The fallopian tube: primary site of most pelvic high-grade serous carcinomas

Ovarian Cancer Is an Imported Disease: Fact or Fiction?

The cell of origin of ovarian cancer has been long debated. The current paradigm is that epithelial ovarian cancer (EOC) arises from the ovarian surface epithelium (OSE). OSE is composed of flat, nondescript cells more closely resembling the mesothelium lining the peritoneal cavity, with which it is continuous, rather than the various histologic types of ovarian carcinoma (serous, endometrioid, and clear cell carcinoma), which have a Müllerian phenotype. Accordingly, it has been argued that the OSE undergoes a process termed "metaplasia" to account for this profound morphologic transformation. Recent molecular and clinicopathologic studies not only have failed to support this hypothesis but also have provided evidence that EOC stems from Müllerian-derived extraovarian cells that involve the ovary secondarily, thereby calling into question the very existence of primary EOC. This new model of ovarian carcinogenesis proposes that fallopian tube epithelium (benign or malignant) implants on the ovary to give rise to both high-grade and low-grade serous carcinomas, and that endometrial tissue implants on the ovary and produces endometriosis, which can undergo malignant transformation into endometrioid and clear cell carcinoma. Thus, ultimately EOC is not ovarian in origin but rather is secondary, and it is logical to conclude that the only true primary ovarian neoplasms are germ cell and gonadal stromal tumors analogous to tumors in the testis. If this new model is confirmed, it has profound implications for the early detection and treatment of "ovarian cancer."

DNA Damage Response is Prominent in Ovarian High-Grade Serous Carcinomas, Especially Those with Rsf-1 (HBXAP) Overexpression

DNA damage commonly occurs in cancer cells as a result of endogenous and tumor microenvironmental stress. In this study, we applied immunohistochemistry to study the expression of phosphorylated Chk2 (pChk2), a surrogate marker of the DNA damage response, in high grade and low grade of ovarian serous carcinoma. A phospho-specific antibody specific for threonine 68 of Chk2 was used for immunohistochemistry on a total of 292 ovarian carcinoma tissues including 250 high-grade and 42 low-grade serous carcinomas. Immunostaining intensity was correlated with clinicopathological features. We found that there was a significant correlation between pChk2 immunostaining intensity and percentage of pChk2 positive cells in tumors and demonstrated that high-grade serous carcinomas expressed an elevated level of pChk2 as compared to low-grade serous carcinomas. Normal ovarian, fallopian tube, ovarian cyst, and serous borderline tumors did not show detectable pChk2 immunoreactivity. There was no significant difference in pChk2 immunoreactivity between primary and recurrent high-grade serous carcinomas. In high-grade serous carcinomas, a significant correlation (P < 0.0001) in expression level (both in intensity and percentage) was found between pChk2 and Rsf-1 (HBXAP), a gene involved in chromatin remodeling that is amplified in high-grade serous carcinoma. Our results suggest that the DNA damage response is common in high-grade ovarian serous carcinomas, especially those with Rsf-1 overexpression, suggesting that Rsf-1 may be associated with DNA damage response in high-grade serous carcinomas.

Biomarker expression in pelvic high-grade serous carcinoma: comparison of ovarian and omental sites

