Micropapillary serous carcinoma of the ovary has distinct patterns of chromosomal imbalances by comparative genomic hybridization compared with atypical proliferative serous tumors and serous carcinomas

Ovarian borderline tumors in the 2014 WHO classification: evolving concepts and diagnostic criteria

Borderline ovarian tumors (BOT) are uncommon but not rare epithelial ovarian neoplasms, intermediate between benign and malignant categories. Since BOT were first identified >40 years ago, they have inspired controversies disproportionate to their incidence. This review discusses diagnostic criteria for the histologic subtypes of BOT, highlighting areas of diagnostic challenges, ongoing controversies, and changes in terminology implemented by the recent 2014 WHO Classification of Tumours of the Female Genital Organs. Emerging knowledge supports the notion that subtypes of borderline ovarian tumors comprise distinct biologic, pathogenetic, and molecular entities, precluding a single unifying concept for BOT. Serous borderline tumors (SBT) share molecular and genetic alterations with low-grade serous carcinomas and can present at higher stages with peritoneal implants and/or lymph node involvement, which validates their borderline malignant potential. All other (non-serous) subtypes of BOT commonly present at stage I confined to the ovary(ies) and are associated with overall survival approaching that of the general population. An important change in the WHO 2014 classification is the new terminology of non-invasive implants associated with SBT, as any invasive foci (previously called “invasive implants”) are now in line with their biological behavior considered peritoneal low-grade serous carcinoma (LGSC). The controversy regarding the terminology of non-serous borderline tumors, called by some pathologists “atypical proliferative tumor” in view of their largely benign behavior, has not been resolved. The concepts of intraepithelial carcinoma and microinvasion may evolve in further studies, as their presence appears to have no prognostic impact and is subject to considerable inter-observer variability.

Ovarian-type epithelial tumours of the testis: immunohistochemical and molecular analysis of two serous borderline tumours of the testis

Tumours of ovarian-epithelial type of the testis, including serous borderline tumours, represent very rare entities. They are identical to the surface epithelial tumours of the ovary and have been reported in patients from 14 to 68 years of age. We describe two cases of a 46- and a 39-year old man with incidental findings of intratesticular masses of the left respectively right testis. Under the assumption of a malignant testicular tumour the patients were subjected to inguinal orchiectomy. Histologically, the tumours were identical to their ovarian counterparts: They showed a cystic configuration with a fibrous wall and irregular papillary structures lined by partially multistratified columnar cells and areas of hobnail cells. Furthermore, there was mild cytological atypia with a proliferative activity of below 5 % as proved by Ki67 staining; mitoses could not be detected. Immunohistochemically, the tumour cells displayed expression of pan-cytokeratin AE3, progesterone receptor, Wilms’ tumour protein (WT1), and PAX8 (Paired box gene 8). Estrogen receptor was expressed in one case. Octamer-binding transcription factor-4 (OCT4), calretinin, thrombomodulin, and D2-40 were not expressed. Mutation testing of BRAF revealed a BRAF V600E mutation in one case, while testing for KRAS mutations proved to be negative in both. The BRAF mutated tumour showed strong cytosolic and membranous positivity for B-Raf also on immunohistochemical analysis. Comparative genomic hybridization of one case could not reveal any chromosomal aberrations.

Intratumoral heterogeneity in a minority of ovarian low-grade serous carcinomas

Background

Ovarian low-grade serous carcinoma (LGSC) has fewer mutations than ovarian high-grade serous carcinoma (HGSC) and a less aggressive clinical course. However, an overwhelming majority of LGSC patients do not respond to conventional chemotherapy resulting in a poor long-term prognosis comparable to women diagnosed with HGSC. KRAS and BRAF mutations are common in LGSC, leading to clinical trials targeting the MAPK pathway. We assessed the stability of targetable somatic mutations over space and/or time in LGSC, with a view to inform stratified treatment strategies and clinical trial design.

Methods

Eleven LGSC cases with primary and recurrent paired samples were identified (stage IIB-IV). Tumor DNA was isolated from 1–4 formalin-fixed paraffin-embedded tumor blocks from both the primary and recurrence (n = 37 tumor and n = 7 normal samples). Mutational analysis was performed using the Ion Torrent AmpliSeq^TM Cancer Panel, with targeted validation using Fluidigm-MiSeq, Sanger sequencing and/or Raindance Raindrop digital PCR.

