Despite Diagnostic Morphology, Many Mixed Endometrial Carcinomas Show Unexpected Immunohistochemical Staining Patterns:

Pure and mixed clear cell carcinoma of the endometrium: A molecular and immunohistochemical analysis study

BACKGROUND

Uterine clear cell carcinoma (CCC) consists of either pure clear cell histology but can also display other histological components (mixed uterine CCCs). In this study, the molecular and immunohistochemical background of pure and mixed uterine CCC was compared. Secondly, it was evaluated whether histological classification and molecular background affected clinical outcome.

METHODS

A retrospective multicenter study was performed comparing pure uterine CCCs (n = 22) and mixed uterine CCCs (n = 21). Targeted next-generation sequencing using a 12-gene targeted panel classified cases as polymerase-ε (POLE) mutated, microsatellite instable (MSI), TP53 wildtype or TP53 mutated. Immunohistochemistry was performed for estrogen receptor, progesterone receptor, L1 cell adhesion molecule, MSH6, and PMS2.

RESULTS

The following molecular subgroups were identified for pure and mixed uterine CCCs, respectively: POLE mutated 0% (0/18) and 6% (1/18); MSI in 6% (1/18) and 50% (9/18); TP53 wildtype in 56% (10/18) and 22% (4/18); TP53 mutated in 39% (7/18) and 22% (4/18) (p = 0.013). Patients with mixed CCCs had improved outcome compared to patients with pure CCCs. Frequent TP53 mutations were found in pure CCCs and frequent MSI in mixed CCCs, associated with clinical outcome.

CONCLUSION

Pure and mixed uterine CCCs are two entities with different clinical outcomes, which could be explained by different molecular backgrounds. These results underline the relevance of both morphological and molecular evaluation, and may assist in tailoring treatment.

Data Set for the Reporting of Endometrial Cancer: Recommendations From the International Collaboration on Cancer Reporting (ICCR)

Endometrial cancer is one of the most common cancers among women. The International Collaboration on Cancer Reporting (ICCR) developed a standardized endometrial cancer data set in 2011, which provided detailed recommendations for the reporting of resection specimens of these neoplasms. A new data set has been developed, which incorporates the updated 2020 World Health Organization Classification of Female Genital Tumors, the Cancer Genome Atlas (TCGA) molecular classification of endometrial cancers, and other major advances in endometrial cancer reporting, all of which necessitated a major revision of the data set. This updated data set has been produced by a panel of expert pathologists and an expert clinician and has been subject to international open consultation. The data set includes core elements which are unanimously agreed upon as essential for cancer diagnosis, clinical management, staging, or prognosis and noncore elements which are clinically important, but not essential. Explanatory notes are provided for each element. Adoption of this updated data set will result in improvements in endometrial cancer patient care.

A "Null" Pattern of p16 Immunostaining in Endometrial Serous Carcinoma: An Under-recognized and Important Aberrant Staining Pattern

The ability to distinguish endometrial serous carcinoma (SC) from high-grade endometrioid adenocarcinoma is of great importance given their differences in prognosis and management. In practice, this distinction typically relies upon the use of a focused immunohistochemical panel including p53, p16, and mismatch repair proteins. The expression of p16 is characteristically strong and diffuse in SCs, and weak and/or patchy in many high-grade endometrioid adenocarcinomas. Here, we report a subset of SCs that are entirely negative for p16 immunostaining, a pattern we refer to as "p16 null." This pattern was identified in 2 of 63 cases of SC diagnosed at our institution-1 with histologically classic features and 1 with ambiguous high-grade histologic features. These tumors otherwise showed a SC signature by immunohistochemical and demonstrated an SC pattern of genetic mutations. No mutation in the gene for p16, cyclin-dependent kinase inhibitor 2A (CDKN2A), was identified in either case. However, molecular correlates for the absent p16 expression were present, including homozygous deletion of CDKN2A in one case and hemizygous deletion of CDKN2A with promotor hypermethylation of the remaining allele in the other case. To our knowledge, this constitutes the first report conclusively demonstrating the existence of a small subset of SCs that are completely negative by p16 immunohistochemistry, and the molecular lesions responsible for this pattern. In the context of an otherwise clinically and histologically classic example of SC, we endorse this "null" p16 staining pattern as an alternative aberrant staining pattern that should not deter one from committing to this diagnosis.

DNA mismatch repair deficiency and p53 abnormality are age-related events in mixed endometrial carcinoma with a clear cell component

Mixed endometrial carcinoma (MEC) is defined as a tumor composed of two or more spatially distinct subtypes, at least one of which is serous or clear cell carcinoma. In this study, the clinicopathological features of 15 MEC cases containing a clear cell component (MEC-C) were investigated. The ages of patients ranged from 32 to 83 years (median, 61 years). The combinations of carcinoma components observed were endometrioid and clear cell in ten patients; endometrioid, clear cell and serous in three; and clear cell and serous in two. Immunohistochemically, nine had DNA mismatch repair (MMR) protein deficiency (MMR-d), nine had loss of ARID1A and three cases had aberrant p53 expression. MMR-d and loss of ARID1A showed a strong correlation. Only one case showed both MMR-d and aberrant p53 expression. The patients with MMR-d were younger than those without MMR-d (median; 58 years vs. 71 years). Loss of ARID1A also showed significant predilection for younger women than ARID1A intact cases. In conclusion, MMR-d was observed in 60 % of MEC-C, showed predilection for young women, and was associated with ARID1A loss. In contrast, non- MMR-d MEC-C occurred in elder women and some tumors may associate with TP53 mutation. These findings suggest that MEC-C develop via two different molecular mechanisms and they are age-related events.

