Clear cell cancer of the uterine corpus: the association of clinicopathologic parameters and treatment on disease progression

Single-cell RNA sequencing in endometrial cancer: exploring the epithelial cells and the microenvironment landscape

Single-cell RNA sequencing (scRNA-seq) technology has emerged as a powerful tool for dissecting cellular heterogeneity and understanding the intricate biology of diseases, including cancer. Endometrial cancer (EC) stands out as the most prevalent gynecological malignancy in Europe and the second most diagnosed worldwide, yet its cellular complexity remains poorly understood. In this review, we explore the contributions of scRNA-seq studies to shed light on the tumor cells and cellular landscape of EC. We discuss the diverse tumoral and microenvironmental populations identified through scRNA-seq, highlighting the implications for understanding disease progression. Furthermore, we address potential limitations inherent in scRNA-seq studies, such as technical biases and sample size constraints, emphasizing the need for larger-scale research encompassing a broader spectrum of EC histological subtypes. Notably, a significant proportion of scRNA-seq analyses have focused on primary endometrioid carcinoma tumors, underscoring the need to incorporate additional histological and aggressive types to comprehensively capture the heterogeneity of EC. By critically evaluating the current state of scRNA-seq research in EC, this review underscores the importance of advancing towards more comprehensive studies to accelerate our understanding of this complex disease.

Range of Resection in Endometrial Cancer-Clinical Issues of Made-to-Measure Surgery

Endometrial cancer (EC) poses a significant health issue among women, and its incidence has been rising for a couple of decades. Surgery remains its principal treatment method and may have a curative, staging, or palliative aim. The type and extent of surgery depends on many factors, and the risks and benefits should be carefully weighed. While simple hysterectomy might be sufficient in early stage EC, modified-radical hysterectomy is sometimes indicated. In advanced disease, the evidence suggests that, similarly to ovarian cancer, optimal cytoreduction improves survival rate. The role of lymphadenectomy in EC patients has long been a controversial issue. The rationale for systematic lymphadenectomy and the procedure of the sentinel lymph node biopsy are thoroughly discussed. Finally, the impact of the molecular classification and new International Federation of Gynecology and Obstetrics (FIGO) staging system on EC treatment is outlined. Due to the increasing knowledge on the pathology and molecular features of EC, as well as the new advances in the adjuvant therapies, the surgical management of EC has become more complex. In the modern approach, it is essential to adjust the extent of the surgery to a specific patient, ensuring an optimal, made-to-measure personalized surgery. This narrative review focuses on the intricacies of surgical management of EC and aims at summarizing the available literature on the subject, providing an up-to-date clinical guide.

Preoperative hysteroscopy shortened progression-free survival in advanced FIGO stage in endometrial cancer: Ten year analysis

OBJECTIVE

To investigate the impact of preoperative hysteroscopy on progression-free survival (PFS) and disease-specific survival (DFS), and to explore the factors which contribute to poor clinical outcomes between hysteroscopy and dilation and curettage (D&C) in endometrial cancer (EC).

METHODS

A retrospective study was designed by collecting data from women diagnosed with EC through hysteroscopy or D&C from January 2010 to December 2019 in a tertiary hospital in China. A propensity score was used for 1:1 matching of advanced stage patients. Univariate and multivariate analysis were conducted to determine whether hysteroscopy was a prognostic factor in EC and to identify factors associated with its impact on PFS and DFS in different subgroups.

RESULTS

Overall, 543 and 272 women who underwent D&C and hysteroscopy, respectively were included. Compared to D&C, preoperative hysteroscopy was related to reduced PFS and DFS, with a hazard ratio (HR) of 1.904 and 3.905, respectively. Hysteroscopy contributed to an increased risk of positive wash cytology (48.27% vs 24.13%), recurrence (48.28% vs 20.69%) and shorter PFS after matching in FIGO Stage I-IV EC, while there was no significance in positive ascites cytology (14.04% vs 13.45%), PFS and DFS in FIGO Stage I EC.

