Clinical Characteristics of Clear Cell Ovarian Cancer: A Retrospective Multicenter Experience of 308 Patients in South Korea

Status and development of research on clear cell carcinoma of the ovary-a visualization-based bibliometric analysis

Background

Clear cell carcinoma of the ovary (CCCO) is a relatively rare type of epithelial ovarian cancer (EOC) that has unique biological characteristics and clinical features. Researchers have paid less attention to this disease than to other types of EOCs. However, in recent years, research in this area has still progressed. In this paper, a bibliometric analysis is used to integrate and analyse the literature in the field of CCCO in the past 20 years to determine research development, better understand the current status of research, and provide a reference for future study directions in this field.

Methods

With CCCO as the research subject, relevant publications indexed in the Web of Science (WOS) core dataset from September 2003 to September 2023 were retrieved. After screening the publications, we used EXCEL, VOSviewer, CiteSpace, Charticulator, Gephi, OriginPro and other tools to perform in-depth analyses of and to visualize the data.

Results

Through a comprehensive analysis of the literature in this field, we found that research on CCCO experienced a relatively rapid increase in 2006 and is now in a period of relatively high fluctuation. The quality of the literature in this field is generally high. In this field, countries in East Asia and North America play core roles, with Japan accounting for the most studies. A stable research group has been formed in this field, and extensive collaboration has occurred among the various research groups. In the past 20 years, basic research and clinical research in the field of CCCO have developed together, and a healthy development model in which basic and clinical research promote each other has formed. Research in this field has been continuously developed from a preliminary understanding of clinical features to in-depth explorations of the pathogenesis and the continuous optimization of treatment methods. The key molecular events in the pathogenesis and development of this disease and the application of novel antitumour drugs for this disease are the current research focuses and the future development direction in this field.

Conclusions

Research on CCCO has progressed significantly in the past 20 years, but there are still many important issues regarding its pathogenesis and treatment that need to be addressed, and therefore, more research in this area should be conducted in the future. The study of key molecular events and the use of novel antitumour drugs are future development directions in this field.

From clinical management to personalized medicine: novel therapeutic approaches for ovarian clear cell cancer

Ovarian clear-cell cancer is a rare subtype of epithelial ovarian cancer with unique clinical and biological features. Despite optimal cytoreductive surgery and platinum-based chemotherapy being the standard of care, most patients experience drug resistance and a poor prognosis. Therefore, novel therapeutic approaches have been developed, including immune checkpoint blockade, angiogenesis-targeted therapy, ARID1A synthetic lethal interactions, targeting hepatocyte nuclear factor 1β, and ferroptosis. Refining predictive biomarkers can lead to more personalized medicine, identifying patients who would benefit from chemotherapy, targeted therapy, or immunotherapy. Collaboration between academic research groups is crucial for developing prognostic outcomes and conducting clinical trials to advance treatment for ovarian clear-cell cancer. Immediate progress is essential, and research efforts should prioritize the development of more effective therapeutic strategies to benefit all patients.

Application of precision medicine based on next-generation sequencing and immunohistochemistry in ovarian cancer: a real-world experience

OBJECTIVE

To evaluate the landscape of gene alterations and immunohistochemistry (IHC) profiles of patients with ovarian cancer for targeted therapy and investigate the real-world experience of applying precision medicine.

METHODS

Patients diagnosed with ovarian cancer between January 2015 and May 2021 at Severance Hospital and who underwent tumor next-generation sequencing (NGS) were reviewed. Data on germline mutation, IHC markers for mismatch repair deficiency (MMRd), programmed death ligand 1 (PD-L1) expression, and human epidermal growth factor receptor 2 (HER2) expression were acquired. The use of matched therapy and its clinical outcomes were evaluated.