Neoadjuvant therapy has an emerging role in the treatment of high-stage ovarian carcinoma. Some ovarian carcinoma subtypes do not respond well to standard chemotherapy, making accurate subtype diagnosis before starting therapy important. This diagnosis is frequently based on omental biopsy specimens. In particular, with very small biopsies, immunostaining for diagnostic biomarkers may be needed. To assess intratumoral heterogeneity of biomarker expression in pelvic high-grade serous carcinoma, we compared the expression of a set of 10 biomarkers between ovarian and omental sites. Tissue microarrays were constructed from 123 high-grade serous carcinomas with paired ovarian and omental tumor samples. These samples were stained with biomarkers that have been used in ovarian carcinoma subtype diagnosis (WT1, TP53/p53, MUC16/CA125, CDKN2A/p16), and with biomarkers of the tumor microenvironment (CD8, CD163, SPARC, PDGFRB), cell adhesion (CDH1/E-Cadherin), and proliferation (Ki67) as well. Expression frequencies in samples from the 2 sites were compared, as was concordance at the 2 sites for individual tumors. The 2 markers of desmoplastic stromal response (PDGFRB, SPARC) were more frequently expressed in the omentum compared with the ovary (P<0.001; McNemar test). The other 8 markers did not show a significant difference in the frequency of expression between sites. Within individual cases, some markers such as Ki67 and CDKN2A showed variability, indicating that these markers are affected by intratumoral heterogeneity. The intratumoral variability for MUC16, TP53, and WT1 was modest. Commonly used diagnostic markers, such as TP53 and WT1, show little variability between ovarian and omental sites, suggesting that they can be successfully used in small biopsy specimens from extraovarian sites. In contrast, markers of host stromal response do vary between sites, suggesting a biologic difference of the microenvironment at different sites that should be taken into account when tissue-based research is carried out.

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.

Occupation and risk of primary fallopian tube carcinoma in Nordic countries

The aetiology of primary Fallopian tube carcinoma (PFTC) is poorly understood. Occupational exposures may contribute to PFTC risk. We studied incidence of PFTC in occupational categories in the Nordic female population aged 30-64 years during the 1960, 1970, 1980/1981 and/or 1990 censuses in Denmark, Finland, Iceland, Norway and Sweden. Standardized incidence ratios (SIRs) for the years following inclusion in the study up to 2005 were calculated for 53 occupations; the expected numbers of cases were based on PFTC incidence in the national populations. Altogether 2,206 PFTC cases were detected during follow up via data linkages with the Nordic cancer registries. Significantly increased risks of PFTC were observed for smelting workers (SIR 3.99, 95% confidence interval 1.46-8.68, Obs = 6), artistic workers (2.64, 1.44-4.43, Obs = 14), hairdressers (2.18, 1.41-3.22, Obs = 25), packers (1.62, 1.11-2.29, Obs = 32), nurses (1.49, 1.14-1.92, Obs = 60), shop workers (1.25, 1.07-1.46, Obs = 159) and clerical workers (1.20, 1.07-1.35, Obs = 271) and these sustained over times and different Nordic countries. There was a nonsignificant increased risk for PFTC among welders, printers, painters and chemical process workers. The risk was significantly and consistently low for women working in farming (0.68, 0.47-0.95, Obs = 34) and among economically inactive women (0.88, 0.82-0.94, Obs = 833). The possible role of occupational exposures to the PFTC risks found in this study must be further evaluated in studies with a possibility to adjust for possible confounding factors, such as reproductive and life-style factors, which was not possible in our study.

Autoantibodies to mesothelin in infertility

BACKGROUND

According to extensive epidemiologic data, infertility is associated with increased ovarian cancer risk. Previous studies showed that both women with infertility and those with ovarian cancer have autoantibodies to ovarian antigens. The objective was to determine if women with infertility have antibodies to mesothelin, a well-characterized ovarian cancer antigen.

METHODS

Sera were obtained from women with infertility (n = 109), ovarian cancer (n = 28), benign ovarian tumors or cysts (n = 24), and from healthy women (n = 152). Infertility included those with a risk for ovarian cancer; endometriosis (n = 23), ovulatory dysfunction (n = 17), premature ovarian failure (POF; n = 25) and unexplained infertility (n = 44). Sera were assayed for mesothelin antibodies and for circulating mesothelin antigen by immunoassay and compared with assay control sera (n = 16) to determine a positive result.

RESULTS

Mesothelin antibodies were significantly more frequent in women with prematurely reduced ovarian function including ovulatory dysfunction (59%), ovarian failure (44%) and unexplained infertility (25%) compared with controls. In contrast, women with endometriosis, who also have a high risk for ovarian cancer, did not have mesothelin antibodies. Serum levels of mesothelin were rarely elevated in women with infertility but were high in most patients with ovarian cancer.