Results

KRAS (3/11), BRAF (2/11) and/or NRAS (1/11) mutations were identified in five unique cases. A novel, non-synonymous mutation in SMAD4 was observed in one case. No somatic mutations were detected in the remaining six cases. In two cases with a single matched primary and recurrent sample, two KRAS hotspot mutations (G12V, G12R) were both stable over time. In three cases with multiple samplings from both the primary and recurrent surgery some mutations (NRAS Q61R, BRAF V600E, SMAD4 R361G) were stable across all samples, while others (KRAS G12V, BRAF G469V) were unstable.

Conclusions

Overall, the majority of cases with detectable somatic mutations showed mutational stability over space and time while one of five cases showed both temporal and spatial mutational instability in presumed drivers of disease. Investigation of additional cases is required to confirm whether mutational heterogeneity in a minority of LGSC is a general phenomenon that should be factored into the design of clinical trials and stratified treatment for this patient population.

Electronic supplementary material

The online version of this article (doi:10.1186/1471-2407-14-982) contains supplementary material, which is available to authorized users.

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.

Ovarian serous carcinoma: recent concepts on its origin and carcinogenesis

Recent morphologic and molecular genetic studies have led to a paradigm shift in our conceptualization of the carcinogenesis and histogenesis of pelvic (non-uterine) serous carcinomas. It appears that both low-grade and high-grade pelvic serous carcinomas that have traditionally been classified as ovarian in origin, actually originate, at least in a significant subset, from the distal fallopian tube. Clonal expansions of the tubal secretory cell probably give rise to serous carcinomas, and the degree of ciliated conversion is a function of the degree to which the genetic hits deregulate normal differentiation. In this article, the authors review the evidentiary basis for aforementioned paradigm shift, as well as its potential clinical implications.

Chromosome 3 anomalies investigated by genome wide SNP analysis of benign, low malignant potential and low grade ovarian serous tumours

Ovarian carcinomas exhibit extensive heterogeneity, and their etiology remains unknown. Histological and genetic evidence has led to the proposal that low grade ovarian serous carcinomas (LGOSC) have a different etiology than high grade carcinomas (HGOSC), arising from serous tumours of low malignant potential (LMP). Common regions of chromosome (chr) 3 loss have been observed in all types of serous ovarian tumours, including benign, suggesting that these regions contain genes important in the development of all ovarian serous carcinomas. A high-density genome-wide genotyping bead array technology, which assayed >600,000 markers, was applied to a panel of serous benign and LMP tumours and a small set of LGOSC, to characterize somatic events associated with the most indolent forms of ovarian disease. The genomic patterns inferred were related to TP53, KRAS and BRAF mutations. An increasing frequency of genomic anomalies was observed with pathology of disease: 3/22 (13.6%) benign cases, 40/53 (75.5%) LMP cases and 10/11 (90.9%) LGOSC cases. Low frequencies of chr3 anomalies occurred in all tumour types. Runs of homozygosity were most commonly observed on chr3, with the 3p12-p11 candidate tumour suppressor region the most frequently homozygous region in the genome. An LMP harboured a homozygous deletion on chr6 which created a GOPC-ROS1 fusion gene, previously reported as oncogenic in other cancer types. Somatic TP53, KRAS and BRAF mutations were not observed in benign tumours. KRAS-mutation positive LMP cases displayed significantly more chromosomal aberrations than BRAF-mutation positive or KRAS and BRAF mutation negative cases. Gain of 12p, which harbours the KRAS gene, was particularly evident. A pathology review reclassified all TP53-mutation positive LGOSC cases, some of which acquired a HGOSC status. Taken together, our results support the view that LGOSC could arise from serous benign and LMP tumours, but does not exclude the possibility that HGOSC may derive from LMP tumours.

Molecular pathogenesis and extraovarian origin of epithelial ovarian cancer--shifting the paradigm