RESULTS

Of the 512 patients who underwent tumor NGS, 403 underwent panel-based germline testing. In patients who underwent both tests, tumor NGS identified 39 patients (9.7%) with BRCA mutations and 16 patients (4.0%) with other homologous recombination repair (HRR)-associated gene mutations, which were not found in germline testing. The most common single nucleotide variants were TP53 (82.2%), ARID1A (10.4%), PIK3CA (9.7%), and KRAS (8.4%). Copy number aberrations were found in 122 patients. MMRd was found in 3.2% of patients, high PD-L1 expression in 10.1%, and HER2 overexpression in 6.5%. Subsequently, 75 patients (14.6%) received a poly (ADP-ribose) polymerase inhibitor based on BRCA mutation and 11 patients (2.1%) based on other HRR-associated gene mutations. Six patients (1.2%) with MMRd underwent immunotherapy. Twenty-eight patients (5.5%) received other matched therapies targeting HER2, fibroblast growth factor receptor, folate receptor alpha, RAS, and PIK3CA.

CONCLUSION

A comprehensive review of germline mutation, IHC, and tumor NGS helped identify candidates for precision therapy in patients with ovarian cancer, a proportion of whom received matched therapy.

Clinical perspectives of rare ovarian tumors: clear cell ovarian cancer

Ovarian clear cell carcinoma (OCCC) is a rare and distinct histological type of epithelial ovarian carcinoma in terms of its histopathological, clinical and genetic features. Patients with OCCC are younger and diagnosed at earlier stages than those with the most common histological type-high-grade serous carcinoma. Endometriosis is considered a direct precursor of OCCC. Based on preclinical data, the most frequent gene alternations in OCCC are mutations of AT-rich interaction domain 1A and phosphatidylinositol-4,5-bisphosphate 3-kinase catalytic subunit alpha. The prognosis of patients with early-stage OCCC is favorable, whereas patients at an advanced stage or who have the recurrent disease have a dismal prognosis due to OCCC's resistance to standard platinum-based chemotherapy. Despite a lower rate of response due to its resistance to standard platinum-based chemotherapy, the treatment strategy for OCCC resembles that of high-grade serous carcinoma, which includes aggressive cytoreductive surgery and adjuvant platinum-based chemotherapy. Alternative treatment strategies, including biological agents based on molecular characteristics specific to OCCC, are urgently needed. Furthermore, due to its rarity, well-designed collaborative international clinical trials are needed to improve oncologic outcomes and the quality of life in patients with OCCC.

Clear cell carcinoma of the ovary and venous thromboembolism: a systematic review and meta-analysis

OBJECTIVES

As the second most common subtype of Epithelial ovarian cancers (EOCs), ovarian clear cell carcinoma (OCCC) is associated with a high rate of cancer-associated thrombosis. Previous studies revealed the wide range prevalence (6-42%) of venous thromboembolism (VTE) among OCCC patients. This study aimed to determine the prevalence of VTE among OCCC patients as well as factors affecting it.

METHODS

PubMed, Scopus, Embase, and Cochrane Library databases were searched up to December 12th, 2022. Studies reporting venous thromboembolic events in women with clear cell carcinoma of the ovary were included. Demographic data, clinical, and paraclinical features of the patients were independently extracted by two reviewers.

RESULTS

Out of the 2254 records, 43 studies were processed for final review. The qualified studies involved 573 VTE cases among 2965 patients with OCCC. The pooled prevalence of VTE among OCCC patients was 21.32% (95%CI=(17.38-25.87)). Most VTE events were reported in Japanese women (26.15%), followed by Americans (24.41%) and UK (21.57%), and Chinese (13.61%) women. VTE was more common in patients with advanced stages (37.79%) compared to those with early stages of the disease (16.54%).

CONCLUSIONS

Ovarian clear cell carcinoma is associated with a high rate of cancer-associated thrombosis. VTE events in OCCC patients were higher in advanced stages and Japanese women.

The Significance of Radiotherapy in Ovarian Clear Cell Carcinoma: A Systematic Review and Meta-Analysis

OBJECTIVE

To assess the response rate and survival effect of adjuvant radiotherapy (RT) or chemoradiotherapy (CRT) during ovarian clear cell carcinoma (OCCC).

