ECP 2022 Abstract Book

Virchows Archiv (2022) 481 (Suppl 1):S1–S364 13 (71 POLE -mutated, 156 POLE -wild type), 20 samples (8.8%) fell in the equivocal range (10 POLE -mutant, 10 POLE -wildtype). Sen- sitivity and specificity for the combined QPOLE assays were 93.4% (95%CI 90.1-96.7%) and 100%. QPOLE combined with NGS for equivocal cases yields a final sensitivity of 94.4% (95%CI 91.6- 97.2%), while maintaining a 100% specificity. Conclusion: With this qPCR assay, QPOLE , we have developed a simple, faster, reliable and sensitive alternative for targeted NGS of all pathogenic somatic variants in the exonuclease domain of the POLE -gene. The simplicity of the design enables assessment of POLE -status within 4 hours, and will make universal low-cost POLE -testing available for all EC patients. An interlaboratory vali- dation study to determine the assay’s practical feasibility is ongo- ing; results are available at the time of the conference. OFP-02-004 Molecular characterisation of endometrial carcinoma and prognostic risk group classification M.E. Brizzi*, Á. López-Janeiro, V. Heredia Soto, A. Berjón, L. Yébenes, A. Peláez-García, M. Mendiola, D. Hardisson *Department of Pathology, Hospital Universitario La Paz, Spain Background & objectives: Molecular classification of endome- trial carcinoma (EC) has been recently incorporated into prognostic risk classification of endometrial carcinoma and should be inte- grated into conventional pathologic diagnosis. Methods: We included EC cases diagnosed in our Department between September 2019 and March 2022. Clinicopathological features were retrieved from the electronic medical records of the patients. Molecular classification was performed by the TCGA sur- rogate testing immunohistochemical markers (p53, MLH1, PMS2, MSH2 and MSH6) and somatic mutation analysis of POLE. Prog- nostic risk group stratification was established according to ESGO- ESTRO-ESP 2021 guidelines. Results: We found 92 patients with EC, 80 of which underwent surgery. Most cases were low-grade early stage endometrioid car- cinomas (85%). According to the molecular classification, 25% EC showed mismatch repair deficiency (MMRd), 15% were p53abn (all high-grade, mostly at advanced stages), 6.5% showed a pathogenic POLE mutation, and 50% were of no specific molecular profile (NSMP). Three cases displayed more than one alteration (“multiple classifiers”). According to clinicopathological features, 38 cases were low-risk, 12 intermediate, 9 intermediate-high, 18 high-risk, and 2 advanced metastatic. After integrating molecular classifica- tion, a risk-group shift occurred in 3 patients (one p53abn from low to intermediate risk, and 2 POLEmut from high-intermediate to low-risk). Conclusion: There is good correlation between molecular classi- fication and histological subtypes: all p53abn tumours were high- grade carcinomas (43% presented at advanced stage), whereas POLEmut cases were mostly low-grade endometrioid carcinomas. Inclusion of this surrogate marker approach to the molecular-based classification is prognostically informative in low-, intermediate-, and high-risk endometrial carcinoma. Changes in prognostic risk group classification occur mainly in p53abn and POLEmut cases. According to current guidelines, molecular classification is encour- aged in all endometrial carcinomas, especially high-grade tumours. OFP-02-005 Comparison of tumour infiltrating lymphocytes between endo- metrial carcinoma primary tumours and matched metastases D. Martins*, E. Sustatxa, M. Pires, L. Azevedo, C. Jerónimo, C. Bartosch *Pathology Department , Centro Hospitalar São João, Porto; Medi- cal Faculty, University of Porto, Portugal Background & objectives: Tumour infiltrating lymphocytes (TILs) in endometrial carcinoma can stimulate anti-tumour immune response and have been shown to impact survival. In some tumour models decreased TILs in metastases was shown, but in metastatic/ recurrent endometrial carcinoma limited data is available. Methods: We studied a cohort of 39 primary endometrial endometrioid carcinomas and matched metastases, diagnosed between 2000 and 2013, at two Portuguese tertiary centers. Patient’s clinical files and histological slides were retrospec- tively reviewed. The number of TILs per square millimeters was automatically determine using QuPath in 6 (primary) and 3 (metastasis) random fields for each case. Results: The number of TILs in metastases had a significant, but weak, correlation with the number of TILs in primary tumours (rs=0.40, p=0.01). Metastases had a median of 238 TILs/mm2 (range:4,1871), with no difference between distant versus regional metastases, nor between lymph-node versus other sites (perito- neum, lung, bone). Primary tumours had a median of 262 TILs/ mm2 (range:0,1013). Twenty metastases showed a decrease in the number of TILS compared to matched primary tumours, and 18 showed an increase. Variations in TILs numbers do not correlate with metastases site, grade or mitotic count. Even though not sta- tistically significant, patients with higher number of TILs in metas- tasis had a better overall survival (HR:0.43, p=0.11). Conclusion: The immune microenvironment in endometrial car- cinoma metastases seems to be variable, either with an increase or decrease in TILs compared to primary tumours. Further studies with larger series are needed to confirm our findings and determine the factors underlying this variation. OFP-02-006 DNA methylation analysis of endometrial carcinomas identifies molecularly and clinically distinct subgroups J. Li 1 , F. Kommoss 1 , A. Lum, D. Chiu, V. Yuan, S. Leung, D.G. Huntsman, J.N. McAlpine, A. von Deimling 2 , B. Tessier-Cloutier* *Memorial Sloan Kettering Cancer Center, USA Background & objectives: DNA methylation analysis is an emerg- ing approach with great potential to further our understanding of oncogenic mechanisms and assisting with tumour classification. In this study we set to characterize a group of endometrial carcinomas using their methylation profile. Methods: We collected a series of molecularly profiled (using ProMisE) and clinically annotated endometrial carcinomas. Methylation analysis was done using the Illumina Infinium EPIC (850k) BeadChip with subsequent unsupervised clustering of the differentially methylated regions. Statistical analyses including two-tailed T-Tests, Chi-Squared tests, and Kaplan Meier sur- vival analysis were done across various clinical and molecular variables. Results: Our cohort (n=50) included 10 POLE mutated ( POL- E mut), 10 MMR-deficient (MMRd), 10 p53 abnormal (p53abn), and 20 with no specific molecular profile (NSMP). The unsuper- vised clustering analysis identified two major methylation groups (A and B), each with two subgroups (A1/2 and B1/2). Clusters A and B differed significantly in terms of molecular subtypes (p<0.001): cluster A only included NSMP and p53abn cases, while cluster B had high representation of MMR-deficient and POLE mut tumours. Deep myometrial invasion (stage IB), lower BMI, and beta-catenin expression were associated with cluster B (p=0.040, 0.009, and 0.037 respectively). Survival analysis S7