CONCLUSIONS

Hysteroscopy was an independent predictive factor for poor prognosis in EC. Hysteroscopy appeared to be a safe diagnostic method as D&C in FIGO Stage I EC but was a risk factor for increased recurrence and reduced PFS in advanced stage disease. Its impact on DFS is uncertain.

SEOM-GEICO clinical guidelines on endometrial cancer (2021)

Endometrial cancer (EC) is the second most common gynecological malignancy worldwide, the first in developed countries [Sung et al. in CA Cancer J Clin 71:209–249, 2021]. Although a majority is diagnosed at an early stage with a low risk of relapse, an important proportion of patients will relapse. Better knowledge of molecular abnormalities is crucial to identify high-risk groups in early stages as well as for recurrent or metastatic disease for whom adjuvant treatment must be personalized. The objective of this guide is to summarize the current evidence for the diagnosis, treatment, and follow-up of EC, and to provide evidence-based recommendations for clinical practice.

Prognostic factors in clear cell carcinoma of endometrium: analysis of 55 cases

BACKGROUND AND AIM OF THE WORK

The purpose of this study was to evaluate the clinical and pathologic prognostic factors associated with survival in patients with clear cell carcinoma (CCC) of the endometrium.

METHODS

A retrospective review of fifty-five patients with endometrial clear cell carcinoma were collected.

RESULTS

The median overall and disease-free survivals were 40 and 20 months, respectively. A univariate analysis was performed with respect to stage of disease, age, lymph nodes status, myometrium invasion, lymph vascular space invasion and adjuvant therapy. Stage was found to be the only important prognostic factor related to survival. In fact, early stage had a median survival of 77 months compared to 34 months in the advanced disease (p<0.04). These differences remained significant after adjusting for single stage (stage III versus IV).    Conclusions: Endometrial CCC is a rare histotype. Advanced stage disease is considered a poor prognostic factor. Recurrences are high even in early stage. Randomized clinical trials are needed.

Multidrug efflux transporter ABCG2: expression and regulation

The adenosine triphosphate (ATP)-binding cassette efflux transporter G2 (ABCG2) was originally discovered in a multidrug-resistant breast cancer cell line. Studies in the past have expanded the understanding of its role in physiology, disease pathology and drug resistance. With a widely distributed expression across different cell types, ABCG2 plays a central role in ATP-dependent efflux of a vast range of endogenous and exogenous molecules, thereby maintaining cellular homeostasis and providing tissue protection against xenobiotic insults. However, ABCG2 expression is subjected to alterations under various pathophysiological conditions such as inflammation, infection, tissue injury, disease pathology and in response to xenobiotics and endobiotics. These changes may interfere with the bioavailability of therapeutic substrate drugs conferring drug resistance and in certain cases worsen the pathophysiological state aggravating its severity. Considering the crucial role of ABCG2 in normal physiology, therapeutic interventions directly targeting the transporter function may produce serious side effects. Therefore, modulation of transporter regulation instead of inhibiting the transporter itself will allow subtle changes in ABCG2 activity. This requires a thorough comprehension of diverse factors and complex signaling pathways (Kinases, Wnt/β-catenin, Sonic hedgehog) operating at multiple regulatory levels dictating ABCG2 expression and activity. This review features a background on the physiological role of transporter, factors that modulate ABCG2 levels and highlights various signaling pathways, molecular mechanisms and genetic polymorphisms in ABCG2 regulation. This understanding will aid in identifying potential molecular targets for therapeutic interventions to overcome ABCG2-mediated multidrug resistance (MDR) and to manage ABCG2-related pathophysiology.

Role of cancer stem cell markers ALDH1, BCL11B, BMI-1, and CD44 in the prognosis of advanced HNSCC

Purpose

Cancer stem cells (CSCs) are held accountable for the progress of head and neck squamous cell carcinoma (HNSCC). In the presented study, the authors evaluated the prognostic value of CSC markers in two particular HNSCC cohorts.