METHODS

We searched Web of Science, PubMed, Cochrane library electronic databases, Clinical Trials, WanFang Data and Chinese National Knowledge Infrastructure (CNKI) up to October 2022. We also searched registers of clinical trials, abstracts of scientific meetings and reference lists of included studies.

RESULTS

We identified a total of 4259 patients from 14 studies met the inclusion criteria. The pooled response rate of residual tumors for RT/CRT was 80.0%, the pooled 5-year progression-free survival (PFS) ratio during RT/CRT group was 61.0%, and the pooled 5-year overall survival (OS) ratio during RT/CRT group was 68.0%; heterogeneity tests demonstrated significant difference between studies (I² >50%). Cumulative results suggested adjuvant RT/CRT improved 5-year PFS ratio of OCCC patients (OR: 0.51 (95% CI: 0.42-.88), I² = 22%, P = .009), had no impact on 5-year OS ratio (OR: 0.52 (95% CI: 0.19-1.44), I² = 87%, P = .21); meta-regression of studies before and after 2000 found consistent results. Sub-analysis observed that adjuvant RT/CRT had no impact on 5-year OS ratio of early-stage (stage I + II) OCCC patients (OR: 0.67 (95% CI: 0.25-1.83), I² = 85%, P = .44), but might improve 5-year OS ratio of advanced and recurrent OCCC patients (OR: 0.13(95% CI: 0.04-.44), P = .001).

CONCLUSION

This analysis suggested that adjuvant RT/CRT might improve oncologic outcomes of OCCC, especially for advanced and recurrent cases. Due to the inherent selective biases of retrospective studies enrolled in the meta-analysis, more convincing evidences based on prospective randomized controlled trials (RCTs) are urgently needed.

Patients with stage IA ovarian clear cell carcinoma do not require chemotherapy following surgery

BACKGROUND

Ovarian clear cell carcinoma (OCCC) is an infrequent histological subtype of epithelial ovarian cancer (EOC). The present study aimed to investigate whether chemotherapy is indispensable for patients with stage IA OCCC.

METHODS

Data were collected from the Surveillance, Epidemiology and End Results database between 2004 and 2015. All subjects were diagnosed with stage IA OCCC, according to their postoperative pathological reports. In the present study, 1038 patients were retrospectively investigated, among whom 692 patients received chemotherapy. Propensity score matching (PSM) was performed to prevent selection bias. The multivariate Cox proportional hazards model was used to analyze the correlation between variables and 5-year overall survival.

RESULTS

An equal number of patients (n = 346) who did or did not undergo chemotherapy after PSM were further enrolled in the study. The results showed that the mortality of OCCC increased for the patients aged ≥50 years. In addition, older age was associated with lower 5-year overall survival (p < 0.05). However, chemotherapy did not extend the 5-year overall survival (p = 0.524) of patients with stage IA OCCC, according to the multivariate Cox regression analysis.

CONCLUSIONS

Chemotherapy did not affect the overall survival of patients with stage IA OCCC following surgery.

Clinical analysis and literature review of a case of ovarian clear cell carcinoma with PIK3CA gene mutation: A case report

RATIONALE

Ovarian clear cell carcinoma (OCCC) is an uncommon malignant form of 5 subtypes of ovarian cancer, accounting for approximately 5% to 25% of all ovarian cancers. OCCC is usually diagnosed at a young age and an early stage. More than 50% of patients are associated with endometriosis. It shows less sensitivity to platinum-based chemotherapies, high recurrence, and poor prognosis, especially late. However, platinum-based chemotherapies remain the first-line treatment. Meanwhile, new treatment modalities have been explored, including immune checkpoint inhibitors and PI3K-AKT-mTOR pathway inhibitors.

PATIENT CONCERN

A 48-year-old Chinese woman, Gravida2 Para1, complained of irregular and painful vaginal bleeding for 4 months.

DIAGNOSIS

The patient was diagnosed with stage IC ovarian clear cell carcinoma that presented with a mutation of the phosphatidylinositol 4,5-bisphosphate 3-kinase alpha subunit (PIK3CA) gene.

INTERVENTION

We performed an early diagnosis and complete surgical resection of the tumor with platinum-based chemotherapy.

