ECP 2023 Abstracts

S57 Virchows Archiv (2023) 483 (Suppl 1):S1–S391 13 Statistical analysis was performed in correlation with clinicopathological parameters, protein and mRNA expression. Results: 55% of TNBCs expressed AR mRNA levels. Low AR mRNA expression was associated with younger age (p=0.017), high histo- logical grade (p<0.001) and poor overall-survival rates (p=0.032) and adjusted with age, tumour size histological grade (p=0.023). Conclusion: Low AR mRNA expression is associated with poorer survival outcome AR mRNA correlated hub-gene panel and its regulatory role in immune cell infiltrations (CCNB2, H2AFZ) and drug resistance (AURKB) provide novel insights into the immune microenviron- ment role in AR+ TNBCs. AR inhibitors increase recruitment of cytotoxic T cells that may enhance sensitivity and susceptibility to immunotherapy. PS-01-003 Ki67 quantitation in breast cancer: a comparative analysis of four counting methods C. Albarracin*, Y. Wu, M. Mersereau, H. Chen *University of Texas, MD Anderson Cancer Center, USA Background & objectives: There is increasing use of Ki67 as a prognostic and predictive marker in breast cancer. Quantitation of immunostains for Ki67 is limited by lack of standard scoring meth- ods. Our goal is to compare four different methods of evaluating Ki67 staining. Methods: 100 cases selected from database of ER+/HER2- inva- sive breast carcinomas. Immunohistochemical stains using MIB-1/ Ki67 antibody were evaluated using four methods. Visual total count microscopically estimated Ki67 in the entire tumour. It served as “gold standard” and compared to Digital total count, Hotspot count and the International Ki67 Working Group Unweighted (IKWG-U) methods. Time utilized for analysis was noted. Results: Visual count was used to classify the 100 cases into Low Ki67 (<17%), Moderate Ki67 (17-35%), and High Ki67 (>35%). Digital count quantified Ki67 in the entire tumour by digital analysis. IKWG-U quantified four areas of different staining densities. In comparison to Visual, Digital and IKWG-U each altered Ki67 categories in 3 of 100 cases. Hotspot quantified areas with highest Ki67 labelling resulting in altered Ki67 categories in 16 of 100 cases. Comparison to Visual count yielded linear regression R2 values of 0.9756 for Digital, 0.9776 for IKWG-U, and 0.8678 for Hotspot. Average time <2 mins for Visual, 28 mins for Digital, 10 mins for IKWG-U, 6 mins for Hotspot. Conclusion: Our study successfully demonstrated that Visual count, Digital count and IKWG-U are reliable and reproducible methods for Ki67 evaluation. While these methods yielded comparable results, Vis- ual count required the least amount of time and can be easily utilized in a clinical setting. In contrast, Hotspot had a lower correlation with Visual count, and its use in clinical practice may be limited. In summary, these results validate the use of Visual count as a viable and effective method to quantify Ki67. PS-01-004 Concordance of Nottingham histologic and neuroendocrine grading schemes in mammary neuroendocrine neoplasms C. Albarracin*, J. Wen, K. Sweeney, Q. Ding, Y. Wu *University of Texas, MD Anderson Cancer Center, USA Background & objectives: IARC/WHO expert panel has proposed a uni- formdiagnostic scheme for neuroendocrine neoplasm (NEN) of all the organs including breast. The objective of the current study is to compare the Not- tingham histologic grading and NEN grading scheme in mammary NEN. Methods: Eighty NENs (15 NEC and 65 NET) were identified from surgical pathology file at University of Texas MD Anderson Cancer Center between 2008 and 2020. The histologic grade of those cases was compared using Nottingham histologic grading scheme (glandu- lar formation + nuclear pleomorphism + mitosis) and NEN grading scheme (mitosis and Ki67 proliferation rate). Kendall’s co-efficiency concordance was calculated. Results: There was overall good agreement between Nottingham his- tologic grading and NEN grading scheme (Kendall’s co-efficiency of 0.844) for all the cases. There was complete concordance of the two grading schemes in neuroendocrine carcinoma (NEC) (Kendall’s co- efficiency of 1). The concordance co-efficiency for neuroendocrine tumour (NET) is 0.72. Conclusion: NEN is a unique pathologic and clinical entity of the breast. Although WHO recommends using Nottingham histologic grad- ing scheme for this type of tumour in breast, Nottingham histologic grading scheme has a high concordance with NEN grading scheme. PS-01-005 TRPS1 expression in cytokeratin 5 expressing triple negative breast cancers, its value as a marker of breast origin S. Almási*, L. Kuthi, A. Sejben, A. Voros, Á. Nagy, T. Zombori, G. Cserni *University of Szeged, Hungary Background & objectives: Triple negative breast cancer (TNBC) lack the expression of ER, PR, and HER2. The majority of them do not express breast markers either, such as GCDFP-15, GATA3, MGB and SOX10, therefore identification could present as a major challenge. Methods: Our aim was to evaluate trichorhinophalangeal syndrome type 1 (TRPS1) protein as a breast marker in a series of cytokeratin- 5-expressing TNBC, mostly corresponding to basal-like TNBCs, pre- viously characterized for the expression of other breast markers. One hundred seventeen TNBCs in tissue microarrays were immunostained for TRPS1. The cut-off for positivity was ≥ 10%. The reproducibility of this classification was also assessed. Results: TRPS1 positivity was detected in 92/117 (79%) cases, and this exceeded the expression of previously tested markers like SOX10: 82(70%), GATA3: 11(9%), MGB: 10(9%) and GCDFP-15: 7(6%). Of the 25 TRPS1-negative cases, 11 were positive with SOX10, whereas 5 to 6 dual negatives displayed positivity for the other makers. The evaluation showed substantial agreement. Conclusion: Based on our results, of the five markers compared, TRPS1 seems the most sensitive marker for the mammary origin of CK5-expressing TNBCs. Cases that are negative are most often labelled with SOX10, and the remainder may still demonstrate posi- tivity for any of the three other markers. TRPS1 has a place in breast marker panels. This research was funded by the University of Szeged, Faculty of Medicine Research Fund-Hetényi Géza Grant (Grant No. 5S 340 A202) PS-01-006 NGS mutational status on first diagnostic tissue and liquid biopsy in breast cancer C.M. Ardeleanu*, M. Olinca, B. Galateanu, H. Muresan, A. Tecuceanu Vulpe, I. Gune, G. Manole, M. Bugeanu, A. Hudita *Onco Team Diagnostic, Romania Background & objectives: Breast cancer mutations modify the tumour aggressiveness, drug resistance, residual disease. Aim: to assess by NGS the mutational status of G2-G3 breast tumours in evolution, on tissue and liquid biopsies at the first diagnostic and after mastectomy, on residual tumour. Methods: From primary breast tumours (24), core biopsies were formalin fixed, paraffin embedded, Haematoxilin-Eosine stained; Ventana-Benchmark-Ultra (ER-Ventana-6F11, PGR-Ventana-16, cerbB2-Ventana-4B5), Bond-III Leica (Ki67-Leica-MM1), assured immunohistochemistry; results: ER/PGR/Ki67 percentage; cerbB2 ASCO/CAP/2018score.