CONCLUSIONS AND IMPACT

We show for the first time that antibodies to mesothelin, a well-characterized ovarian cancer antigen, occur in some women with epidemiologic risk for ovarian cancer. The results suggest it may be possible to identify which women with infertility have ovarian cancer risk.

Clinical Considerations of BRCA1- and BRCA2-Mutation Carriers: A Review

Individuals who carry an inherited mutation in the breast cancer 1 (BRCA1) and BRCA2 genes have a significant risk of developing breast and ovarian cancer over the course of their lifetime. As a result, there are important considerations for the clinician in the counseling, followup and management of mutation carriers. This review outlines salient aspects in the approach to patients at high risk of developing breast and ovarian cancer, including criteria for genetic testing, screening guidelines, surgical prophylaxis, and chemoprevention.

The 'incessant menstruation' hypothesis: a mechanistic ovarian cancer model with implications for prevention

Serous, endometrioid, clear cell and mucinous histotypes are the most common epithelial ovarian cancer. Most serous cancers appear to originate from precursor lesions at the fimbriated tubal end, whereas most endometrioid and clear cell cancers seem to derive from atypical endometriosis. Data regarding hormonal factors and associated gynaecologic conditions were critically analysed with the objective of defining a carcinogenic model for sporadic epithelial ovarian cancer complying with epidemiologic and pathologic findings. Oral contraceptives and tubal ligation substantially reduce the risk of serous, endometrioid and clear cell subgroups, but have no significant effect on mucinous tumours, which probably follow a different oncogenic pathway. We hypothesize that serous, endometrioid and clear cell cancers share a common pathogenic mechanism, i.e. iron-induced oxidative stress derived from retrograde menstruation. Fimbriae floating in bloody peritoneal fluid are exposed to the action of catalytic iron and to the genotoxic effect of reactive oxygen species, generated from haemolysis of erythrocytes by pelvic macrophages. This would explain the distal site of tubal intraepithelial neoplasia. Collection of blood inside endometriomas would lead to the same type of genotoxic insult on gonadal endometrial implants. This would explain why endometriosis-associated cancers develop much more frequently in the ovary than at extragonadal sites. In women not seeking conception, bilateral salpingectomy could be advised whenever planning surgery for independent indications, thus possibly reducing cancer risk, while preserving ovarian function. The use of oral contraceptives should be favoured for prolonged periods of time, especially in women with endometriosis, a population at doubled risk of gonadal malignancy.

Assessing ovarian cancer risk when considering elective oophorectomy at the time of hysterectomy

OBJECTIVE

To develop a risk-factor score that may provide additional guidance to women and their physicians regarding elective bilateral salpingo-oophorectomy at the time of hysterectomy.

METHODS

From a case-control study conducted from 1992 to 2008 in women residing in eastern Massachusetts or New Hampshire, we selected 1,098 women with invasive ovarian cancer (case group) and 1,363 for the control group who were older than 40 years and had neither hysterectomy nor a personal or family history of breast or ovarian cancer. Using logistic regression, we identified key risk factors and built a risk score. The score was separately assessed in 126 women in the case group and 156 in the control group with excluded prior hysterectomy to determine whether women who developed ovarian cancer could have been distinguished.

RESULTS

Summing eight conditions found to be associated with ovarian cancer (Jewish ethnicity, less than 1 year of oral contraceptive use, nulliparity, no breastfeeding, no tubal ligation, painful periods or endometriosis, polycystic ovary syndrome or obesity, talc use), we created a five-level score. Assigning average risk to those with a score of 2, the odds ratios varied from 0.56 (95% confidence interval [CI] 0.42-0.74) for a score of 0-1 to 3.30 (95% CI 2.50-4.35) for a score of 5 or greater (P trend <.001). The risk score was higher for women who developed ovarian cancer after hysterectomy than those who did not (P=.01). Lifetime risks for ovarian cancer for a woman at age 40 years are changed from 1.2% with a 0-1 score to 6.6% with a score of 5 or higher.