OUTCOME

This patient with mutation of the PIK3CA gene was sensitive to platinum-based chemotherapy, showed a significant downwards trend in tumor markers, and was in good health within the year of follow-up.

LESSONS

This study described an OCCC case that presented with a PIK3CA mutation and was successfully managed with careful and complete resection of the tumor. This patient with mutation of the PIK3CA gene was sensitive to platinum-based chemotherapy, showed a significant downwards trend in tumor markers, and did not have recurrence after a year of follow-up, indicating a reasonably good prognosis. Therefore, surgery plus platinum drug chemotherapy is still the best strategy for OCCC treatment. In addition, it is recommended for such patients to undergo genetic testing as much as possible to predict the clinical treatment effect.

Friend or foe? The prognostic role of endometriosis in women with clear cell ovarian carcinoma. A UK population-based cohort study

PURPOSE

The prognostic role of endometriosis amongst women with ovarian clear cell carcinoma (OCCC) remains debatable. The aim of this study was to ascertain the effect of endometriosis on the prognosis of OCCC.

METHODS

A retrospective review of the medical records of 94 women diagnosed and treated for OCCC at a tertiary gynaecological cancer centre in the UK, spanning the period 2010-2019. Women were divided into two groups according to the presence of endometriosis. Clinico-pathological characteristics, progression-free survival (PFS) and overall survival (OS) were collated between the two groups.

RESULTS

Forty-six cases of endometriosis-free OCCC (Ef-OCCC) were collated with 48 cases of endometriosis-related OCCC (Er-OCCC). There was no significant difference between the two groups regarding age (p-value = 0.2), FIGO stage (p-value = 0.8), residual disease (RD) (p-value = 0.07), adjuvant chemotherapy agent (p-value = 0.4) or chemo-resistance (p-value = 0.9). The presence of endometriosis did not significantly affect either OS or PFS. The median OS in the Ef-OCCC and Er-OCCC was 55.00 (95% CI 32.00-189.00) and 71.00 (95% CI 47.00-97.00; log rank = 1.35, p-value = 0.2) months. The median PFS in the Ef-OCCC and Er-OCCC group was 39.00 (95% CI 19.00-143.00) and 39.00 (95% CI 19.00-62.00; log rank = 0.7, p-value = 0.4) months. Survival differences between the two groups were not significant after stratification analysis for independent prognosticators.

CONCLUSION

Endometriosis was not independently associated with the prognosis of OCCC either in crude analysis or after stratification for stage and RD. Further larger, well-designed prospective studies are warranted to draw firmer conclusions on the intrinsic link between endometriosis and OCCC.

Association Between Endometriosis and Prognosis of Ovarian Cancer: An Updated Meta-Analysis

Objective

Increased risk of ovarian cancer (OC) among endometriosis patients has been proposed. However, the association between endometriosis and prognosis of OC remains controversial. This study evaluated whether endometriosis had influence on the survival outcomes of OC through a meta-analysis.

Methods

Relevant studies were retrieved from PubMed, Embase, and Web of Science databases and were evaluated using the Newcastle-Ottawa Quality Assessment Scale. Effect size was presented as hazard ratio (HR) and 95% confidence interval (CI). Heterogeneity test evaluation was performed using Cochran’s Q test and I2 statistics. Publication bias was determined using Egger’s test. Statistical analysis was performed using Stata 12.0 software.

Results

Twenty-one studies involving 38641 patients were included. For the total OC, there were significant differences in overall survival (OS) [HR (95% CI)=0.67 (0.55, 0.80), P&lt;0.001] and progression-free survival (PFS) [HR (95% CI)=0.58 (0.42, 0.81), P=0.001] between endometriosis-associated ovarian cancer (EAOC) and non-EAOC patients in the random-effects models (P&lt;0.05). For ovarian clear cell cancer, there were significant differences in terms of OS [HR (95% CI)=0.63 (0.48, 0.83), P=0.001] and PFS [HR (95% CI)=0.67 (0.52, 0.87), P=0.002] between EAOC and non-EAOC patients in the fixed-effects models (P&gt;0.05). Subgroup analysis suggested no significant differences between EAOC and non-EAOC in OS and PFS in the univariate analysis per subgroup, and PFS in the American subgroup (P&gt;0.05).

