms, exhibiting a wide range of morphological characteristics, clinical manifestations, genetic alterations, and tumor behaviors. This high degree of heterogeneity presents a major clinical challenge in both diagnosing and treating ovarian cancer. Furthermore, the early events leading to ovarian carcinoma development are poorly understood, thus complicating efforts to develop screening modalities for this disease. Here, we provide an overview of the current models of ovarian cancer pathogenesis, highlighting recent findings implicating the fallopian tube fimbria as a possible site of origin of ovarian carcinomas. The ovarian cancer model will continue to evolve as we learn more about the genetics and etiology of this disease.

KRAS mutation analysis in ovarian samples using a high sensitivity biochip assay

Background

Mutations in the KRAS gene are one of the most frequent genetic abnormalities in ovarian carcinoma. They are of renewed interest as new epidermal growth factor receptor (EGFR)-targeted therapies are being investigated for use in ovarian carcinoma. As KRAS mutations are associated with poor response and resistance to EGFR-targeting drugs, this study was conducted to obtain more information on the spectrum of KRAS mutations in ovarian carcinoma.

Methods

The presence of KRAS mutations in codon 12 and 13 was analyzed in frozen and formalin-fixed paraffin-embedded (FFPE) tissue with a low density biochip platform. 381 malignant (29 borderline malignancy, 270 primary carcinomas, and 82 recurrent carcinomas) and 22 benign tissue samples from a total of 394 patients were examined. KRAS mutational status of each sample was correlated with dignity, FIGO stage, grade, histology, and survival.

Results

KRAS mutations were found in 60 (15%) samples with 58 samples deriving from malignant tissue and 2 samples deriving from benign tissue. In 55 (92%) samples codon 12 was found to be mutated. Frozen and FFPE samples concurred with respect to KRAS mutation status.

Conclusion

KRAS mutation is a common event in ovarian cancer primarily in carcinomas of lower grade, lower FIGO stage, and mucinous histotype. The KRAS mutational status is no prognostic factor for patients treated with standard therapy. However, in line with experience from colorectal cancer and non-small-cell-lung cancer (NSCLC), it may be important for prediction of response to EGFR-targeted therapies.

Pathogenesis of ovarian cancer: lessons from morphology and molecular biology and their clinical implications

The accepted view of ovarian carcinogenesis is that carcinoma begins in the ovary, undergoes progressive "dedifferentiation" from a well to a poorly differentiated tumor, and then spreads to the pelvic and abdominal cavities before metastasizing to distant sites. It has therefore been reasoned that survival for this highly lethal disease could be improved by developing screening methods that detect disease when it is confined to the ovary. To date, however, no prospective randomized trial of any ovarian cancer screening test(s) has demonstrated a decrease in mortality. We believe that one of the main reasons for this is that the dogma underlying ovarian carcinogenesis is flawed. Based on studies performed in our laboratory during the last decade, we have proposed a model of ovarian carcinogenesis that takes into account the diverse nature of ovarian cancer and correlates the clinical, pathological, and molecular features of the disease. In this model, ovarian tumors are divided into 2 groups designated type I and type II. Type I tumors are slow growing, generally confined to the ovary at diagnosis, and develop from well-established precursor lesions that are termed "borderline" tumors. Type I tumors include low-grade micropapillary serous carcinoma, mucinous, endometrioid, and clear cell carcinomas. They are genetically stable and are characterized by mutations in a number of different genes including KRAS, BRAF, PTEN, and beta-catenin. Type II tumors are rapidly growing highly aggressive neoplasms for which well-defined precursor lesions have not been described. Type II tumors include high-grade serous carcinoma, malignant mixed mesodermal tumors (carcinosarcomas), and undifferentiated carcinomas. This group of tumors has a high level of genetic instability and is characterized by mutation of TP53. The model helps to explain why current screening techniques, aimed at detecting stage I disease, have not been effective. Tumors that remain confined to the ovary for a long period belong to the type I group, but they account for only 25% of the malignant tumors. Most of what is considered ovarian cancer belongs to the type II category, and these are only rarely confined to the ovary. Although the reasons for this are not entirely clear, possible explanations include rapid spread from the ovary early in carcinogenesis and development of carcinoma in extra ovarian sites, notably, the peritoneum and fallopian tube, with secondary involvement of the ovary. The latter tumors are advanced stage at their inception. Therefore, a more realistic end point for the early detection of ovarian cancer is volume and not stage of disease. The model does not replace the histopathologic classification but, by drawing attention to the molecular genetic events that play a role in tumor progression, sheds light on new approaches to early detection and treatment.