Methods

This two cohort study consisted of 85 patients with advanced stage HNSCC, treated with primary radio(chemo)therapy (pRCT), and 95 patients with HNSCC, treated with surgery and partially adjuvant radio(chemo)therapy. Overall survival (OS), disease-free survival (DFS), and disease-specific survival (DSS) were assessed. Samples were assessed for the expression of different molecular stem cell markers (ALDH1, BCL11B, BMI‑1, and CD44).

Results

In the pRCT cohort, none of the baseline patient and tumor features exhibited a statistically significant relation with survival in either the cohort or the human papillomavirus (HPV)-stratified subcohorts. High expression of BMI‑1 significantly decreased OS and DFS, while high expression of CD44 decreased all modes of survival. Multivariate analysis showed significant prognostic influence for all tested CSC markers, with high BMI‑1 and CD44 decreasing survival (BMI-1: OS, DFS, DSS; CD44: OS, DFS) and high ALDH1 and BCL11B showing a beneficial effect on survival (ALDH1: OS, DFS; BCL11B: OS, DSS). In the surgical cohort, classical prognosticators such as HPV status, R1 resection, and nodal status in HPV-negative HNSCC played a significant role, but the tested CSC markers showed no significant effect on prognosis.

Conclusion

Although validation in independent cohorts is still needed, testing for CSC markers in patients with advanced or late stage HNSCC might be beneficial, especially if many comorbidities exist or disease is irresectable. The findings might guide the development and earlier use of targeted therapies in the future.

Electronic supplementary material

The online version of this article (10.1007/s00066-020-01653-5) contains supplementary material, which is available to authorized users.

High-grade Endometrial Carcinomas: Morphologic and Immunohistochemical Features, Diagnostic Challenges and Recommendations

This review of challenging diagnostic issues concerning high-grade endometrial carcinomas is derived from the authors' review of the literature followed by discussions at the Endometrial Cancer Workshop sponsored by the International Society of Gynecological Pathologists in 2016. Recommendations presented are evidence-based, insofar as this is possible, given that the levels of evidence are weak or moderate due to small sample sizes and nonuniform diagnostic criteria used in many studies. High-grade endometrioid carcinomas include FIGO grade 3 endometrioid carcinomas, serous carcinomas, clear cell carcinomas, undifferentiated carcinomas, and carcinosarcomas. FIGO grade 3 endometrioid carcinoma is diagnosed when an endometrioid carcinoma exhibits >50% solid architecture (excluding squamous areas), or when an architecturally FIGO grade 2 endometrioid carcinoma exhibits marked cytologic atypia, provided that a glandular variant of serous carcinoma has been excluded. The most useful immunohistochemical studies to make the distinction between these 2 histotypes are p53, p16, DNA mismatch repair proteins, PTEN, and ARID1A. Endometrial clear cell carcinomas must display prototypical architectural and cytologic features for diagnosis. Immunohistochemical stains, including, Napsin A and p504s can be used as ancillary diagnostic tools; p53 expression is aberrant in a minority of clear cell carcinomas. Of note, clear cells are found in all types of high-grade endometrial carcinomas, leading to a tendency to overdiagnose clear cell carcinoma. Undifferentiated carcinoma (which when associated with a component of low-grade endometrioid carcinoma is termed "dedifferentiated carcinoma") is composed of sheets of monotonous, typically dyscohesive cells, which can have a rhabdoid appearance; they often exhibit limited expression of cytokeratins and epithelial membrane antigen, are usually negative for PAX8 and hormone receptors, lack membranous e-cadherin and commonly demonstrate loss of expression of DNA mismatch repair proteins and SWI-SNF chromatin remodeling proteins. Carcinosarcomas must show unequivocal morphologic evidence of malignant epithelial and mesenchymal differentiation.