Conclusion

EAOC patients tended to have better OS and PFS than non-EAOC patients. Conducting higher quality prospective cohort studies with large sample sizes is recommended to confirm the authenticity of the current study’s results.

Systematic Review Registration

https://inplasy.com/inplasy-2022-3-0109/.

Endometriosis-associated Ovarian Clear Cell Carcinoma: A Special Entity?

Endometriosis is an estrogen-dependent disease, which serves as a precursor of ovarian cancer, especially clear cell carcinoma (OCCC) and endometrial carcinoma. Although micro-environmental factors such as oxidative stress, immune cell dysfunction, inflammation, steroid hormones, and stem cells required for malignant transformation have been found in endometriosis, the exact carcinogenic mechanism remains unclear. Recent research suggest that many putative driver genes and aberrant pathways including ARID1A mutations, PIK3CA mutations, MET activation, HNF-1β activation, and miRNAs dysfunction, play crucial roles in the malignant transformation of endometriosis to OCCC. The clinical features of OCCC are different from other histological types. Patients usually present with a large, unilateral pelvic mass, and occasionally have thromboembolic vascular complications. OCCC patients are easier to be resistant to chemotherapy, have a worse prognosis, and are usually difficult to treat. To improve the survival of OCCC patients, it is necessary to better understand its specific carcinogenic mechanism and explore new treatment strategy, including molecular target.

A CLEARER VIEW ON OVARIAN CLEAR CELL CARCINOMA

Introduction: Ovarian clear cell carcinoma (OCCC) is a less common subtype accounting for approximately 5% of all epithelial ovarian cancers (EOCs). Clinical experience and research findings confirm the remarkable differences in clinical behavior, molecular alterations and pathogenesis of OCCC. The diagnosis of OCCC is typically set at a younger age, and earlier stage and in a background of endometriosis.Results: Molecularly, OCCCs rarely harbor BRCA1/BRCA2 mutations and have fewer copy number variants (CNVs). The most common molecular changes occur in the SWI/SNF chromatin remodeling complex genes, the PI3K/AKT signaling pathway and the receptor tyrosine kinase (RTK)/Ras signaling pathway.Five-year disease-specific survival of patients with OCCC is worse compared to high grade serous carcinomas (HGSOC). The current treatment options for OCCC are based on studies that included patients with predominantly HGSOC and only a minor proportion of cancers with clear cell histology. In order to improve outcomes for patients with OCCC, research should be specific for this subtype.Discussion: As the available information about the specific characteristics of OCCC is increasing, especially at a molecular level, it should be possible to continuously improve the specific diagnostics and treatment. Since OCCC is so rare, it is essential to collect new evidence at an international level. To avoid extrapolation from EOC trials with possible erroneous conclusions, patients should always be encouraged to participate in specific histological trials and basket trials, while paying extra attention to OCCC-like subtypes.

Clinical characteristics and prognosis of ovarian clear cell carcinoma: a 10-year retrospective study

Background

Ovarian clear cell carcinoma (OCCC) is a special pathological type of epithelial ovarian carcinoma (EOC). We conducted this research to investigate the clinical characteristics and outcomes of OCCC and to provide additional supporting evidence to aid in the clinical diagnosis and management.

Methods

This was a retrospective study investigating the clinical characteristics and survival outcomes of 86 patients with OCCC treated at our center between January 2010 and March 2020. Survival analysis was also performed on 179 patients with OCCC obtained from the Surveillance, Epidemiology and End Results (SEER) cancer registry database.