Early detection and treatment of ovarian cancer: shifting from early stage to minimal volume of disease based on a new model of carcinogenesis

The goal of ovarian cancer screening is to detect disease when confined to the ovary (stage I) and thereby prolong survival. We believe this is an elusive goal because most ovarian cancer, at its earliest recognizable stage, is probably not confined to the ovary. We propose a new model of ovarian carcinogenesis based on clinical, pathological, and molecular genetic studies that may enable more targeted screening and therapeutic intervention to be developed. The model divides ovarian cancer into 2 groups designated type I and type II. Type I tumors are slow growing, generally confined to the ovary at diagnosis and develop from well-established precursor lesions so-called borderline tumors. Type I tumors include low-grade micropapillary serous carcinoma, mucinous, endometrioid, and clear cell carcinomas. They are genetically stable and are characterized by mutations in a number of different genes including KRAS, BRAF, PTEN, and beta-catenin. Type II tumors are rapidly growing, highly aggressive neoplasms that lack well-defined precursor lesions; most are advanced stage at, or soon after, their inception. These include high-grade serous carcinoma, malignant mixed mesodermal tumors (carcinosarcomas), and undifferentiated carcinomas. The type II tumors are characterized by mutation of TP53 and a high level of genetic instability. Screening tests that focus on stage I disease may detect low-grade type I neoplasms but miss the more aggressive type II tumors, which account for most ovarian cancers. A more rational approach to early detection of ovarian cancer should focus on low volume rather than low stage of disease.

p63 expression in epithelial ovarian tumors

Ovarian cancer is a highly lethal disease and its underlying biology is poorly understood. The p63 is a homologue gene of the tumor suppressor p53. p63 appears to be important for the development and differentiation of reproductive epithelium and interacts with p53 in human tumorigenesis. This study presents the immunoexpression of the p63 in benign and malignant epithelial ovarian tumors. We evaluated the p63 immunoexpression in 91 ovarian benign cystadenomas (29 mucinous and 62 serous) and in 29 ovarian malignant tumors (3 mucinous borderline, 3 serous borderline, 17 serous carcinomas, 2 endometrioid, 2 undifferentiated, 1 mucinous, and 1 clear-cell carcinoma) using a monoclonal antibody clone 4A4 (1:200), which recognizes all p63 variants. The tumors were considered p63 positive if 5% or more cells presented nuclear immunostaining. We observed 85.7% of positivity in benign tumors, 50% in borderline tumors, and 8.7% in invasive ovarian cancer (P < .0001). The benign serous cystadenomas were positive in 91.9% of cases and benign mucinous cystadenomas in 72.4% (P= .02). These data suggests an important role of p63 in the control of ovarian epithelium behavior. The p63 may be involved in the development of benign and malignant epithelial ovarian tumors.

Molecular characterisation of pancreatic ductal adenocarcinoma in patients under 40

BACKGROUND

Pancreatic ductal adenocarcinoma (PDAC) rarely affects people under 40.

OBJECTIVES

To determine whether the clinical, pathomorphological and genetic features of PDAC occurring in young patients (<or=40 years) differ from those in elderly patients.

METHODS

Clinical and pathomorphological data were obtained from seven patients presenting with PDAC, with age ranging from 35 to 40 years of age (mean 38 years). All tumours were characterised by using immunohistochemistry and molecular genetics.

RESULTS

All seven patients were women and lacked an association to cancer-predisposing genetic syndromes. Four patients were smokers and one had non-hereditary chronic pancreatitis. Pathomorphologically, tumours in three patients displayed moderate differentiation and four showed poor differentiation including one adenosquamous carcinoma. All tumours showed overexpression of transforming growth factor beta1 and loss or significant reduction of Smad4. Accumulation of p53 and overexpression of epidermal growth factor receptor (EGFR) were seen in five and four patients, respectively. No expression of p16, oestrogen hormone receptor or progesterone receptor was found. Mismatch repair gene products (MutL homologue 1 (MLH1), MSH2 and MSH6) were expressed in all tumours. Mutational analyses showed K-ras mutations in only three of the seven tumours.

CONCLUSION

A large clinical, pathomorphological and genetic overlap of PDAC in young patients aged under 40 is seen with that in elderly patients. The existence of yet undefined initiating events of pancreatic carcinogenesis is suggested by the low rate of K-ras mutations, in at least a subgroup of young patients.

