Microsatellite instability evaluation: which test to use for endometrial cancer?

Performance of the Idylla microsatellite instability test in endometrial cancer

CONTEXT

DNA mismatch repair (MMR) deficiency (dMMR) testing is now recommended in endometrial cancer. Defect identification in the molecules participating in this pathway, or the presence of microsatellite instability, are commonly employed for this purpose. Novel methods are continuously evolving to report dMMR/microsatellite instability and to easily perform routine diagnoses.

OBJECTIVE

The main aim of this study was to compare the concordance of the Idylla microsatellite instability test for the identification of dMMR endometrial cancer samples defined by immunohistochemistry and MMR genomic status.

DESIGN

We applied the Idylla MSI test to 126 early-stage endometrial cancer cases with MMR testing by immunohistochemistry and genomic characterization (methylation in MLH1 and sequence alterations in MLH1, PMS2, MSH2 and MSH6). Individual markers and overall specific performance indicators were explored.

RESULTS

The Idylla platform achieved a higher global concordance rate with MMR genomic status than with immunohistochemistry (75 % and 66 %, respectively). Sensitivity and specificity are also higher (75 % vs 66 % and 96 % vs 90 %, respectively). Clustering analysis split the patients into 2 well-differentiated clusters, the pMMR and the dMMR group, represented by MLH1/PMS2 loss and the MLH1 methylated promoter. Overall, immunohistochemistry and MMR genomic status identified more dMMR cases than did the Idylla test, although correlations were improved with a modified Idylla test cut-off.

CONCLUSIONS

Performance of the Idylla test was better correlated with MMR genomic status than MMR immunohistochemistry status, which improved with a modified test cut-off. Further studies are needed to confirm the cut-off accuracy.

Predictive Value of Magnetic Resonance Imaging in Risk Stratification and Molecular Classification of Endometrial Cancer

This study evaluated the magnetic resonance imaging (MRI) findings of endometrial cancer (EC) patients and identified differences based on risk group and molecular classification. The study involved a total of 175 EC patients. The MRI data were retrospectively reviewed and compared based on the risk of recurrence. Additionally, the associations between imaging phenotypes and genomic signatures were assessed. The low-risk and non-low-risk groups (intermediate, high-intermediate, high, metastatic) showed significant differences in tumor diameter (p < 0.001), signal intensity and heterogeneity on diffusion-weighted imaging (DWI) (p = 0.003), deep myometrial invasion (involvement of more than 50% of the myometrium), cervical invasion (p < 0.001), extrauterine extension (p = 0.002), and lymphadenopathy (p = 0.003). Greater diffusion restriction and more heterogeneity on DWI were exhibited in the non-low-risk group than in the low-risk group. Deep myometrial invasion, cervical invasion, extrauterine extension, lymphadenopathy, recurrence, and stage discrepancy were more common in the non-low-risk group (p < 0.001). A significant difference in microsatellite stability status was observed in the heterogeneity of the contrast-enhanced T1-weighted images (p = 0.027). However, no significant differences were found in MRI parameters related to TP53 mutation. MRI features can be valuable predictors for differentiating risk groups in patients with EC. However, further investigations are needed to explore the imaging markers based on molecular classification.

Advancing Tailored Treatments: A Predictive Nomogram, Based on Ultrasound and Laboratory Data, for Assessing Nodal Involvement in Endometrial Cancer Patients

Assessing lymph node metastasis is crucial in determining the optimal therapeutic approach for endometrial cancer (EC). Considering the impact of lymphadenectomy, there is an urgent need for a cost-effective and easily applicable method to evaluate the risk of lymph node metastasis in cases of sentinel lymph node (SLN) biopsy failure. This retrospective monocentric study enrolled EC patients, who underwent surgical staging with nodal assessment. Data concerning demographic, clinicopathological, ultrasound, and surgical characteristics were collected from medical records. Ultrasound examinations were conducted in accordance with the IETA statement. We identified 425 patients, and, after applying exclusion criteria, the analysis included 313 women. Parameters incorporated into the nomogram were selected via univariate and multivariable analyses, including platelet count, myometrial infiltration, minimal tumor-free margin, and CA 125. The nomogram exhibited good accuracy in predicting lymph node involvement, with an AUC of 0.88. Using a cutoff of 10% likelihood of nodal involvement, the nomogram displayed a low false-negative rate of 0.04 (95% CI 0.00-0.19) in the training set. The adaptability of this straightforward model renders it suitable for implementation across diverse clinical settings, aiding gynecological oncologists in preoperative patient evaluations and facilitating the design of personalized treatments. However, external validation is mandatory for confirming diagnostic accuracy.

Clinical characteristics and prognostic characterization of endometrial carcinoma: a comparative analysis of molecular typing protocols

BACKGROUND

Endometrial carcinoma (EC) is one of the most common gynecological malignancies in China and globally, accounting for the fourth-prevalent cancer in women. Although numerous studies have confirmed prognostic value of The Cancer Genome Atlas (TCGA) molecular subgroups, it is unclear how they are combined with histological features. The main objective of this study was to compare ProMisE and TCGA classification for the rapid and accurate prediction of prognosis within EC patients, together with the provision of a revised strategy for individualized diagnosis and treatment of patients.

METHODS

Within this study, 70 patients with EC from Beijing Tsinghua Changgeng Hospital (affiliated to Tsinghua University) were retrospectively examined between July 2015 and December 2021. Samples were processed for determination of clinical markers, together with ProMisE and TCGA classification.