Results

The median age of participants was 49.21 ± 9.91 years old, and 74.42% of them were diagnosed at early stage. The median CA125 level was 601.48 IU/mL, while 19.77% of the patients had normal CA125 levels. Sixteen patients (18.60%) had co-existing endometriosis and 8 patients (9.3%) developed venous thromboembolism (VTE). There were 5 patients received suboptimal cytoreduction. Sixty-six patients (76.74%) underwent lymphadenectomy, and only 3 (4.55%) patients had positive lymph nodes. Patients diagnosed at an early stage had higher 3-year overall survival (OS) and progression-free survival (PFS) rates than those with advanced stage OCCC. CA19–9 (P = 0.025) and ascites (P = 0.001) were significantly associated with OS, while HE4 (P = 0.027) and ascites (P = 0.001) were significantly associated with PFS. Analysis of data from the SEER database showed that positive lymph nodes is also an independent prognostic factor for OS (P = 0.001).

Conclusions

OCCC often presents at an early stage and young age with a mildly elevated CA125. CA19–9, HE4, massive ascites, and positive lymph node are independent prognostic factors.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12885-021-08061-7.

Updates of Pathogenesis, Diagnostic and Therapeutic Perspectives for Ovarian Clear Cell Carcinoma

Ovarian clear cell carcinoma (OCCC) is a special pathological type of epithelial ovarian carcinoma (EOC) and has a high prevalence in Asia without specific molecular subtype classification. Endometriosis is a recognized precancerous lesion that carries 3-fold increased risk of OCCC. Ovarian endometrioid carcinoma, which also originates from endometriosis, shares several features with OCCC, including platinum resistance and younger age at diagnosis. Patients with OCCC have about a 2.5 to 4 times greater risk of having a venous thromboembolism (VTE) compared with other EOC, and OCCC tends to metastasize through lymphatic vesicular and peritoneal spread as opposed to hematogenous metastasis. There is only mild elevation of the conventional biomarker CA125. Staging surgery or optimal cytoreduction combined with chemotherapy is a common therapeutic strategy for OCCC. However, platinum resistance commonly portends a poor prognosis, so novel treatments are urgently needed. Targeted therapy and immunotherapy are currently being studied, including PARP, EZH2, and ATR inhibitors combined with the synthetic lethality of ARID1A-dificiency, and MAPK/PI3K/HER2, VEGF/bFGF/PDGF, HNF1β, and PD-1/PD-L1 inhibitors. Advanced stage, suboptimal cytoreduction, platinum resistance, lymph node metastasis, and VTE are major prognostic predictors for OCCC. We focus on update pathogenesis, diagnostic methods and therapeutic approaches to provide future directions for clinical diagnosis and treatment of OCCC.

An exploratory analysis about cycles of adjuvant chemotherapy and outcomes by substage for stage I ovarian clear cell carcinoma: a single institution retrospective study

This retrospective cohort study was designed to explore the prognostic impact of adjuvant chemotherapy and tumor substage on stage I ovarian clear cell carcinoma (OCCC). Data of 102 patients with stage I OCCC who underwent surgery at the National Cancer Center/Cancer Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College from February 1999 to December 2018 was retrospectively analyzed. Prognostic factors were evaluated using the Cox Regression Model. The disease-free survival (DFS) and overall survival (OS) were assessed by the Kaplan-Meier method and compared between different groups with the log-rank test. P < 0.05 was considered statistically significant. The median follow-up duration was 40.5 months. Thirty-one (30.4%) patients were at stage IA, and 17 (16.7%), 5 (24.5%) and 17 (16.7%) patients were at stage IC1, IC2 and IC3 respectively. The 5-year and 10-year DFS rates of the entire cohort were 82.8% and 78.8% respectively, and the 5-year OS was 97.9%. Patients at stages ICI (intraoperatively ruptured tumor) and IA had similar DFS (P=0.538, OR=0.024), and that of patients at stages IC2 (tumor ruptured preoperatively or tumor on ovarian surface) or IC3 (ascites or peritoneal washings with positive cytology) was significantly lower (72.6% vs. 95.1%, P=0.039, OR=5.051). The 5-year DFS of patients receiving four (83.9%) and more than four (81.7%) cycles adjuvant chemotherapy were similar. Furthermore, univariate analysis showed that age, tumor size and CA199 levels were significantly correlated with DFS, although none of these variables were identified as independent prognostic factors in the multivariate analysis. In summary, our results suggest that patients with stage I OCCC have overall good prognosis. However, tumor surface involvement or positive cytology can worsen prognosis, and the prognosis may not be improved by more than four cycles chemotherapy following surgery. The remarkable increased CA199 may be a potential indicator of poor prognosis in stage I OCCC.