Molecular pathogenesis of ovarian borderline tumors: new insights and old challenges

Ovarian borderline (low malignant potential) tumors are a puzzling group of neoplasms that do not fall neatly into benign or malignant categories. Their behavior is enigmatic, their pathogenesis unclear, and their clinical management controversial, especially for serous borderline tumors (SBT), the most common type of ovarian borderline tumor. Clarifying the nature of borderline tumors and their relationship to invasive carcinoma has puzzled investigators since the category was created over 30 years ago. Much of the confusion and controversy concerning these tumors is due to a lack of understanding of their pathogenesis and an absence of a model for the development of ovarian carcinoma. This review summarizes recent molecular studies of ovarian borderline tumors with special emphasis on the role of SBT in tumor progression and its relationship to ovarian serous carcinoma.

Serous borderline tumours of the ovary

Serous borderline tumours of the ovaryIn this Expert Opinion we have invited articles from two leading groups, to discuss serous borderline tumours (serous tumours of low malignant potential) of the ovary from their own perspectives. Controversy remains over heterogeneity within this group of tumours and their relationship to ovarian cancer. Our authors discuss the histopathological classification of these tumours in relation to morphological appearances, molecular and clinical data. The significance of a micropapillary pattern is discussed, and issues related to extra-ovarian implants.

Patterns of gene expression in different histotypes of epithelial ovarian cancer correlate with those in normal fallopian tube, endometrium, and colon

PURPOSE

Epithelial ovarian cancers are thought to arise from flattened epithelial cells that cover the ovarian surface or that line inclusion cysts. During malignant transformation, different histotypes arise that resemble epithelial cells from normal fallopian tube, endometrium, and intestine. This study compares gene expression in serous, endometrioid, clear cell, and mucinous ovarian cancers with that in the normal tissues that they resemble.

EXPERIMENTAL DESIGN

Expression of 63,000 probe sets was measured in 50 ovarian cancers, in 5 pools of normal ovarian epithelial brushings, and in mucosal scrapings from 4 normal fallopian tube, 5 endometrium, and 4 colon specimens. Using rank-sum analysis, genes whose expressions best differentiated the ovarian cancer histotypes and normal ovarian epithelium were used to determine whether a correlation based on gene expression existed between ovarian cancer histotypes and the normal tissues they resemble.

RESULTS

When compared with normal ovarian epithelial brushings, alterations in serous tumors correlated with those in normal fallopian tube (P = 0.0042) but not in other normal tissues. Similarly, mucinous cancers correlated with those in normal colonic mucosa (P = 0.0003), and both endometrioid and clear cell histotypes correlated with changes in normal endometrium (P = 0.0172 and 0.0002, respectively). Mucinous cancers displayed the greatest number of alterations in gene expression when compared with normal ovarian epithelial cells.

CONCLUSION

Studies at a molecular level show distinct expression profiles of different histologies of ovarian cancer and support the long-held belief that histotypes of ovarian cancers come to resemble normal fallopian tube, endometrial, and colonic epithelium. Several potential molecular markers for mucinous ovarian cancers have been identified.

Distinction between serous tumors of low malignant potential and serous carcinomas based on global mRNA expression profiling

OBJECTIVES

The molecular pathogenesis of ovarian serous tumors of low malignant potential (S-LMP) is not well understood, although the collective data suggest that they arise through molecular mechanisms distinct from those leading to conventional serous carcinomas (S-Ca). To further examine the molecular differences between these two diseases, we studied the gene expression pattern of ovarian S-LMP and S-Ca using high-density spotted cDNA and tissue microarrays.

METHODS

Total RNA from 23 ovarian S-LMP and S-Ca was analyzed on 43,200 spot cDNA microarrays and the differential expression of proteins encoded by differentially expressed genes was validated using tissue microarrays.

RESULTS

Unsupervised hierarchical clustering analysis of filtered data showed a complete separation between S-LMP and S-Ca, based predominantly on a small set of genes expressed at higher levels in S-LMP than in S-Ca. Many genes previously identified as up-regulated in ovarian carcinoma relative to normal ovarian tissue were expressed at even higher levels in S-LMP. These genes included mucin-1, mesothelin, HE4, PAX 8, and apolipoprotein J/clusterin. Immunohistochemical staining of tissue microarrays confirmed higher expression of selected proteins encoded by these genes in the S-LMP. Few genes were expressed at a higher level in S-Ca; these included E2F1, topoisomerase IIalpha, and cyclin E, with higher levels of cyclin E protein confirmed by immunohistochemistry.

CONCLUSIONS

S-LMP and S-Ca are distinguished at the molecular level by a relatively small gene set, suggesting the pathogenesis of S-LMP as well as S-Ca may involve molecular pathways that escape detection by global gene expression profiling. In order to obtain biologically and clinically relevant information about the mechanisms involved in ovarian carcinogenesis, future studies based on molecular profiles of ovarian cancer should include analyses of low malignant potential tumors. Inclusion of such tumors is also critical to the evaluation of the efficacy of potential new diagnostic and/or therapeutic biomarkers.