Clear Cell Carcinoma of the Endometrium: Evaluation of Prognostic Parameters in a Multi-institutional Cohort of 165 Cases

OBJECTIVES

Clear cell carcinoma (CCC) comprises a rare yet an aggressive subtype, accounting for less than 5% of all uterine carcinomas. Several clinicopathologic features have been predictive of poor prognosis; however, data remain controversial. The aim of this study was to evaluate the clinicopathologic features of a multi-institutional cohort of endometrial CCC in order to identify which, if any, have prognostic significance.

METHODS

Retrospective review of endometrial CCC diagnosed between 1995 and 2012 at 3 institutions was conducted to evaluate clinicopathologic parameters: age, race, tumor size, stage, myometrial invasion (MI), lymphovascular invasion, lymph node and adnexal involvement, adjuvant therapy, and outcomes. Data were analyzed using Fisher exact, Cox regression, and Kaplan-Meier analyses.

RESULTS

Patients' ages ranged from 36 to 90 years (median, 67 years). The median tumor size was 3.6 cm. Inner-half MI was present in 44%, lymphovascular invasion in 34%, adnexal involvement in 16%, and lymph node metastasis in 30% of cases. Fifty-eight percent of the patients presented with early-stage disease. The 5-year overall survival (OS) was 58%. Shorter disease-free interval (DFI) was significantly associated with older age at diagnosis (>70 years), advanced-stage disease, adnexal involvement, and deep MI (P = 0.005, P = 0.001, P = 0.001, and P = 0.003, respectively). Patients who received adjuvant chemotherapy had a significantly worse DFI and 5-year OS (P = 0.001 and P = 0.001, respectively). A significantly shorter 5-year OS was noted with advanced stage (III-IV) and presence of adnexal involvement (P = 0.001 and P = 0.021, respectively). On Cox regression analysis, advanced-stage disease, older age, and adnexal involvement were significant independent predictors of worse DFI (P = 0.001, P = 0.005, and P = 0.019, respectively), whereas inner-half MI was a significant independent predictor of longer DFI (P = 0.004). Adjuvant radiotherapy alone was a significant independent predictor of better 5-year OS (P = 0.012).

CONCLUSIONS

In our series of endometrial CCC, older age at diagnosis, advanced stage, deep MI, and adnexal involvement were independent poor prognostic factors. Adjuvant radiotherapy had a significant positive impact on 5-year OS.

Uterine Clear Cell Carcinoma: Does Adjuvant Chemotherapy Improve Outcomes?

OBJECTIVES

Women with uterine clear cell carcinoma (UCCC) are at high risk of relapse. Adjuvant chemotherapy (CT) is often recommended, although its effectiveness remains controversial. Our objective was to evaluate treatment-related outcomes of patients with UCCC, particularly those treated with adjuvant CT.

METHODS

In this retrospective cohort study, patients diagnosed with UCCC at 2 academic cancer centers from 2000 to 2014 were included. Clinical, surgical, and pathological data were collected. Survival estimates were obtained using the Kaplan-Meier method and compared by log rank test. Multivariable analysis was used to determine the effect of CT and radiation therapy (RT) on overall survival (OS) and progression-free survival (PFS).

RESULTS

We included 146 patients with UCCC, with a median follow-up of 27 months (range, 1-160). Ninety-five (65%) patients presented with stage I to II disease and 51 (35%) with stage III to IV disease. Forty-six percent of patients with clinical stage I were upstaged after surgery: 29% were upstaged to stages III and IV. Thirty-one percent of patients with early-stage disease and 70% with advanced-stage received CT. Among recurrences, the majority had distant relapse in both early-stage (61.5%) and advanced-stage (96.3%) diseases. In both patients with early-stage and advanced-stage diseases, adjuvant CT did not improve OS or PFS. On multivariate analysis, CT was not a significant factor associated with improved PFS (hazard ratio [HR], 1.37; 95% confidence interval [CI], 0.69-2.71; P = 0.37) or OS (HR, 0.58; 95% CI, 0.24-1.38; P = 0.22), whereas RT was associated with improved PFS (HR, 0.51; 95% CI, 0.29-0.90; P = 0.02) and OS (HR, 0.19; 95% CI, 0.09-0.42; P < 0.001).