Recent morphologic, immunohistochemical, and molecular genetic studies have led to the development of a new paradigm for the pathogenesis and origin of epithelial ovarian cancer based on a dualistic model of carcinogenesis that divides epithelial ovarian cancer into 2 broad categories designated types I and II. Type I tumors comprise low-grade serous, low-grade endometrioid, clear cell and mucinous carcinomas, and Brenner tumors. They are generally indolent, present in stage I (tumor confined to the ovary), and are characterized by specific mutations, including KRAS, BRAF, ERBB2, CTNNB1, PTEN, PIK3CA, ARID1A, and PPP2R1A, which target specific cell signaling pathways. Type I tumors rarely harbor TP53 mutations and are relatively stable genetically. Type II tumors comprise high-grade serous, high-grade endometrioid, malignant mixed mesodermal tumors (carcinosarcomas), and undifferentiated carcinomas. They are aggressive, present in advanced stage, and have a very high frequency of TP53 mutations but rarely harbor the mutations detected in type I tumors. In addition, type II tumors have molecular alterations that perturb expression of BRCA either by mutation of the gene or by promoter methylation. A hallmark of these tumors is that they are genetically highly unstable. Recent studies strongly suggest that fallopian tube epithelium (benign or malignant) that implants on the ovary is the source of low-grade and high-grade serous carcinoma rather than the ovarian surface epithelium as previously believed. Similarly, it is widely accepted that endometriosis is the precursor of endometrioid and clear cell carcinomas and, as endometriosis, is thought to develop from retrograde menstruation; these tumors can also be regarded as involving the ovary secondarily. The origin of mucinous and transitional cell (Brenner) tumors is still not well established, although recent data suggest a possible origin from transitional epithelial nests located in paraovarian locations at the tuboperitoneal junction. Thus, it now appears that type I and type II ovarian tumors develop independently along different molecular pathways and that both types develop outside the ovary and involve it secondarily. If this concept is confirmed, it leads to the conclusion that the only true primary ovarian neoplasms are gonadal stromal and germ cell tumors analogous to testicular tumors. This new paradigm of ovarian carcinogenesis has important clinical implications. By shifting the early events of ovarian carcinogenesis to the fallopian tube and endometrium instead of the ovary, prevention approaches, for example, salpingectomy with ovarian conservation, may play an important role in reducing the burden of ovarian cancer while preserving hormonal function and fertility.

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.

Molecular pathogenesis of endometrial and ovarian cancer

Pregnancy, breastfeeding, and oral contraceptive pill use interrupt menstrual cycles and reduce endometrial and ovarian cancer risk. This suggests the importance of turnover within Mullerian tissues, where the accumulation of mutations in p53 and PTEN has been correlated with number of cycles. The most common type of endometrial cancer (Type I) is endometrioid and molecular abnormalities include mutations in PTEN, KRAS and β-catenin. The Type I precursor is Endometrial Intraepithelial Neoplasia which displays PTEN defects. Type II endometrial cancer (whose precursors are less clear) includes serous and clear cell tumors and the most common alteration is p53 mutation. For ovarian cancer, histopathologic types parallel endometrial cancer and include serous, mucinous, endometrioid, and clear cell; some molecular features are also shared. The most frequent type of ovarian cancer is high grade serous that often displays p53 mutation and its precursor lesions may originate from normal-appearing fallopian tube epithelium that contains a p53 "signature". Mutations in KRAS, BRAF and PTEN are described in mucinous, endometrioid and low grade serous cancers and these may originate from ovarian cortical inclusion cysts. A consideration of molecular and other pathogenetic features, like epidemiology and histopathology, may provide a better understanding of endometrial and ovarian cancer.

Ovarian low-grade and high-grade serous carcinoma: pathogenesis, clinicopathologic and molecular biologic features, and diagnostic problems

Ovarian serous carcinomas have been graded using various systems. Recently, a 2-tier system in which tumors are subdivided into low grade and high grade has been proposed. This approach is simplistic, reproducible, and based on biologic evidence indicating that both tumors develop via different pathways. Low-grade serous carcinomas exhibit low-grade nuclei with infrequent mitotic figures. They evolve from adenofibromas or borderline tumors, have frequent mutations of the KRAS, BRAF, or ERBB2 genes, and lack TP53 mutations (Type I pathway). The progression to invasive carcinoma is a slow step-wise process. Low-grade tumors are indolent and have better outcome than high-grade tumors. In contrast, high-grade serous carcinomas have high-grade nuclei and numerous mitotic figures. Identification of a precursor lesion in the ovary has been elusive and therefore the origin of ovarian carcinoma has been described as de novo. More recently, studies have suggested that a proportion seem to originate from intraepithelial carcinoma in the fallopian tube. The development of these tumors is rapid (Type II pathway). Most are characterized by TP53 mutations and lack mutations of KRAS, BRAF, or ERBB2. Although both types of serous carcinomas evolve along different pathways, rare high-grade serous carcinomas seem to arise through the Type I pathway. Immunohistochemical stains for p53, p16, and Ki-67 for distinction of low-grade from high-grade tumors are of limited value but can be helpful in selected instances. This review provides an update on the pathogenesis and clinicopathologic features of these 2 types of serous carcinomas and addresses some of the diagnostic problems that are encountered in routine practice.

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.