How do different histologic components of mixed endometrial carcinomas affect prognosis? Does it really matter?

The aim of this study is to evaluate and compare outcomes of patients with mixed and pure endometrial carcinomas (MEC). We reviewed data of patients with MEC, endometroid (EC), serous (SC), and clear cell (CC) carcinomas between 2002 and 2015. Overall survival (OS) and disease-free (DF) survival rates were evaluated, according to the percentage of histologic components. Clinicopathological variables and treatment strategies were assessed. Furthermore, χ ² tests were used to compare proportions and Kaplan-Meier curves to compare recurrence and survival. Sample consisted of 302 cases with mean age 66.3 years. Early-stage disease was recorded in EC compared with CC and SC. Adnexal involvement was more frequent in MEC compared with EC (p=0.043). Extra uterine metastasis was more frequent in the SC compared to the EC group, while lymphovascular space involvement was more frequent in the MEC and CC compared to the SC (p=0.001). EC had less omentum involvement compared to CC (p=0.035) and SC (p<0.001). Furthermore, cervical involvement was more frequent in CC compared to EC (p=0.011). Recurrence (p=0.265) and OS (p=0.533) were found to be similar in MEC compared with CC, SC, and EC. Moreover, recurrence and OS were similar between EC-CC and EC-SC. There were no differences in recurrence and survival in MEC with a type II component larger than 10% or 20% (p>0.05).

Researches on the Correlation Between Estrogen and Progesterone Receptors Expression and Disease-Free Survival of Endometrial Cancer

Objective

In this study, 345 patients with endometrial carcinoma (EC) were selected to investigate the correlation between ER/PR status and the EC disease-free survival (DFS) rate.

Methods

The intensity and proportion of tumor cell expression of estrogen receptors and progesterone receptors (ER/PR) status of 345 postoperative tumor specimens in ECs were independently assessed semi-quantitatively by two pathologists using immunohistochemistry, the summed score ranged from 0 to 8 points was worked out by adding proportion score and intensity score based on the breast cancer hormone receptor immunohistochemical Allred scoring system. The association between DFS in ECs and ER/PR expression (intensity, proportion and summed score) was assessed using Cox regression analysis. Gene expression data were obtained from The Cancer Genome Atlas research network (TCGA).

Results

According to inclusion criteria, 201 type I and 144 type II EC patients were enrolled in this study. In the univariate analysis of type I endometrial carcinoma, the intensity, proportion and summed score of ER/PR status were significantly correlated with DFS. After adjusting for factors known to significantly impact survival, the influence of ER/PR status on DFS is generally decreased but the correlation is still significant. In the univariate analysis of type II endometrial carcinoma, the intensity, proportion and summed score of ER/PR status were significantly correlated with DFS. After adjusting for factors known to significantly impact survival, the influence of ER status on DFS is generally decreased, but the correlation is still significant, the effect of PR expression on DFS is not statistically significant.

Conclusion

Higher ER/PR expression status was associated with better DFS in patients with type I endometrial cancer after adjusting for known factors that significantly affect survival. In patients with type II endometrial cancer, patients with positive ER expression were significantly associated with better DFS. However, the effect of PR expression on DFS was not statistically significant.

Molecular Profiles of Mixed Endometrial Carcinoma

Mixed endometrial carcinomas are defined as a combination of 2 or more distinct histologic subtypes, one of which must be a type II tumor comprising at least 5% of the tumor volume. The oncogenesis of these tumors remains unclear, particularly in light of the increasingly appreciated morphologic overlap among subtypes, as well as evolving molecular data. We evaluated 8 cases of mixed endometrial carcinoma, including 4 endometrioid (EC)/serous (SC), 1 SC/clear cell (CC), and 3 EC/CC cases, to study the underlying molecular features and oncogenic mechanisms at play. Each component was analyzed by a targeted next-generation sequencing assay. All tumors shared mutations in both components. In 6 cases, one component showed additional mutations. Two EC/SC cases showed shared mutations and mutations unique to each component. When present, unique mutations were typically seen in the SC component, including variants in POLE and TP53, as well as potentially targetable genes DDR2, MAP2K1, and CCNE1. In EC/SC tumors, ERBB2 abnormalities were seen in 2 cases. EC/CC cases showed FGFR2 activating mutations in the EC component only. No fusion drivers were identified. Our data suggest that the majority of these tumors begin as a single clone and diverge along 2 pathways: (1) tumor progression, with one component showing additional mutations, and (2) tumor divergence, in which tumor components have both shared mutations and mutations unique to each component. In addition, the findings suggest a component of morphologic mimicry in these tumors. Our findings are clinically relevant since targetable mutations may be present in only one component of mixed tumors.

The Prognosis of Stage IA Mixed Endometrial Carcinoma

OBJECTIVES

To explore the survival and definition of stage IA mixed endometrial carcinoma.

METHODS

From June 1, 2010, to June 1, 2017, cases with stage IA endometrial cancer were included in this study. The survival outcomes were compared among patients with endometrioid (group A), nonendometrioid (group B), and mixed subtypes (group C) and among patients with different proportions of nonendometrioid components (<5%, >50%, and others).

RESULTS

In total, 890 cases were included, comprising 808 (90.8%), 33 (3.7%), and 47 (5.3%) cases in groups A, B, and C, respectively. After a median follow-up of 55.9 months, groups B and C had significantly more inferior disease-free survival, overall survival, and cancer-specific overall survival. Patients with a nonendometrioid proportion of more than 50% and serous subtype also had a significantly more inferior prognosis. Adjuvant therapy could improve the prognosis in mixed endometrial carcinomas.

CONCLUSIONS

Patients with endometrial cancer of mixed subtypes had inferior survival outcomes.