CONCLUSIONS

The high rate of upstaging after surgery highlights the importance of lymph node assessment. The high rate of distant recurrence questions the effectiveness of current CT regimens and warrants the development of novel systemic approaches. The role of adjuvant RT deserves further study.

Impact of Chemotherapy and Radiotherapy on Management of Early Stage Clear Cell and Papillary Serous Carcinoma of the Uterus

Objective

The aim of the study was to assess interaction of lymph node dissection (LND), adjuvant chemotherapy (CT), and radiotherapy (RT) in stage I uterine papillary serous carcinoma (UPSC) and uterine clear cell carcinoma (UCC).

Methods/Materials

The National Cancer Data Base was queried for women diagnosed with International Federation of Gynecology and Obstetrics stage I UPSC and UCC from 1998 to 2012. Overall survival (OS) was estimated for combinations of RT and CT by the Kaplan-Meier method stratified by histology and LND. Multivariate Cox proportional hazard models were generated.

Results

Uterine papillary serous carcinoma: 5432 women with UPSC were identified. Uterine papillary serous carcinoma had the highest 5-year OS with CT + RT with (83%) or without LND (76%). On multivariate analyses, CT [hazard ratio (HR), 0.77; P = 0.01] and vaginal cuff brachytherapy (HR, 0.68; P = 0.003) with LND were independently associated with OS. Without LND, vaginal cuff brachytherapy (HR, 0.53; P = 0.03), but not CT (HR, 1.21; P = 0.92), was associated with OS. Uterine clear cell carcinoma: 2516 women with UCC were identified. Uterine clear cell carcinoma with and without LND had comparable 5-year OS for all combinations of CT and RT on univariate and multivariate analyses.

Conclusions

In stage I papillary serous uterine cancer, brachytherapy and CT were associated with increased survival; however, the benefit of chemotherapy was limited to those with surgical staging. In contrast, no adjuvant therapy was associated with survival in stage I uterine clear cell carcinoma, and further investigation to identify more effective therapies is warranted.

A comparison of clinico-pathologic characteristics of patients with serous and clear cell carcinoma of the uterus

Objective:

Serous carcinoma and clear cell carcinomas account for 10% and 3% of endometrial cancers but are responsible for 39% and 8% of cancer deaths, respectively. In this study, we aimed to compare serous carcinoma and clear cell carcinoma regarding the surgico-pathologic and clinical characteristics, and survival, and to detect factors that affected recurrence and survival.

Materials and Methods:

We retrospectively analyzed patients with clear cell and serous endometrial cancer who underwent surgery between January 1993 and December 2013 in our clinic. We used Kaplan-Meier estimator to analyze survival.

Results:

The tumor type in 49 patients was clear cell carcinomas and was serous uterine carcinoma in 51 patients. Advanced stage (stage III and IV) disease was present in 42% of the patients in the clear cell group, whereas this rate was 62% in the serous group (p=0.044). Lymph node metastasis was detected in 37% of the patients with clear cell carcinomas and 51% of the patients with serous carcinoma (p=0.17). The adjuvant therapies used did not differ significantly between the groups (p=0.192). The groups had similar recurrence patterns. Five-year progression-free survival and the 5-year overall survival were 60.6% and 85.8%, 45.5% and 67.8% in the patients with clear cell carcinomas and serous tumor, respectively.

Conclusion:

With the exception that more advanced stages were observed in patients with serous carcinoma endometrial cancers at presentation, the surgico-pathologic features, recurrence rates and patterns, and survival rates did not differ significantly between the groups with clear cell carcinoma and serous carcinoma endometrial cancers.