Transcriptome analysis of serous ovarian cancers identifies differentially expressed chromosome 3 genes

Cytogenetic, molecular genetic and functional analyses have implicated chromosome 3 genes in epithelial ovarian cancers (EOC). To further characterize their contribution to EOC, the Affymetrix U133A GeneChip(R) was used to perform transcriptome analyses of chromosome 3 genes in primary cultures of normal ovarian surface epithelial (NOSE) cells (n = 14), malignant serous epithelial ovarian tumors (TOV) (n = 17), and four EOC cell lines (TOV-81D, TOV-112D, TOV-21G, and OV-90). A two-way comparative analysis of 735 known genes and expressed sequences identified 278 differentially expressed genes, where 43 genes were differentially expressed in at least 50% of the TOV samples. Three genes, RIS1 (at 3p21.31), GBE1 (at 3p12.2), and HEG1 (at 3q21.2), were similarly underexpressed in all TOV samples. Deregulation of the expression of these genes was not associated with loss of heterozygosity (LOH) of the genetic loci harboring them. LOH analysis of the RIS1, GBE1, and HEG1 loci was observed at frequencies of 14.3%, 13.7%, and 9.2%, respectively, in a series of 66 malignant TOV samples of the serous subtype. Reduced expression levels of RIS1, GBE1, and HEG1 were observed only in the tumorigenic EOC cell lines (TOV-21G, TOV-112D, and OV-90) and did not correlate with LOH. These results combined suggest that RIS1, GBE1, and HEG1, unlike classical tumor suppressor genes, are not likely to be primary targets of inactivation. This study provides a comprehensive analysis of chromosome 3 gene expression in NOSE and in EOC samples and identifies chromosome 3 gene candidates for further study.

Amplicon profiles in ovarian serous carcinomas

Ovarian serous carcinoma is the most common and lethal type of ovarian cancer and its molecular etiology remains poorly understood. As an ongoing effort to elucidate the pathogenesis of ovarian serous carcinomas, we assessed the DNA copy number changes in 33 high-grade serous carcinomas and 10 low-grade serous tumors by using a genome-wide technique, single nucleotide polymorphism array, performed on affinity-purified tumor cells from fresh surgical specimens. Compared to low-grade tumors, high-grade serous carcinomas showed widespread DNA copy number changes. The most frequent alterations were in loci harboring candidate oncogenes: cyclin E1 (CCNE1), AKT2, Notch3 and PIK3CA as well as in novel loci, including 12p13, 8q24, 12p13 and 12q15. Seven amplicons were selected for dual color fluorescence in situ hybridization analysis in approximately 90 high-grade serous carcinomas and 26 low-grade serous tumors, and a high level of DNA copy number gain (amplification) was found in CCNE1, Notch3, HBXAP/Rsf-1, AKT2, PIK3CA and chr12p13 occurring in 36.1%, 7.8%, 15.7%, 13.6%, 10.8% and 7.3% of high-grade serous carcinomas. In contrast, we did not observe high level of ERBB2 amplification in any of the samples. Low-grade tumors did not show DNA copy number gain in any of the loci, except in 2 (8%) of 24 low-grade tumors showing low copy number gain in the Notch3 locus. Taken together, our results provide the first comprehensive analysis of DNA copy number changes in highly pure ovarian serous carcinoma. These findings may have important biological and clinical implications.

Molekularpathologie der epithelialen Ovarialneoplasien

Despite the fact that ovarian carcinomas are phenotypically heterogeneous, they can be divided into two main groups with common pathogenetic mechanisms. Based on clinical, pathological and molecular parameters, a relatively large group of tumors can be distinguished with stepwise development from benign precursors and borderline tumors to invasive carcinomas (type I). Depending on the morphological phenotype, characteristic genetic changes can be observed, such as mutations in KRAS and BRAF in serous borderline tumors and low-grade serous carcinomas. Mutations in KRAS are also frequently detected in mucinous borderline tumors and mucinous carcinomas. The group of endometrioid tumors is characterized by mutations in components of the Wnt-signal transduction pathway and PTEN or microsatellite instability. The second large group of tumors (type II) includes tumors with "de novo" development of highly malignant carcinomas such as the conventional (moderately to poorly differentiated) high-grade serous carcinomas, undifferentiated carcinomas and malignant mixed mesodermal tumors. These tumors are associated with frequent mutations in p53 and complex chromosomal alterations. In the future, the combined analysis of morphological parameters, genetic changes, gene-expression profiling and protein data will reveal possible diagnostic and therapeutic targets for ovarian carcinomas.