CONCLUSION

We developed a risk-assessment tool that can quantify women's risk for ovarian cancer and should be validated in other data sets.

Circulating inflammation markers and risk of epithelial ovarian cancer

BACKGROUND

Factors contributing to chronic inflammation appear to be associated with increased risk of ovarian cancer. The purpose of this study was to assess the association between circulating levels of inflammation mediators and subsequent risk of ovarian cancer.

METHODS

We conducted a case-control study of 230 cases and 432 individually matched controls nested within three prospective cohorts to evaluate the association of prediagnostic circulating levels of inflammation-related biomarkers (IL-1β, IL-2, IL-4, IL-5, IL-6, IL-10, IL-12p40, IL-12p70, IL-13, TNFα, IL-1Ra, sIL-1RII, sIL-2Ra, sIL-4R, sIL-6R, sTNF-R1, and sTNF-R2) measured using Luminex xMap technology with risk of ovarian cancer.

RESULTS

We observed a trend across quartiles for IL-2 (OR(Q4 vs. Q1): 1.57, 95% CI: 0.98-2.52, P = 0.07), IL-4 (OR(Q4 vs. Q1): 1.50, 95% CI: 0.95-2.38, P = 0.06), IL-6 (OR(Q4 vs. Q1): 1.63, 95% CI: 1.03-2.58, P = 0.03), IL-12p40 (OR(Q4 vs. Q1): 1.60, 95% CI: 1.02-2.51, P = 0.06), and IL-13 (OR(Q4 vs. Q1): 1.42, 95% CI: 0.90-2.26, P = 0.11). Trends were also observed when cytokines were modeled on the continuous scale for IL-4 (P trend = 0.01), IL-6 (P trend = 0.01), IL-12p40 (P trend = 0.01), and IL-13 (P trend = 0.04). ORs were not materially different after excluding cases diagnosed less than 5 years after blood donation or when limited to serous tumors.

CONCLUSIONS AND IMPACT

This study provides the first direct evidence that multiple inflammation markers, specifically IL-2, IL-4, IL-6, IL-12, and IL-13, may be associated with risk of epithelial ovarian cancer, and adds to the evidence that inflammation is involved in the development of this disease.

High-Grade Serous Carcinoma Involving Fallopian Tube, Ovary and Peritoneum

The focus of this review is high-grade serous carcinoma (HGSC); for the purposes of this review, the term "pelvic SC" is used for HGSC that could be considered, based on historical definitions, to have arisen from ovary, fallopian tube, or peritoneum. These assignments of primary site are arbitrary and there is evidence that the distal fallopian tube is the site of origin of many pelvic HGSCs. The diagnosis of HGSC can be made readily based on routine histomorphologic examination in most cases; however, a variety of neoplasms can resemble HGSC. Thus, we review the key features of pelvic SC, current concepts of its pathogenesis, histopathological diagnostic criteria, discuss differential diagnosis, and review diagnostic ancillary studies that can be used in practice.

Molecular Pathology of Ovarian Carcinomas

This content presents a review of molecular pathology of ovarian cancer. The authors present key molecular features for high-grade and low-grade serous carcinomas, endometrioid carcinomas, clear cell carcinomas, and mucinous carcinomas. Cell lineage, mutation and gene expression, pathway alterations, risk factors, prognostic markers, and treatment targets are discussed.

Autofluorescence imaging can identify preinvasive or clinically occult lesions in fallopian tube epithelium: a promising step towards screening and early detection

BACKGROUND

Optical imaging systems are robust, portable, relatively inexpensive, and have proven utility in detecting precancerous lesions in the lung, esophagus, colon, oral cavity and cervix. We describe the use of light-induced endogenous fluorescence (autofluorescence) in identifying preinvasive and occult carcinomas in ex vivo samples of human fallopian tube (FT) epithelium.