Origins and molecular pathology of ovarian cancer

Epithelial ovarian cancer comprises the majority of malignant ovarian tumors in adult women. These neoplasms are classified into distinct morphologic categories based on the appearance of the epithelium into tumors of serous, mucinous, endometrioid, clear cell, transitional, squamous, mixed and undifferentiated type. Current data indicate that each of these histologic subtypes is associated with distinct morphologic and molecular genetic alterations: high-grade serous and possibly endometrioid carcinomas most probably arise from surface epithelial inclusion glands with TP53 mutations and dysfunction of BRCA1 and/or BRCA2; low-grade serous carcinomas probably arise in a stepwise fashion in an adenoma-borderline tumor-carcinoma sequence from typical to micropapillary borderline tumors to low-grade invasive serous carcinoma via activation of the RAS-RAF signaling pathway secondary to mutations in KRAS and BRAF; mucinous carcinomas arise via an adenoma-borderline tumor-carcinoma sequence with mutations in KRAS; low-grade endometrioid carcinomas arise from endometriosis via mutations in CTNNB1 (the gene encoding beta-catenin) and PTEN. Although the morphologic data strongly support an origin of clear cell carcinoma from endometriosis, there is limited data on the genetic alterations in these uncommon tumors. Thus it is likely that most low-grade, relatively indolent ovarian carcinomas of serous, mucinous and endometrioid type arise from pre-existing cystadenomas or endometriosis whereas most high-grade serous carcinomas arise without an easily identifiable precursor lesion.

Histologic Type, Organ of Origin, and Wnt Pathway Status: Effect on Gene Expression in Ovarian and Uterine Carcinomas

PURPOSE

Ovarian and uterine carcinomas manifest several differentiation patterns resembling those seen in nonneoplastic epithelia of the gynecologic tract. Specific oncogene and tumor suppressor gene defects have been associated with particular differentiation patterns in carcinomas arising in either the uterus or ovary. For instance, ovarian and uterine carcinomas with endometrioid differentiation frequently show beta-catenin mutations. Whereas type of differentiation is considered in the treatment of uterine carcinomas, it does not presently contribute to decisions about treatment of ovarian carcinomas. A widely accepted view is that the accumulation of specific gene defects and gene expression changes underlies phenotypic traits of cancers, including their response to treatment.

EXPERIMENTAL DESIGN

Using oligonucleotide microarrays to assess gene expression in 103 primary ovarian and uterine carcinomas, we sought to address whether organ of origin or type of differentiation (histotype; endometrioid versus serous) had a more substantial effect on gene expression patterns.

RESULTS

We found that effects on gene expression due to organ of origin and histotype are similar in magnitude and are parallel in that organ effects are similar in the two histotypes and histotype effects are similar in the two organs. In addition, ovarian and uterine endometrioid adenocarcinomas with beta-catenin defects show a common gene expression signature largely distinct from that seen in tumors lacking such defects.

CONCLUSIONS

Our results illustrate how organ of origin, type of differentiation, and specific molecular defects all contribute to gene expression in the most common types of ovarian and uterine cancers. The findings also imply gene expression data will be of value for stratifying ovarian cancer patients for new treatment approaches.

Patterns of p53 mutations separate ovarian serous borderline tumors and low- and high-grade carcinomas and provide support for a new model of ovarian carcinogenesis: a mutational analysis with immunohistochemical correlation