Comparative genome hybridization reveals specific genomic imbalances during the genesis from benign through borderline to malignant ovarian tumors

Ovarian cancer is one of the most common types of malignancy in women throughout the developed world. Despite recent therapeutic advances, long-term survival is poor because ovarian cancer is largely asymptomatic in its early stages. Comparative genomic hybridization (CGH) was applied to a series of 8 benign, 8 borderline, and 17 malignant ovarian to establish genomic imbalances associated with tumor progression. Benign and borderline tumors were characterized by losses at 1p32 approximately p11, 2q14 approximately q34, 4q13 approximately q34, 5q11 approximately q23, and 6q12 approximately q24, as well as gains of 6p and chromosome 12. Similar chromosomal changes were also detected in malignant tumors but included additional chromosomal changes: gains at 1q21 approximately q31, 2p, 3q, 5p, 7, 10p, 12p, 16p, 17, 19q, 20q, and 22q, as well as losses at X, 3p, 8p, 9, 11p, 13, 14, and 18. Some individual cases of benign and borderline tumors revealed no genetic alterations detectable by CGH, suggesting that these tumors may represent a subset of tumors that originate by an alternative mechanism of tumorigenesis. Furthermore, our findings reveal that borderline tumors are more similar to benign tumors than to malignant tumors with respect to their genetic profiles.

Chromosomal losses of regions on 5q and lack of high-level amplifications at 8q24 are associated with favorable prognosis for ovarian serous carcinoma

In this study, we describe characteristic chromosomal alterations in a consecutive series of 96 serous ovarian tumors by comparative genomic hybridization. We analyze their association with different pathways of progression, histological grade, and clinical outcome. The most striking difference between low-grade and high-grade serous carcinomas was seen in a higher incidence of chromosomal gains at 3q and 20q and losses of 13q in the high-grade carcinomas. In addition, high-level amplifications were significantly more frequent in high-grade carcinomas, specifically involving regions on 3q and 8q. Chromosomal amplifications of 19p and 19q and losses of 4q and 5q were among the most frequent changes found in both low-grade and high-grade carcinomas, distinguishing them from borderline tumors, which had very few recurrent alterations. The most significant impact on survival of patients with invasive carcinomas Stage II-IV was observed for high-level amplifications of regions on 8q (mean overall survival (OS) 69 versus 27 months, P = 0.0006). Interestingly, low-level gains on 8q do not show any impact compared to cases with no alteration. Surprisingly, chromosomal losses on 5q had a protective impact (mean OS 36 versus 76 months, P = 0.0007). Combination of both parameters resulted in two risk groups. Low risk: loss on 5q, no amplification on 8q (mean OS 84 months); high risk: no loss on 5q, amplification on 8q (mean OS 26 months). This difference is even more pronounced, if only cases with residual tumor of less than 2 cm are included, resulting in a 5-year survival of 100% and 0% (P = 0.0005).

Genetic alterations of serous borderline tumors of the ovary compared to stage I serous ovarian carcinomas

Borderline tumors of the ovary comprise 10-20% of all epithelial ovarian tumors, and are placed between clearly benign and obviously malignant ovarian tumors. The issue of whether borderline tumors are precursors of invasive carcinoma or distinct clinical entities, however, is still the subject of discussion. To increase our understanding in relation to this issue, the aim of our study was to analyze both serous borderline and invasive ovarian tumors, and to investigate early carcinogenesis in serous ovarian tumors. Using comparative genomic hybridization, we compared cytogenetic changes in borderline ovarian tumors and stage I invasive tumors. The average number of genetic alterations differed significantly between the borderline and the invasive tumors (1.9 and 9.2, respectively). The most common genetic alterations among the borderline tumors were loss of chromosome 17, 20q, and 18p, and gain of 12p13 approximately q23. These changes were also found among the invasive tumors in a similar percentage. In conclusion, we found four distinct cytogenetic alterations that might be early events in serous ovarian tumors, and that might also characterize a subgroup of borderline ovarian tumors that may have the potential to progress and develop malignancy.

Tumor protein D52 (TPD52) is overexpressed and a gene amplification target in ovarian cancer

Recurrent chromosome 8q gain in ovarian carcinoma is likely to reflect the existence of multiple target loci, as the separate gain of chromosome bands 8q21 and 8q24 has been reported in independent studies. Since tumor protein D52 (TPD52) has been identified as a chromosome 8q21 amplification target in breast and prostate carcinoma, we compared TPD52 expression in normal ovarian epithelium (n = 9), benign serous adenomas (n = 11), serous borderline tumors (n = 6) and invasive carcinomas of the major histologic subtypes (n = 57) using immunohistochemistry. These analyses revealed that all normal ovarian epithelium samples and benign serous tumors were predominantly TPD52-negative, whereas TPD52 was overexpressed in most (44/57; 77%) ovarian carcinomas regardless of histologic subtype. TPD52 subcellular localization was predominantly cytoplasmic, although nuclear localization was also frequently observed in mucinous and clear cell carcinomas. In an independent cohort of stage III serous carcinomas (n = 18), we also directly compared in situ TPD52 expression using immunohistochemistry and TPD52 copy number using interphase FISH analyses. This revealed that TPD52 dosage and TPD52 expression were significantly positively correlated. TPD52 therefore represents a novel molecular marker in ovarian cancer, which is broadly expressed across the different histologic subtypes and whose upregulation frequently reflects increased TPD52 copy number.