METHODS

Women undergoing surgery for an i) ovarian mass, ii) a history suggestive of hereditary breast-ovarian cancer, or iii) known serous ovarian cancer following neoadjuvant chemotherapy (NAC) were approached for informed consent. Immediately following surgery, FT's were photographed in reflectance and fluorescence at high resolution. Images included: (1) white-light reflectance of luminal/epithelial surface; (2) narrow-band green reflectance (570 nm) (3) green autofluorescence (405/436 nm excitation); and (4) blue autofluorescence (405 nm excitation). Areas revealing a loss of natural tissue fluorescence or marked increase in tissue microvasculature were recorded and compared to final histopathologic diagnosis (SEE-FIM protocol).

RESULTS

Fifty-six cases involving one or both fallopian tubes underwent reflectance and fluorescence visualization. Nine cases were excluded, either secondary to non-ovarian primary pathology (7) or excessive trauma (2) rendering tissue interpretation impossible. Of the 47 cases remaining, there were 11 high grade serous (HGS) and 9 non-serous ovarian carcinomas undergoing primary debulking surgery, 5 serous carcinomas having received NAC, 8 benign ovarian tumors, and 14 women undergoing risk-reducing bilateral salpingo-oophorectomy (RRBSO). Methodology was feasible, efficient, and reproducible. TIC or carcinoma was identified in 7/11 HGS, 3/5 NAC, and 1/14 RRBSO. Optical images were reviewed to determine test positive or negative based on standardized criteria. Sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV) were calculated for the entire cohort (73%; 83%; 57%; 91%) and in a subgroup that excluded non-serous histology (87.5%; 92%; 78%; 96%).

CONCLUSIONS

Abnormal FT lesions can be identified using ex vivo optical imaging technologies. With this platform, we will move towards genomic interrogation of identified lesions, and developing in vivo screening modalities via falloposcopy.

Isolation and culture of ovarian cancer cells and cell lines

Ovarian carcinomas show considerable heterogeneity of origin, both in terms of site and tissue. The most important and also most frequent of these tumors arise from the coelomic epithelium and are therefore characterized as epithelial ovarian carcinomas (EOC). EOC is often large and advanced at the time of presentation, so that cells are readily obtainable from surgical specimens or effusions. While the primary tumor may be chemosensitive, they often develop resistance and may do so rapidly. Due to the easy access to tumor cells and its biological behavior, EOC is considered to be an ideal model to investigate principal mechanisms of both antineoplastic drug sensitivity and resistance. Although studies on primary EOC cells are now preferred for many of these investigations, EOC cell line studies remain important too. This chapter gives an overview over major techniques required to establish and maintain primary EOC cell cultures and to initiate and cultivate permanently growing EOC cell lines.

Fallopian tube origin of supposed ovarian high-grade serous carcinomas

INTRODUCTION

Serous carcinomas are the most frequent histologic type of ovarian and peritoneal cancers, and can also be detected in the endometrium and fallopian tubes. Serous carcinomas are usually high-grade neoplasms when diagnosed, yet the identification of an associated precursor lesion remains challenging. Pathological examination of specimens obtained from prophylactic bilateral salpingo-oophorectomies that were performed for patients harboring BRCA1/2 mutations suggests that high-grade serous carcinomas may arise in the fallopian tubes rather than in the ovaries.

OBJECTIVE

To investigate the presence and extent of fallopian tube involvement in cases of serous pelvic carcinomas.

METHODS

Thirty-four cases of serous pelvic carcinoma with clinical presentations suggesting an ovarian origin were analyzed retrospectively. Histologic samples of fallopian tube tissues were available for these cases and were analyzed. Probable primary site, type of tubal involvement, tissues involved in the neoplasia and vascular involvement were evaluated.

RESULTS

Fallopian tube involvement was observed in 24/34 (70.6%) cases. In 4 (11.8%) of these cases, an intraepithelial neoplasia was present, and therefore these cases were hypothesized to be primary from fallopian tubes. For an additional 7/34 (20.6%) cases, a fallopian tube origin was considered a possible primary.

CONCLUSIONS

Fallopian tubes can be the primary site for a subset of pelvic high-grade serous carcinomas.