The infrequent association of serous borderline tumors (SBTs) with invasive serous carcinoma has led to the view that SBTs are unrelated to invasive serous carcinoma. Nonetheless, mortality associated with SBTs is generally attributed to malignant transformation, and traditionally these tumors have been designated as "carcinomas of low malignant potential." Previous immunohistochemical studies evaluating p53 expression and molecular genetic studies evaluating mutational status have reported that p53 overexpression and mutations are infrequent in SBTs and occur in as many as 50% to 80% of invasive serous carcinomas. The different methodologies for determining p53 status and the failure to correlate the findings with tumor grade make these studies difficult to interpret. The current study was undertaken to overcome these deficiencies and to reconcile the relationship of SBTs to invasive serous carcinoma by performing a morphologic, immunohistochemical, and molecular genetic analysis comparing SBTs with low- and high-grade serous carcinoma. The molecular genetic analysis used a highly stringent, carefully designed nucleotide-sequencing method. A total of 96 sporadic serous tumors including 25 SBTs (11 atypical proliferative serous tumors and 14 intraepithelial low-grade serous carcinomas [noninvasive micropapillary serous carcinomas, MPSCs]), 12 low-grade serous carcinomas (invasive MPSCs), and 59 high-grade serous carcinomas were analyzed for their p53 mutational status of exons 5 to 9. Functional mutations, defined as mutations resulting in the alteration of the structure of the encoded protein, were detected in 30 of 59 (50.8%) high-grade serous carcinomas and 1 (8.3%) of 12 low-grade invasive serous carcinomas compared with 2 (8%) of 25 SBTs, both of these in intraepithelial low-grade serous carcinomas (noninvasive MPSCs). The similar frequency of p53 mutations in SBTs and low-grade invasive serous carcinomas in contrast to the significantly higher frequency of p53 mutations in high-grade serous carcinomas (P < 0.0005) suggests a common lineage for SBTs and low-grade invasive serous carcinomas and supports the view that SBTs are unrelated to the usual type of invasive serous carcinoma, which is a high-grade neoplasm. Mutational status was also correlated with p53 immunoreactivity. Although p53 immunoreactivity is generally higher in those specimens containing mutant p53, immunostaining is neither sufficiently specific nor sensitive enough to predict p53 mutations. The molecular genetic findings confirm our hypothesis of dual pathways of serous carcinogenesis based on previous analyses of KRAS and BRAF mutations on the same set of cases in which KRAS and BRAF mutations were found in 60% of SBTs and low-grade serous carcinoma but not in high-grade serous carcinomas. Based on these studies, we have proposed a model of serous carcinogenesis in which SBTs are the precursors of low-grade serous carcinomas whereas the usual type of invasive serous carcinoma is a high-grade neoplasm that develops "de novo" from in situ alterations in epithelial inclusion cysts.

Molecular and prognostic distinction between serous ovarian carcinomas of varying grade and malignant potential

Profiles of gene transcription have begun to delineate the molecular basis of ovarian cancer, including distinctions between carcinomas of differing histology, tumor progression and patient outcome. However, the similarities and differences among the most commonly diagnosed noninvasive borderline (low malignant potential, LMP) lesions and invasive serous carcinomas of varying grade (G1, G2 and G3) have not yet been explored. Here, we used oligonucleotide arrays to profile the expression of 12,500 genes in a series of 57 predominantly stage III serous ovarian adenocarcinomas from 52 patients, eight with borderline tumors and 44 with adenocarcinomas of varying grade. Unsupervised and supervised analyses showed that LMP lesions were distinct from high-grade serous adenocarcinomas, as might be expected; however, well-differentiated (G1) invasive adenocarcinomas showed a strikingly similar profile to LMP tumors as compared to cancers with moderate (G2) or poor (G3) cellular differentiation, which were also highly similar. Comparative genomic hybridization of an independent cohort of five LMP and 63 invasive carcinomas of varying grade demonstrated LMP and G1 were again similar, exhibiting significantly less chromosomal aberration than G2/G3 carcinomas. A majority of LMP and G1 tumors were characterized by high levels of p21/WAF1, with concomitant expression of cell growth suppressors, gadd34 and BTG-2. In contrast, G2/G3 cancers were characterized by the expression of genes associated with the cell cycle and by STAT-1-, STAT-3/JAK-1/2-induced gene expression. The distinction between the LMP-G1 and G2-G3 groups of tumors was highly correlated to patient outcome (chi(2) for equivalence of death rates=7.681189; P=0.0056, log-rank test). Our results are consistent with the recent demonstration of a poor differentiation molecular 'meta-signature' in human cancer, and underscore a number of cell-cycle- and STAT-associated targets that may prove useful as points of therapeutic intervention for those patients with aggressive disease.

Mucinous cystic carcinoma of the pancreas: a unique cell line and xenograft model of a preinvasive lesion

Pancreatic mucinous cystic tumors (MCT) are proliferations of mucin-producing epithelia supported by an ovarian-like stroma. They are classified into adenomas (MCA), borderline (MCB) and noninvasive or invasive carcinomas (MCC). The molecular mechanisms underlying their clinical behavior are poorly understood, partly due to the lack of cellular models. We report the establishment of MCC1, the first cell line from a pancreatic MCT, deriving from the highly dysplastic cell component of a noninvasive MCC. MCC1 has mutations in codon 12 of K-RAS (GGT>GAT), codon 58 of P16 (CGA>TGA) and codon 132 of P53 (AAG>AGG). The FHIT and DPC4 genes are unaltered. Immunohistochemistry shows abnormal expression of MUC1 and p53, loss of p16 and retention of Fhit and Dpc4 in both the cell line and the highly dysplastic cells of the primary lesion. The morphological and molecular features of MCC1 and its corresponding primary tumor are consistent with a model for non-invasive MCC, where K-RAS, P16, P53 and MUC1 alterations are pre-invasive changes associated with progression of malignancy of MCT from adenoma to carcinoma. MCC1 is sensitive to 5-fluorouracil, representing the first assessment of drug sensitivity for MCC. Finally, MCC1 is a suitable model for preclinical studies, as it grows in immunodeficient mice.