Adjuvant therapy of uterine clear cell carcinoma: a review

PURPOSE

Uterine clear-cell carcinoma (UCCC) is a rare subset of type II endometrial carcinoma with a poor prognosis relative to the most common type of endometrioid carcinoma. Due to its rarity, there has been limited direct evidence of the efficacy of specific adjuvant therapy posthysterectomy in women with UCCC. We present a review of current literature regarding adjuvant therapy of uterine clear cell carcinoma.

METHODS

We searched for English-language publications through Pubmed using a combination of the following key words: endometrial carcinoma, clear cell carcinoma, recurrence, prognosis, adjuvant therapy, radiation treatment and chemotherapy. Due to the rarity of UCCC, studies were not limited by design or number of patients.

RESULTS

There is a paucity of randomized prospective controlled studies focusing on UCCC adjuvant therapy. Findings have largely been derived from retrospective studies of type II endometrial carcinomas or all endometrial cancers as a group. Very few retrospective studies were found to focus on UCCC adjuvant therapy, although certain larger studies did have subset analyses of UCCC patients.

CONCLUSIONS

For early stage disease, locoregional radiotherapy, especially vaginal brachytherapy, has evidence of efficacy. The therapeutic gain of radiotherapy may be further improved with the addition of systemic chemotherapy. Evidence for combined radiation therapy with systemic chemotherapy in women with advanced stage UCCC has remained debatable. UCCC-specific studies are needed to determine the best adjuvant therapy for UCCC without the confounding effects of USC and other endometrial cancers.

Impact of Body Mass Index on Surgical Outcomes and Analysis of Disease Recurrence for Patients With Endometrial Cancer Undergoing Robotic-Assisted Staging

Objective

This study aimed to evaluate the impact of body mass index (BMI) on the short- and long-term outcomes of patients with endometrial cancer who underwent robotic-assisted staging and to analyze disease recurrence and recurrence-free survival (RFS).

Materials and Methods

The charts of all consecutive patients with endometrial cancer who underwent robotic surgery from March 2007 to October 2012 were analyzed. Patients with follow-up less than 12 months after surgery were censored from the RFS analysis.

Results

Mean (SD) age for the 364 patients was 63.6 (10) years, and mean (SD) BMI was 34.8 (10.1) kg/m2. Conversions were in 3 (0.8%) of 364 cases. The mean (SD) operative time was 162.3 (54.6) minutes. Mean (SD) postoperative hospitalization was 1.6 (1.9) days. Histology included 80.5% endometrioid and 19.5% clear cell, serous, and carcinosarcomas. Mean (SD) pelvic and paraaortic lymph node counts were 15.9 (8.2) and 3.6 (4.3), respectively. Metastatic disease was diagnosed in 58 (16%) of 364 patients. The median follow-up was 29.3 months. The recurrence rates were 4.1% for the patients with endometrioid carcinoma and 14.1% for nonendometrioid histologies. Recurrences in patients with BMI less than 30 kg/m2 accounted for 68.2% of all recurrences (15/22 patients). The rest of recurrences (7/22 patients, 31.8%) were in obese patients. Moreover, when analyzed for each histologic subtype, recurrence rates were consistently higher for patients with BMI less than 30 kg/m2 when compared with patients with BMI greater than 30 kg/m2. The 3-year overall survival was 98.2%, and the 3-year RFS was 92%.

Conclusions

Obesity and morbid obesity did not affect adversely the operative outcomes for patients with endometrial cancer who were operated on using the robotic system. The recurrence rates were lower for patients with BMI greater than 30 kg/m2 compared with patients with BMI less than 30 kg/m2 for both endometrioid and nonendometrioid cancers.