Secretory cell outgrowth, PAX2 and serous carcinogenesis in the Fallopian tube

The 'p53 signature' is a benign secretory cell outgrowth in the distal Fallopian tube that shares properties with ovarian serous cancer-including p53 mutations-and is a putative serous cancer precursor. We expanded the precursor definition to all secretory cell outgrowths (SCOUTs) of 30 or more cells and scored normal (N) and altered (A) expression of both p53 and PAX2, a gene down-regulated in ovarian and endometrial cancer. SCOUTs were identified by BCL2/p73 staining in tubes from women with serous carcinoma, inherited mutations in BRCA1 or BRCA2 and controls. SCOUTs were prevalent in both proximal and distal tube and significantly associated with serous carcinoma versus the others (p < 0.001); 89% were PAX2 (A) and 26% were PAX2 (A)/p53 (A) (p53 signatures). PAX2 (A)/p53 (N) SCOUTs were free of p53 mutations; however, 12 of 13 p53 signatures were PAX2 (A). A tubal carcinoma and contiguous SCOUT were p53 (A)/PAX2 (A) and shared the same p53 mutation. SCOUTs are discretely localized alterations commonly containing altered expression of multiple genes within histologically benign tubal epithelium. Geographic distribution in the tube varies by genotype and immunophenotype, from regionally unrestricted (PAX2) to greater likelihood specific area (fimbria) of shared prevalence (PAX2 and p53). This study reveals, for the first time, an entity (SCOUT) that is associated with serous cancer, expands the topography of altered PAX2 expression in the female genital tract mucosa and highlights another potential pathway disturbance involved in early serous carcinogenesis in the Fallopian tube.

Differences in tumor type in low-stage versus high-stage ovarian carcinomas

Although there are recognized differences in the type of ovarian carcinomas between those tumors diagnosed at low versus high stage, there is a lack of data on stage distribution of ovarian carcinomas diagnosed according to the current histopathologic criteria from large population-based cohorts. We reviewed full slide sets of 1009 cases of 2555 patients diagnosed with ovarian carcinoma that were referred to the British Columbia Cancer Agency over a 16-year period (1984 to 2000). On the basis of the reviewed cases we extrapolated the distribution of tumor type in low-stage (I/II) and high-stage (III/IV) tumors. We then compared the frequencies with those seen in a large hospital practice. The overall frequency of tumor types was as follows: high-grade serous-68.1%, clear-cell-12.2%, endometrioid-11.3%, mucinous-3.4%, low-grade serous-3.4%, rare types-1.6%. High-grade serous carcinomas accounted for 35.5% of stage I/II tumors and 87.7% of stage III/IV tumors. In contrast, clear-cell (26.2% vs. 4.5%), endometrioid (26.6% vs. 2.5%), and mucinous (7.5% vs. 1.2%) carcinomas were relatively more common among the low-stage versus high-stage tumors. This distribution was found to be very similar in 410 consecutive cases from the Washington Hospital Center. The distribution of ovarian carcinoma types differs significantly in patients with low-stage versus high-stage ovarian carcinoma when contemporary diagnostic criteria are used, with consistent results seen in 2 independent case series. These findings reflect important biological differences in the behavior of the major tumor types, with important clinical implications.

The origin and pathogenesis of epithelial ovarian cancer: a proposed unifying theory