Different proportions of aneusomic cells in ovarian inclusion cysts associated with serous borderline tumours and serous high-grade carcinomas support different pathogenetic pathways

Ovarian serous tumours may arise from the ovarian surface epithelium or from ovarian cortical epithelial inclusion cysts. However, little is known about the pathogenetic mechanisms involved in the progression from ovarian surface epithelium or inclusion cysts to neoplastic disease. In the present study, chromosomal aberrations typical of ovarian serous tumours were studied in ovarian surface epithelium and inclusion cysts. Ten ovaries with inclusion cysts obtained from patients without a gynaecological tumour, as well as 15 serous borderline tumours and 16 invasive high-grade serous carcinomas with inclusion cysts either in the ipsi- or in the contralateral ovary, were investigated by fluorescence in situ hybridization (FISH) using centromere enumeration probes directed against chromosomes 1, 6, 7, and X. The proportions of aneusomic cells were assessed. Trisomies 1 and 7 and monosomies 6 and X were present in the surface epithelium, inclusion cysts, and tumours, providing evidence for a link between the surface epithelium, and inclusion cysts, and serous neoplasia. Inclusion cysts generally harboured more aneusomic cells than the associated surface epithelium, suggesting an influence of the ovarian stroma on the development of chromosomal instability. Moreover, inclusion cysts associated with borderline tumours displayed a higher proportion of aneusomic cells than inclusion cysts associated with invasive high-grade carcinoma and than inclusion cysts in ovaries without neoplastic disease. These results suggest a genetic field defect of the inclusion cyst epithelium in serous borderline tumours. Invasive high-grade serous carcinomas, by contrast, may arise from single cell clones subject to a different set of genetic events.

Cyclooxygenase-2 expression in borderline ovarian tumors

OBJECTIVES

The aim of the study was to investigate by immunohistochemistry the expression of cyclooxygenase-2 (COX-2) in a single institutional series of borderline ovarian tumors (BOT). Moreover, to perform a comparative analysis, COX-2 expression was also analyzed in benign and malignant ovarian tumors.

METHODS

Paraffin-embedded sections form 51 BOT, 26 benign, and 37 malignant ovarian tumors were incubated with polyclonal antiserum against COX-2. The results were calculated as the product of the percentage of the immunostained tumor cells by the relative staining score. Cases with immunostaining values of >1 were considered COX-2-positive.

RESULTS

Thirty-four (66.7%) of fifty-one BOT were considered as COX-2-positive, and this rate was not significantly different with respect to COX-2 positivity in benign (50.0%) and in malignant (51.3%) ovarian tumors (P value = 0.23). A significantly higher percentage of COX-2 positivity was found in serous (24 of 24, 100%) with respect to mucinous (9 of 26, 34.6%) BOT (P value = 0.0001). Moreover, 7 (63.6%) of 11 endocervical-type mucinous borderline ovarian tumors were COX-2-positive with respect to only 2 of 15 (13.3%) intestinal-type mucinous BOT (P value = 0.013). The same trend was observed in benign lesions, with COX-2 positivity in 9 of 11 (81.8%) of serous versus 4 of 15 (26.7%) of mucinous tumors (P value = 0.015). On the other hand, no difference was found in the percentage of COX-2 positivity in serous (14 of 29, 48.3%) versus mucinous (5 of 8, 62.5%) ovarian carcinomas (P value = 0.22).

CONCLUSIONS

COX-2 is differently expressed in BOT according to different histotype. Moreover, an increase of COX-2 positivity was observed from mucinous intestinal BOT to frankly malignant ovarian tumors suggesting that COX-2 overexpression might be involved in mucinous ovarian carcinogenesis.

Current challenges and opportunities for research on borderline ovarian tumors

This article summarizes key issues for future research on borderline ovarian tumors that emerged at a National Cancer Institute-sponsored Borderline Ovarian Tumor Workshop held in August 2003 in Bethesda, MD. Limitations in existing research and opportunities for future advances have been highlighted. The application of new molecular techniques in combination with improved study designs holds promise for elucidating the pathogenesis of these tumors and revealing the source of the extra-ovarian lesions ("implants") with which they are frequently associated. Clarification of the etiology of borderline tumors and the pathogenesis of their associated implants is critical for improving pathological diagnosis, revising the classification system of ovarian neoplasms, and developing optimal, evidence-based clinical management algorithms.