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.

Nuclear size distinguishes low- from high-grade ovarian serous carcinoma and predicts outcome

A dualistic model for ovarian serous carcinogenesis based on morphological and molecular genetic studies has recently been proposed. This model divides serous carcinoma into low- and high-grade tumors, which develop along distinct molecular pathways. In this report, we evaluated computerized morphometry to determine its utility in distinguishing low- and high-grade serous carcinoma. The mean nuclear area (MNA) and the volume percentage of epithelium (VPE) in 93 high-grade serous carcinomas was measured and compared with 16 low-grade serous carcinomas and 21 serous borderline tumors, the putative precursor of low-grade serous carcinoma. We found that both MNA and VPE were significantly higher in high-grade serous carcinoma compared with low-grade serous carcinoma and serous borderline tumors (P < .001 and P = .02, respectively). There was no significant difference in MNA and VPE between low-grade carcinoma and serous borderline tumors (P > .3). Among high-grade serous carcinomas, those with an MNA of 46 microm2 or higher had a poorer survival (P = .035) than those with an MNA below 46 microm2. In contrast, VPE and tumor grade (moderately versus poorly differentiated) had no significant prognostic value. The morphometry findings lend further support to the dualistic model of ovarian serous carcinogenesis and suggest that MNA is an excellent adjunctive tool for distinguishing low- from high-grade serous carcinomas. In addition, MNA is an independent prognostic factor for high-grade serous carcinoma.

Serous and mucinous borderline (low malignant potential) tumors of the ovary

The prognosis for stage I serous borderline ovarian tumors (SBOTs) is thought to be excellent, despite rare, late recurrences. The behavior of advanced-stage SBOTs primarily depends on the invasiveness vs noninvasiveness of associated extraovarian implants. Pelvic and abdominal lymph node involvement and foci of microinvasion do not seem to adversely affect prognosis. Serous tumors with a micropapillary and/or cribriform growth pattern seem to be more frequently bilateral and exophytic and manifest at an advanced stage with a higher incidence of invasive implants than typical SBOTs. Molecular data suggest that such tumors may represent an intermediate stage in the typical SBOT-invasive low-grade serous carcinoma progression. Limited experience with endocervical (müllerian)-type mucinous borderline tumors shows a possible relation to SBOTs in clinicopathologic features and biologic behavior Intestinal-type mucinous borderline ovarian tumors (I-MBOTs) and well-differentiated mucinous carcinomas manifest at stage I in most cases; the prognosis is excellent. Mucinous tumors associated with pseudomyxoma peritonei are almost always secondary to similar tumors of the appendix or other gastrointestinal sites and should not be diagnosed as high-stage I-MBOTs. Rare primary ovarian mucinous tumors associated with pseudomyxoma peritonei are those arising in mature cystic teratomas. Advanced-stage ovarian mucinous carcinomas typically show frank, infiltrative-type invasion; the prognosis is poor.

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.

High-resolution mapping of genomic imbalance and identification of gene expression profiles associated with differential chemotherapy response in serous epithelial ovarian cancer

Array comparative genomic hybridization (aCGH) and microarray expression profiling were used to subclassify DNA and RNA alterations associated with differential response to chemotherapy in ovarian cancer. Two to 4 Mb interval arrays were used to map genomic imbalances in 26 sporadic serous ovarian tumors. Cytobands 1p36, 1q42-44, 6p22.1-p21.2, 7q32.1-q34 9q33.3-q34.3, 11p15.2, 13q12.2-q13.1, 13q21.31, 17q11.2, 17q24.2-q25.3, 18q12.2, and 21q21.2-q21.3 were found to be statistically associated with chemotherapy response, and novel regions of loss at 15q11.2-q15.1 and 17q21.32-q21.33 were identified. Gene expression profiles were obtained from a subset of these tumors and identified a group of genes whose differential expression was significantly associated with drug resistance. Within this group, five genes (GAPD, HMGB2, HSC70, GRP58, and HMGB1), previously shown to form a nuclear complex associated with resistance to DNA conformation-altering chemotherapeutic drugs in in vitro systems, may represent a novel class of genes associated with in vivo drug response in ovarian cancer patients. Although RNA expression change indicated only weak DNA copy number dependence, these data illustrate the value of molecular profiling at both the RNA and DNA levels to identify small genomic regions and gene subsets that could be associated with differential chemotherapy response in ovarian cancer.