Primary peritoneal clear cell carcinoma treated with IMRT and interstitial HDR brachytherapy: a case report

Primary peritoneal clear cell carcinoma (PP‐CCC), which is a rare tumor with poor prognosis, is typically managed with surgery and/or chemotherapy. We present a unique treatment approach for a patient with a pelvic PP‐CCC, consisting of postchemotherapy intensity‐modulated radiation therapy (IMRT) followed by interstitial high‐dose–rate (HDR) brachytherapy. A 54‐year‐old female with an inoperable pelvic‐supravaginal 5.6 cm T3N0M0 PP‐CCC tumor underwent treatment with 6 cycles of carboplatin and taxol chemotherapy. Postchemotherapy PET/CT scan revealed a residual 3.3 cm tumor. The patient underwent CT and MR planning simulation, and was treated with 50 Gy to the primary tumor and 45 Gy to the pelvis including the pelvic lymph nodes, using IMRT to spare bowel. Subsequently, the patient was treated with an interstitial HDR brachytherapy implant, planned using both CT and MR scans. A total dose of 15 Gy in 5 Gy fractions over two days was delivered with Ir‐192 HDR brachytherapy. The total prescribed equivalent 2 Gy dose (EQD2) to the HDR planning target volume (PTV) from both the EBRT and HDR treatments ranged between 63 and 68.8Gy2 due to differential dosing of the primary and pelvic targets. The patient tolerated radiotherapy well, except for mild diarrhea not requiring medication. There was no patient‐reported acute toxicity one month following the radiotherapy course. At four months following adjuvant radiation therapy, the patient had near complete resolution of local tumor on PET/CT without any radiation‐associated toxicity. However, the patient was noted to have metastatic disease outside of the radiation field, specifically lesions in the liver and bone. This case report illustrates the feasibility of the treatment of a pelvic PP‐CCC with IMRT followed by interstitial HDR brachytherapy boost, which resulted in near complete local tumor response without significant morbidity.

PACS number: 87.55.‐x

Morphologic and other clinicopathologic features of endometrial clear cell carcinoma: a comprehensive analysis of 50 rigorously classified cases

Clear cell carcinoma of the endometrium (CCC) is an uncommon histotype whose analyses have generally been hampered by its rarity and issues of interobserver diagnostic variability. In this study, we analyzed the clinicopathologic features of 50 CCCs that were assembled from multiple institutions and which we considered to be morphologically unambiguous after a rigorous review process for diagnostic accuracy. Forty-four (88%) of the 50 CCC cases showed an admixture of the classic architectural patterns (glandular, papillary, solid and cystic in decreasing order of prevalence). Mitotic indices were variable but were generally low: 60% of cases had a mitotic index of 3 or lower. The predominant cell type lining glands and papillae was invariably hobnail and/or cuboidal. Stratification of nuclei (greater than 3 cells) or columnar cells on glands and papillae were uncommon and never diffusely present. 82% of cases showed an admixture of polygonal cells with clear and eosinophilic cytoplasm; only clear cells were present in 4% and only eosinophilic cells were present in 10%. Hobnail cells were common, being identifiable in 86% of cases, and being diffuse in 60%. Only 2 cases had a predominance of nuclear grade 3 cells. Psammoma, hyaline and targetoid bodies were identified in 32%, 52% and 20% of cases respectively. Clear cell endometrial intraepithelial carcinoma was identified in 41.7% of cases with evaluable background endometrium. The 5-year progression free survival (PFS) for the entire cohort was 61%, and was 88%, 75%, 22% and 28.6% for stages I to IV respectively. On univariate analyses, age >65 years, advanced FIGO stage, and the presence of any lymph node metastases were associated with reduced PFS (p=0.02, 0.002, and 0.002 respectively). On multivariate analyses, the only variable associated with reduced PFS was age >65 years. The 5-year overall survival (OS) for the entire cohort was 78%, and was 94%, 87.5%, 66.7%, and 42.8% for stages I to IV respectively. On univariate analyses, the following factors were associated with reduced OS: age >65 years (p=0.04), advanced FIGO stage (p=0.003), distant metastases (p=0.003), myometrial invasion >30% (p=0.01), a mitotic index >4 (p=0.014), and a specific architectural pattern (at least 10% of the tumor composed of solid masses or individual infiltrating tumor cells, p=0.02). On multivariate analyses, only age >65 years and advanced stage were associated with reduced OS (p=0.023 and 0.022 respectively). In summary, endometrial CCC has a wide morphologic spectrum that is detailed and illustrated herein, but also has core cytoarchitectural features that are of high diagnostic utility. Morphologically unambiguous CCC apparently have patient outcomes that are more favorable than has previously been reported, indicating that ambiguous tumors should be classified separately. The existence of morphologically ambiguous clear-cell rich carcinomas that do not fit the conventional histotypic groupings, is a likely reflection of the biologic complexity of endometrial carcinomas in general; these cases should be reported descriptively, and studied separately from conventional CCC.