Serous borderline (low malignant potential, atypical proliferative) ovarian tumors: Workshop perspectives

Although the category of serous borderline ovarian tumor (S-BOT) was established more than 30 years ago, the nomenclature and prognostic significance of various histological features of these neoplasms continues to engender controversy. The Borderline Ovarian Tumor Workshop was held in Bethesda, MD, in August 2003 in an attempt to examine the existing data, establish areas of agreement, and identify areas needing further investigation. This report addresses 6 areas of controversy regarding S-BOT: (1) tumors with and without a micropapillary architecture (typical vs micropapillary type), (2) peritoneal implants, (3) stromal microinvasion, (4) ovarian surface involvement, (5) lymph node involvement, and (6) recurrent tumors. Each of these issues is addressed by summarizing the data in the literature on which the discussions were based, areas of agreement that emerged, divergent opinions and the reasoning behind them, and the conclusions of the participants with recommended nomenclature.

Chemosensitivity and radiosensitivity profiles of four new human epithelial ovarian cancer cell lines exhibiting genetic alterations in BRCA2, TGFbeta-RII, KRAS2, TP53 and/or CDNK2A

To address the cellular basis for the response to ovarian cancer treatment, we characterized the chemosensitivity and radiosensitivity of four human epithelial ovarian cancer cell lines that harbor different genetic alterations. The TOV-21G, TOV-81D, OV-90, and TOV-112D cell lines were derived from ovarian tumors (TOV) or ascites (OV) from chemotherapy- and radiotherapy-naive patients and were characterized by their mutation spectrum of BRCA2, TGFbeta-RII, KRAS2, TP53, and CDKN2A. Cells were monitored for survival following exposure at various concentrations to different cytotoxic agents including cisplatin, camptothecin or paclitaxel or to different doses of gamma-irradiation. At the lowest doses, the TGFbeta-RII-mutated and KRAS2-mutated cell line, TOV-21G, and the BRCA2-mutated cell line, TOV-81D, demonstrated a significantly higher sensitivity to cisplatin and gamma-irradiation than the TP53-mutated cell lines, TOV-112D and OV-90. At higher doses, differences between the TP53-mutated lines were observed with TOV-112D being less sensitive to cisplatin than OV-90 that also harbors a CDNK2A mutation. All cell lines were similarly sensitive to high doses of gamma-irradiation. In contrast, sensitivity to camptothecin or paclitaxel was not significantly different between all cell lines, irrespective of the mutation status of BRCA1, BRCA2, TGFbeta-RII, KRAS2, TP53, and CDKN2A. The observed responses to treatment are consistent with the current knowledge concerning BRCA2, TGFbeta-RII, KRAS2, TP53, and/or CDKN2A aberrant function.

Ovarian tumorigenesis: a proposed model based on morphological and molecular genetic analysis

The pathogenesis of ovarian carcinoma, the most lethal gynecological malignancy, is unknown because of the lack of a tumor progression model. Based on a review of recent clinicopathological and molecular studies, we propose a model for their development. In this model, surface epithelial tumors are divided into two broad categories designated type I and type II tumors that correspond to two main pathways of tumorigenesis. Type I tumors tend to be low-grade neoplasms that arise in a stepwise manner from borderline tumors whereas type II tumors are high-grade neoplasms for which morphologically recognizable precursor lesions have not been identified, so-called de novo development. As serous tumors are the most common surface epithelial tumors, low-grade serous carcinoma is the prototypic type I tumor and high-grade serous carcinoma is the prototypic type II tumor. In addition to low-grade serous carcinomas, type I tumors are composed of mucinous carcinomas, endometrioid carcinomas, malignant Brenner tumors, and clear cell carcinomas. Type I tumors are associated with distinct molecular changes that are rarely found in type II tumors, such as BRAF and KRAS mutations for serous tumors, KRAS mutations for mucinous tumors, and beta-catenin and PTEN mutations and microsatellite instability for endometrioid tumors. Type II tumors include high-grade serous carcinoma, malignant mixed mesodermal tumors (carcinosarcoma), and undifferentiated carcinoma. There are very limited data on the molecular alterations associated with type II tumors except frequent p53 mutations in high-grade serous carcinomas and malignant mixed mesodermal tumors (carcinosarcomas). This model of carcinogenesis reconciles the relationship of borderline tumors to invasive carcinoma and provides a morphological and molecular framework for studies aimed at elucidating the pathogenesis of ovarian cancer.

Ovarian mucinous borderline tumors of intestinal type without intraepithelial carcinoma: Are they still tumors of low malignant potential?