Borderline epithelial tumors of the ovary

The concept and terminology of borderline epithelial tumors of the ovary have been controversial for over a century, in spite of the acceptance of a borderline category in almost all current classifications of ovarian tumors. Typically, borderline tumors are noninvasive neoplasms that have nuclear abnormalities and mitotic activity intermediate between benign and malignant tumors of similar cell type. Borderline tumors of all surface epithelial cell types have been studied. The most common and best understood are serous borderline tumors and mucinous borderline tumors of intestinal type, which are the subject of this review. Some of the most challenging issues for serous tumors include: the criteria and clinical behavior of stromal microinvasion; the high prevalence of synchronous extraovarian disease; the classification and histopathologic features of associated peritoneal tumor implants, especially invasive implants; and, the prognostic significance of micropapillary tumors. The mucinous borderline tumors of intestinal type have a different set of considerations, including: their frequently heterogeneous composition with coexisting benign, borderline and malignant elements; the classification and significance of accompanying noninvasive carcinoma; the recognition of stromal invasion, including microinvasion and expansile invasion; and, the historically misunderstood relationship to pseudomyxoma peritonei. All of these issues are discussed in this presentation, as are the important gross and microscopic features of serous and mucinous borderline tumors and pertinent information on their treatment and prognosis.

Advanced molecular cytogenetics in human and mouse

Fluorescence in situ hybridization, spectral karyotyping, multiplex fluorescence in situ hybridization, comparative genomic hybridization, and more recently array comparative genomic hybridization, represent advancements in the field of molecular cytogenetics. The application of these techniques for the analysis of specimens from humans, or mouse models of human diseases, enables one to reliably identify and characterize complex chromosomal rearrangements resulting in alterations of the genome. As each of these techniques has advantages and limitations, a comprehensive analysis of cytogenetic aberrations can be accomplished through the utilization of a combination approach. As such, analyses of specific tumor types have proven invaluable in the identification of new tumor-specific chromosomal aberrations and imbalances (aneuploidy), as well as regions containing tumor-specific gene targets. Application of these techniques has already improved the classification of tumors into distinct categories, with the hope that this will lead to more tailored treatment strategies. These techniques, in particular the application of tumor-specific fluorescence in situ hybridization probes to interphase nuclei, are also powerful tools for the early identification of premalignant lesions.

Gene expression microarray analysis and genome databases facilitate the characterization of a chromosome 22 derived homogeneously staining region

Karyotype and fluorescence in situ hybridization (FISH) analyses previously identified a homogeneously staining region (HSR) derived from chromosome 22 in OV90, an epithelial ovarian cancer (EOC) cell line. Affymetrix expression microarrays in combination with the UniGene and Human Genome Browser databases were used to identify the candidate genes comprising the amplicon of the HSR, based on comparison of expression profiles of OV90, EOC cell lines lacking HSRs and primary cultures of normal ovarian surface epithelial (NOSE) cells. A group of probe sets displaying a minimum 3-fold overexpression with a high reliability score (P-call) in OV90 were identified which represented genes that mapped within a 1-2 Mb interval on chromosome 22. A large number of probe sets, some of which represent the same genes, displayed no evidence of overexpression and/or low reliability scores (A-call). An investigation of the probe set sequences with the Affymetrix and Sanger Institute Chromosome 22 Group databases revealed that some of the probe sets displaying discordant results for the same gene were complementary to intronic sequences and/or the antisense strand. Microarray results were validated by RT-PCR. Genomic analysis suggests that the HSR was derived from the amplification of a 1.1 Mb interval defined by the chromosomal map positions of ZNF74 and Hs.372662, at 22q11.21. The deduced amplicon is derived from a complex region of chromosome 22 that harbors low-copy repeats (LCRs). The amplicon contains 18 genes as likely targets for gene amplification. This study illustrates that large-scale expression microarray analysis in combination with genome databases is sufficient for deducing target genes associated with amplicons and stresses the importance of investigating probe set design before engaging in validation studies.

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.