The diagnosis of endometrial carcinomas with clear cells by gynecologic pathologists: an assessment of interobserver variability and associated morphologic features

The purposes of this study are to assess the level of interobserver variability in the diagnosis of endometrial carcinomas with clear cells by gynecologic pathologists based purely on their morphologic features and to comparatively describe the cases of putative clear cell carcinoma (CCC) with and without significant interobserver variability. A total of 35 endometrial carcinomas (1 slide per case) were reviewed by 11 gynecologic pathologists (median experience: 10 y) from 11 North American institutions. The cases were selected from the files of 3 institutions on the basis of the presence of at least focal clear cells and had previously been classified as a variety of histotypes at these institutions. Diagnoses were rendered in a blinded manner and without predetermined diagnostic criteria or categories. The κ values between any pair of observers ranged from 0.18 to 0.69 (combined 0.46), which was indicative of a "moderate" level of interobserver agreement for the group. Subgroups of "confirmed CCC" [cases diagnosed as such by at least 8 (73%) of the 11 observers, n=14] and "possible CCC" (cases diagnosed as CCC by ≥1 but <8 observers, n=13) were compared with regard to a variety of semiquantified morphologic features. By combining selected morphologic features that displayed statistically significant differences between the 2 groups on univariate analyses, the following approximate morphologic profile emerged for the confirmed CCC group: papillae with hyalinized cores in ≥33% of the lesion, clear cells in ≥33% of the lesion, hyperchromasia in ≥33% of the lesion, the absence of nuclear pseudostratification in >3 cells on the papillae, the absence of nuclear pseudostratification in glands in ≥33% of the lesion, the absence of diffuse grade 3 nuclei, the absence of long and slender papillae in ≥33% of the lesion, and glands and papillae lined by cuboidal to flat, noncolumnar cells. In a backward stepwise logistic regression analysis, features from the profile that predicted the confirmed CCC group included: (1) absence or minimality of diffuse sheets of grade 3 nuclei [P=0.025; 95% confidence interval (CI), 0.0266-0.363]; (2) absence or minimality of nuclear stratification in glands and papillae (P=0.040; 95% CI, -0.228 to -0.0054); and (3) glands and papillae lined by cuboidal to flat, noncolumnar cells (P=0.008; 95% CI, 0.0911-0.566). The 2 groups displayed significant overlap regarding a wide variety of features, and no single case displayed a full complement of potentially diagnostic features. Morphologic patterns associated with cases with very high levels of interobserver variability (defined as cases with ≥4 different diagnoses rendered for them, n=9) included the near-exclusive or exclusively solid pattern of clear cells (3/9) and glandular/papillary proliferations whose only CCC-like feature was the presence of clear cells (2/9). In conclusion, the diagnosis of endometrial carcinomas with clear cells by gynecologic pathologists is associated with a moderate level of interobserver variability. However, there is a morphologic profile that characterizes cases that gynecologic pathologists more uniformly classify as CCC, and the presence of these features is supportive of a CCC diagnosis in an endometrial carcinoma with clear cells. Cases that display broad and significant qualitative deviations from the aforementioned profile should prompt the consideration of a diagnosis other than CCC.