The purpose of this study was to clarify whether ovarian intestinal-type mucinous borderline tumors without intraepithelial carcinoma should still be considered tumors of low malignant potential. Fifty-five intestinal-type mucinous borderline tumors without intraepithelial carcinoma in which a section had been taken for each 2 cm or less of the tumor's greatest diameter were selected. The International Federation of Gynecology and Obstetrics' stage and follow-up data of each case were examined. All 55 patients had stage I disease (including one with pseudomyxoma peritonei of superficial organizing type, according to Lee and Scully's classification). No patient had metastases or died from the tumor, although in one patient who underwent cystectomy, the disease recurred in the remaining ovary 5 years after surgery. However, the patient was alive and well after undergoing salpingo-oophorectomy. The patient with pseudomyxoma peritonei had no recurrence and did not die from the tumor. These findings indicated that intestinal-type mucinous borderline tumors, in which intraepithelial carcinoma has been ruled out with adequate histological sampling, are benign tumors, not tumors of low malignant potential. It is proposed here that these tumors should be designated as high-grade mucinous adenoma. Unilateral salpingo-oophorectomy is the recommended treatment because cystectomy alone may allow local recurrence in the remaining ovary.

Ovarian cancer and high-risk women—implications for prevention, screening, and early detection

OBJECTIVE

The aim of this study was to understand the strengths and limitations of current prevention, detection, and screening methods for ovarian cancer and to identify research areas to improve prevention, screening, and detection of the disease for all women as well as for women carrying a mutation in the BRCA1/2 genes.

METHODS

We convened an ovarian cancer symposium at the University of Pittsburgh in May 2002. Nineteen leading scientists representing disciplines such as epidemiology, molecular biology, pathology, genetics, bioinformatics, and psychology presented the latest data on ovarian cancer prevention, screening, and early detection.

RESULTS

Ovarian cancer is the most common cause of death from a gynecologic malignancy in the United States. Because survival depends on stage of diagnosis, early detection is critical in improving clinical outcome. However, existing screening techniques (CA125, transvaginal ultrasound) have not been shown to reduce morbidity or mortality. Moreover, with the exception of oral contraceptives, there are no available chemopreventive agents. Bilateral salpingo-oophorectomy also has been shown to reduce incidence, but this procedure has several drawbacks in terms of a woman's reproductive, cardiovascular, skeletal, and mental health.

CONCLUSIONS

Better methods to prevent, detect, and screen for ovarian cancer in all women, but particularly in high-risk women carrying mutations in BRCA1/2, are urgently needed. This article reviews the current state of knowledge in the etiology, prevention, and early detection of ovarian cancer and suggests several areas for future clinical, epidemiologic, and laboratory-based research.

Role of KRAS and BRAF gene mutations in mucinous ovarian carcinoma

OBJECTIVES

The goals of this study were to perform a comprehensive assessment of the prevalence of KRAS oncogene mutations in invasive epithelial ovarian carcinomas of various histologic subtypes, and for any subgroup(s) in which KRAS mutation was found to be common, to address the hypothesis that those tumors without KRAS mutation had sustained alternative activation of this signaling pathway through mutation of the BRAF oncogene.

METHODS

A total of 104 primary, invasive epithelial ovarian carcinomas from a 10-year period at this institution were selected for study based on histologic classification. The histologic cell type was serous in 21 cases, endometrioid in 30 cases, clear cell in 31 cases, and mucinous in 22 cases. Additional clinical and pathological information was abstracted from patient records, and pathology review was performed for all cases. Direct sequence analysis of exon 2 of the KRAS gene, containing codon 12, was performed using DNA isolated from all tumor specimens. Sequence analyses of exons 11 and 15 of the BRAF gene were performed for the 22 cases of mucinous ovarian carcinoma.

RESULTS

Activating KRAS mutations were more common in mucinous tumors (50%) than in all other histologic types combined (5%; P < 10(-7)). Mutation of KRAS was more common in stage I tumors than in advanced stage tumors (P = 0.0004). Of the 11 mucinous tumors with KRAS mutations, 6 were of Mullerian (endocervical) type and 5 were of gastrointestinal type. No mucinous tumor was found to harbor a BRAF mutation.

CONCLUSIONS

These data indicate that KRAS oncogene mutations exist in several histologic types of invasive epithelial ovarian carcinoma, especially stage I tumors, but are common only in tumors of mucinous histology. Mutations are equally prevalent in mucinous ovarian cancers of Müllerian and gastrointestinal types. In contrast to other solid tumor types frequently affected by KRAS mutation, mucinous ovarian cancers without a KRAS mutation have not sustained alternative activation of this signaling pathway through mutation of the BRAF oncogene.