RESULTS

Comparative analysis across four TCGA types (POLE, Low-CN, High-CN, and MSI-H) and age, was statistically significant (χ²= 7.000, p = 0.029). There was no significant difference observed among the four TCGA types and FIGO stage, vascular invasion and depth of invasion, or lymph node metastasis and tumor area. There was no significant association between the expression of Vimentin, Ki-67, PTEN, MSH2, PAX-8, β-catenin, CD10, ER, PR, P16, MLH1, and PMS2 with the four TCGA types. In addition, p63 expression (χ²= 11.09, p = 0.029) and p53 expression (χ²= 11.585, p = 0.005) were statistically significant. Numerous models demonstrated that patients with POLE mutations and low-CN had higher progression free survival (PFS) and overall survival (OS), whereas those with high-CN had lowest values. The log-rank test revealed that the survival rate of PR-positive and ER-positive patients was significantly higher (p < 0.001).

CONCLUSION

Overall, these results can be of additional benefit for clinical applications, in comparison to the ProMisE classification method. In addition, PR, ER, vascular infiltration, hyperlipidemia and atherosclerosis were found to be the key factors affecting EC prognosis.

Discordance of microsatellite instability and mismatch repair immunochemistry occurs depending on the cancer type

Microsatellite instability (MSI) and deficiency of mismatch repair (dMMR) are key markers for predicting the response of immune checkpoint inhibitors (ICIs) and screening for Lynch syndrome (LS). This study examined the incidences of and factors associated with the concordance of MSI and MMR in human cancers. A total of 518 formalin-fixed cancer tissues were analyzed for MSI and MMR immunohistochemistry (IHC). MSI was analyzed by a PCR-based method using Promega markers. Concordance with MMR expression and factors associated with concordance were analyzed. In 2 colorectal cancer samples, MMR IHC failed due to inadequate staining conditions. In the remaining 516 cancers, a high level of MSI (MSI-H) was identified in 113 cases, and dMMR was identified in 112. The concordance of MSI and MMR IHC was 98.3%. Only 9 cases (4 pancreatobiliary, 3 colorectal, and 2 endometrial cancers) were discordant. Of the 113 MSI-H cases, 4 (3.5%) were proficient MMR (pMMR); of the 403 microsatellite stability (MSS) cases, 5 (1.2%) were dMMR. The independent factors associated with MSI-H/dMMR included meeting Amsterdam II criteria, assay purpose, and sampling method. Multivariate analysis revealed that cancer type (gastrointestinal cancers or others) was associated with concordance of MSI and MMR IHC. Three LS cases with pancreatic or endometrial cancer demonstrated MSS and dMMR, and one biliary cancer showed MSI-H and pMMR. Discordance between MSI and MMR IHC occasionally occurs in pancreaticobiliary and endometrial cancers. When suspected, both MSI and MMR IHC should be done to judge the ICI indication and screen for LS.

Critical aspects of MSI testing in endometrial cancer: a comparison study

The identification of mismatch repair deficient (dMMR) and microsatellite unstable (MSI) endometrial cancers (ECs) is important in screening, diagnosis and therapeutic stratification of patients. We compared the diagnostic performance of four MSI molecular tests based on fragment length assay in capillary electrophoresis (OncoMate™ MSI assay, Promega) and in microcapillary electrophoresis (TapeStation 4200, Agilent); with high-resolution melting (HRM) analysis approaches (Idylla™ MSI Test, Biocartis; EasyPGX® ready MSI, Diatech Pharmacogenetics) on a series of 56 ECs, which was well characterized for MMR status with immunohistochemical approach (IHC, non-molecular reference test). The concordance of fluorescence capillary electrophoresis with IHC (AUC 0.98) was higher respect to the other molecular methodologies. Otherwise, HRM approaches and microcapillary electrophoresis platform failed to detect MSI-ECs showing minimal microsatellite shifts. In conclusion, whereas in colorectal site several technologies are eligible for MSI test, in ECs MSI test should be based on fluorescent capillary electrophoresis as it identifies a higher proportion of cases that could be misdiagnosed with other strategies.

Idylla MSI test combined with immunohistochemistry is a valuable and cost effective strategy to search for microsatellite instable tumors of noncolorectal origin

Recent diagnostic and therapeutic progresses have increased the need of searching for microsatellite instability (MSI) in cancer samples beyond colorectal cancer (CRC) ones. The availability of the fully-automated Idylla MSI test (Biocartis), implementable easily in pathology laboratories, offers the opportunity to reconsider MSI diagnostic strategies towards rapid and in-house diagnosis. In this study, we evaluate the performances and cost-effectiveness of an in-house Idylla MSI testing in comparison with an externalized testing of about 54 non-CRC tumor samples. The Idylla MSI test concluded in valid analyses in 53/54 (98.1%) tumor samples with MSI statuses concordant with external molecular and immunohistochemical testing in 50/53 (94.3%) samples. Wrong Idylla MSI test results were obtained in 3/53 (5.7%) samples. Manual checking of microsatellite analyses results and confrontation between the results of Idylla and immunohistochemical analyses have permitted detection and correction of the discrepancies. The implementation of an in-house Idylla MSI testing for non-CRC tumors, necessarily combined with immunohistochemistry searching for MSI tumors, appeared not only valuable in terms of performances, but also in terms of cost-effectiveness without increasing the analyses-related costs but decreasing dramatically their turnaround times to one single working day.