Ovarian cancer is the most lethal gynecologic malignancy. Efforts at early detection and new therapeutic approaches to reduce mortality have been largely unsuccessful, because the origin and pathogenesis of epithelial ovarian cancer are poorly understood. Despite numerous studies that have carefully scrutinized the ovaries for precursor lesions, none have been found. This has led to the proposal that ovarian cancer develops de novo. Studies have shown that epithelial ovarian cancer is not a single disease but is composed of a diverse group of tumors that can be classified based on distinctive morphologic and molecular genetic features. One group of tumors, designated type I, is composed of low-grade serous, low-grade endometrioid, clear cell, mucinous and transitional (Brenner) carcinomas. These tumors generally behave in an indolent fashion, are confined to the ovary at presentation and, as a group, are relatively genetically stable. They lack mutations of TP53, but each histologic type exhibits a distinctive molecular genetic profile. Moreover, the carcinomas exhibit a shared lineage with the corresponding benign cystic neoplasm, often through an intermediate (borderline tumor) step, supporting the morphologic continuum of tumor progression. In contrast, another group of tumors, designated type II, is highly aggressive, evolves rapidly and almost always presents in advanced stage. Type II tumors include conventional high-grade serous carcinoma, undifferentiated carcinoma, and malignant mixed mesodermal tumors (carcinosarcoma). They displayTP53 mutations in over 80% of cases and rarely harbor the mutations that are found in the type I tumors. Recent studies have also provided cogent evidence that what have been traditionally thought to be primary ovarian tumors actually originate in other pelvic organs and involve the ovary secondarily. Thus, it has been proposed that serous tumors arise from the implantation of epithelium (benign or malignant) from the fallopian tube. Endometrioid and clear cell tumors have been associated with endometriosis that is regarded as the precursor of these tumors. As it is generally accepted that endometriosis develops from endometrial tissue by retrograde menstruation, it is reasonable to assume that the endometrium is the source of these ovarian neoplasms. Finally, preliminary data suggest that mucinous and transitional (Brenner) tumors arise from transitional-type epithelial nests at the tubal-mesothelial junction by a process of metaplasia. Appreciation of these new concepts will allow for a more rationale approach to screening, treatment, and prevention that potentially can have a significant impact on reducing the mortality of this devastating disease.

Bcl-2 expression is altered with ovarian tumor progression: an immunohistochemical evaluation

Background

Ovarian cancer is the most lethal gynecologic malignancy. The ovarian tumor microenvironment is comprised of tumor cells, surrounding stroma, and circulating lymphocytes, an important component of the immune response, in tumors. Previous reports have shown that the anti-apoptotic protein Bcl-2 is overexpressed in many solid neoplasms, including ovarian cancers, and contributes to neoplastic transformation and drug-resistant disease, resulting in poor clinical outcome. Likewise, studies indicate improved clinical outcome with increased presence of lymphocytes. Therefore, we sought to examine Bcl-2 expression in normal, benign, and cancerous ovarian tissues to determine the potential relationship between epithelial and stromal Bcl-2 expression in conjunction with the presence of lymphocytes for epithelial ovarian tumor progression.

Methods

Ovarian tissue sections were classified as normal (n = 2), benign (n = 17) or cancerous (n = 28) and immunohistochemically stained for Bcl-2. Bcl-2 expression was assessed according to cellular localization, extent, and intensity of staining. The number of lymphocyte nests as well as the number of lymphocytes within these nests was counted.

Results

While Bcl-2 staining remained cytoplasmic, both percent and intensity of epithelial and stromal Bcl-2 staining decreased with tumor progression. Further, the number of lymphocyte nests dramatically increased with tumor progression.

Conclusion

The data suggest alterations in Bcl-2 expression and lymphocyte infiltration correlate with epithelial ovarian cancer progression. Consequently, Bcl-2 expression and lymphocyte status may be important for prognostic outcome or useful targets for therapeutic intervention.

Critical molecular abnormalities in high-grade serous carcinoma of the ovary

Ovarian carcinomas show more morphological heterogeneity than adenocarcinomas of any other body site. It has recently become clear that the morphologically defined subtypes of ovarian carcinoma are distinct diseases, with different risk factors, molecular events during oncogenesis, likelihood of spread, responses to chemotherapy, and outcomes. This review focuses on molecular abnormalities (in genes expressing BRCA1/2, TP53 and RB1/CCND1/CDKN2A/E2F) found in high-grade serous carcinomas of the ovary, which account for most ovarian cancer deaths. These highly aggressive but chemosensitive tumours are associated with perturbation of molecular pathways leading to genomic instability and extreme mutability and present unique challenges in oncological research and practice.