The use of cytogenetics in understanding ovarian cancer

The future of cancer research is no longer limited to epidemiological data and clinical management, but rather encompasses a new dimension of understanding, that involves genetics of the tumors themselves. This has been exemplified most prominently in hematological tumors where alterations at the DNA level have been found to play key roles in the pathophysiology, diagnosis, monitoring and prognosis of these tumors. It has been shown over the last 20 years that recurrent chromosomal rearrangements are strongly associated with the activation of oncogenes, acquisition of drug resistance and loss of tumor suppressor gene function. Chromosomal alterations have also been shown to characterize many solid tumors, including epithelial ovarian cancer [Cancer Res. 62 (2002) 3466; Cancer 91 (2001) 534; Genes Chromosomes Cancer 25 (1999) 290]. Despite these findings, however, there are currently few examples of specific cytogenetic studies that have contributed to the clinical management of solid tumors such as ovarian cancer. The limiting factor to date is the resolution of available techniques. With time, as the technology improves, so will our ability to focus on specific findings that may be applicable to future clinical management. The intention of this report is to familiarize the reader with the evolution of cytogenetic and molecular cytogenetic techniques used in the study of ovarian cancer, the early formulations from these studies and their use in answering specific clinical questions such as association with pathologic subtype, the relevance of drug resistance, the impact of BRCA mutations, and finally to guide the reader into the future of this ever growing field.

Borderline ovarian tumors: key points and workshop summary

This article documents major points of agreement and disagreement among experts invited to participate in a Borderline Ovarian Tumor Workshop held in Bethesda, MD, on August 27-28, 2003. It is suggested that controversies related to the diagnosis and management of these tumors are often related to lack of data in the literature (small numbers of cases, unreported or unclear criteria for diagnosis and follow-up, insufficient length of follow-up, etc), and specific recommendations are made for further investigation and for reporting of data in future studies.

Analysis of Molecular Aberrations in Ovarian Cancer Allows Novel Target Identification

The completion of the Human Genome Project and recent advances in functional genomic, proteomic, and high-throughput screening methodologies have provided powerful tools for determining the mechanisms of human diseases, including complex polygenic diseases such as ovarian cancer. These developments may eventually lead to individualized molecular medicine, which is the treatment of patients based on the underlying genetic defects in their tumours and their own genetic makeup. A plethora of novel therapeutic agents that act on specific molecular targets defined by cancer genetics are under development. There is thus a great deal of interest in determining how specific genes and proteins function in cancers, in order to further the understanding of cancer initiation and progression; to aid in identifying biomarkers, therapeutic targets, and determinants of drug responsiveness; and to progress the development of novel antitumour agents.

WT-1 assists in distinguishing ovarian from uterine serous carcinoma and in distinguishing between serous and endometrioid ovarian carcinoma

AIMS

It has been suggested that WT-1 is helpful in distinguishing a primary ovarian serous carcinoma (OSC) from a primary uterine serous carcinoma (USC). Since both neoplasms are often disseminated at diagnosis and since USC often spreads to the ovary and vice versa, it may be difficult to ascertain the primary site. This is important, since adjuvant therapies for OSC and USC may differ. WT-1 staining patterns also differ between OSC and ovarian endometrioid carcinoma and so it is possible that WT-1 may assist in the distinction of these two neoplasms, which is sometimes problematic, especially with poorly differentiated tumours. This study aims to document the value of WT-1 in these settings. Cases of ovarian borderline serous tumour, primary peritoneal serous carcinoma (PPSC) and uterine endometrioid carcinoma were also studied.

METHODS AND RESULTS

Cases of OSC (n = 38), USC (n = 25) (in five of these cases there was also a component of endometrioid adenocarcinoma), ovarian endometrioid carcinoma (n = 13), uterine endometrioid carcinoma (n = 7), ovarian borderline serous tumour (n = 16) and PPSC (n = 6) were stained with WT-1. Cases were scored on a scale of 0-3, depending on the percentage of positive cells. The intensity of staining was scored as weak, moderate or strong. There was positive nuclear staining of 36 of 38 (94.7%) OSC with WT-1. In most OSC (68.4%), >50% of cells stained positively and staining was usually strong. Five of 25 (20%) USC were positive with only two cases exhibiting staining of >50% of cells. All primary ovarian and uterine endometrioid carcinomas were negative. All PPSC were positive, usually with diffuse strong immunoreactivity. Fourteen of 16 borderline serous tumours exhibited positivity with WT-1.

CONCLUSIONS

WT-1 is useful in distinguishing OSC (characteristically diffuse strong nuclear positivity) from USC (characteristically negative). However, rarely OSC is negative and occasional cases of USC are positive. WT-1 may also be helpful in differentiating poorly differentiated OSC from poorly differentiated ovarian endometrioid carcinoma.