Development and validation of Nomograms for predicting overall survival and Cancer-specific survival in patients with ovarian clear cell carcinoma

BACKGROUND

Ovarian clear cell carcinoma (OCCC) is a rare histologic type of ovarian cancer. There is a lack of an efficient prognostic predictive tool for OCCC in clinical work. This study aimed to construct and validate nomograms for predicting the overall survival (OS) and cancer-specific survival (CSS) in patients with OCCC.

METHODS

Data of patients with primary diagnosed OCCC in the Surveillance, Epidemiology, and End Results (SEER) database between 2010 and 2016 was extracted. Prognostic factors were evaluated with LASSO Cox regression and multivariate Cox regression analysis, which were applied to construct nomograms. The performance of the nomogram models was assessed by the concordance index (C-index), calibration plots, decision curve analysis (DCA) and risk subgroup classification. The Kaplan-Meier curves were plotted to compare survival outcomes between subgroups.

RESULTS

A total of 1541 patients from SEER registries were randomly divided into a training cohort (n = 1079) and a validation cohort (n = 462). Age, laterality, stage, lymph node (LN) dissected, organ metastasis and chemotherapy were independently and significantly associated with OS, while laterality, stage, LN dissected, organ metastasis and chemotherapy were independent risk factors for CSS. Nomograms were developed for the prediction of 3- and 5-year OS and CSS. The C-indexes for OS and CSS were 0.802[95% confidence interval (CI) 0.773-0.831] and 0.802 (0.769-0.835), respectively, in the training cohort, while 0.746 (0.691-0.801) and 0.770 (0.721-0.819), respectively, in the validation cohort. Calibration plots illustrated favorable consistency between the nomogram predicted and actual survival. C-index and DCA curves also indicated better performance of nomogram than the AJCC staging system. Significant differences were observed in the survival curves of different risk subgroups.

CONCLUSIONS

We have constructed predictive nomograms and a risk classification system to evaluate the OS and CSS of OCCC patients. They were validated to be of satisfactory predictive value, and could aid in future clinical practice.

Clear cell carcinoma of the ovary: a clinical and molecular perspective

Clear cell carcinoma of the ovary has distinct biology and clinical behavior. There are significant geographical and racial differences in the incidence of clear cell carcinoma compared with other epithelial ovarian tumors. Patients with clear cell carcinoma are younger, tend to present at an early stage, and their tumors are commonly associated with endometriosis, which is widely accepted as a direct precursor of clear cell carcinoma and has been identified pathologically in approximately 50% of clear cell carcinoma cases. The most frequent and important specific gene alterations in clear cell carcinoma are mutations of AT-rich interaction domain 1A (ARID1A) (~50% of cases) and phosphatidylinositol-4,5-bisphosphate 3-kinase catalytic subunit alpha (PIK3CA) (~50% cases). More broadly, subgroups of clear cell carcinoma have been identified based on C-APOBEC (apolipoprotein B mRNA editing enzyme, catalytic polypeptide-like) and C-AGE (age-related) mutational signatures. Gene expression profiling shows upregulation of hepatocyte nuclear factor 1-beta (HNF1β) and oxidative stress-related genes, and has identified epithelial-like and mesenchymal-like tumor subgroups. Although the benefit of platinum-based chemotherapy is not clearly defined it remains the mainstay of first-line therapy. Patients with early-stage disease have a favorable clinical outcome but the prognosis of patients with advanced-stage or recurrent disease is poor. Alternative treatment strategies are required to improve patient outcome and the development of targeted therapies based on molecular characteristics is a promising approach. Improved specificity of the histological definition of this tumor type is helping these efforts but, due to the rarity of clear cell carcinoma, international collaboration will be essential to design appropriately powered, large-scale clinical trials.