ECP 2022 Abstract Book

Virchows Archiv (2022) 481 (Suppl 1):S1–S364 13 suspicious of malignancy (19), dysplasia (12) and normal/other(3). Of the 101 cases with confirmed CRC, 73.7% had ≥6 biopsies and 26.3% had <6 biopsies. Of the 34 cases without a definite diagnosis, 55.9% had ≥6 biopsies. Repeat procedure was required for diagnostic purposes in 10 cases, 4 of which already had ≥6 initial biopsies taken. For molecular testing, estimated tumour content was provided in 57% of confirmed cases. Cases with <6 or ≥6 biopsies had comparable tumour content of 37% and 38% respectively. Conclusion: In the majority of cases, the number of biopsies taken for suspected CRC at our hospital is in line with ESGE recommen- dations. Our findings suggest that the quality of targeted biopsies is also relevant, as a definite diagnosis was achieved in more than quarter of cases with less than 6 initial biopsies. Furthermore, more than half of initial unconfirmed cases met the recommended num- ber of 6. In addition, the number of biopsies taken does not appear to affect tumour content. OFP-01-008 Epithelial-mesenchymal transition and α-SMA expression in the tumour microenvironment: role in tumour stroma composition and association with prognosis in colorectal cancer R. Souza da Silva*, F.F.N. Gomes, J.P. Andrade, L.E.d.M. Barbosa, D.S.G. Silva *Universidade Federal da Paraíba, Brazil Background & objectives: The epithelial-mesenchymal transition is characterized by increased expression of mesenchymal markers and plays an essential role in promoting tumour invasion and metas- tasis. We analysed the association between overall survival and α-SMA expression in colorectal cancer (CRC). Methods: The TSR in colorectal adenocarcinoma was cat- egorized into 2 groups: ≤50%- low stroma and >50%- high stroma. The immunohistochemical expression of α-SMA was observed in cancer cells (CCs) and cancer-associated fibroblasts (CAFs) present in different tumour areas: estima- tive stromal (ES), invasion front and desmoplastic stroma. α-SMa immunostaining >10% was defined as positive. The association between α-SMA expression and overall survival was evaluated. Results: A total of 158 cases were analysed, with 54% of the tumours presenting stroma high. Positive immunostaining of α-SMA was detected, in CCs and CAFs, in 80.3% of cases. Stroma- high tumours showed increased expression of α-SMA. Cancer cells with expression of α-SMA were observed in 59.6% of cases. CAFs expressing α-SMA were found in 87.2% of the cases, higher posi- tivity was observed predominantly in the ES and invasion front areas: 88.9% and 86.7% of cases, respectively. The positive immu- nostaining observed in CCs and CAFs present in the area of stro- mal estimation showed correspondence with death outcome. The high expression of α-SMA, in CAFs present in the invasion front and in the desmoplastic stroma, was associated with lower overall survival. Conclusion: The α-SMA is a mesenchymal biomarker related to the epithelial-mesenchymal transition and is highly expressed in different tumour areas of the CRC, which are associated with a worse prognosis. Cancer cells and CAFs show high expression of α-SMA. The immunoexpression of this biomarker showed cor- respondence with the death outcome. In CRC, high expression of α-SMA in CAFs is associated with shorter overall survival. OFP-01-009 Digital spatial profiling and proteomics identifies differences in biological phenotypes of tumour deposits and lymph node metastases in colorectal cancer N. Brouwer*, L. Webbink, S. van Lent-van Vliet, P. Jansen, R. Geene, I. Nijman, F. Simmer, D. Tauriello, M. Vermeulen, I. Nagtegaal *Department of Pathology, Radboud University Medical Centre, The Netherlands Background & objectives: Both lymph node metastases (LNM) and tumour deposits (TD) are currently included in nodal staging of colorectal cancer (CRC). However, knowledge regarding the biological background of these biomarkers is lacking, which is essential in understanding their role in CRC spread. Methods: Spatial profiling was performed on TD and LNM from 10 CRC patients using 1,800 RNA targets, and segmentation for tumour and tumour microenvironment (TME). From 10 other CRC patients, one TD and LNM were included for filter aided shotgun proteomics, identifying 5,578 differentially expressed proteins. Differences in RNA and protein expression were visualized using heatmaps, volcano plots, and enrichment analyses. Results: Digital spatial profiling showed distinct transcriptome profiles between TD and LNM. The most significant results were found for the TME where TD showed a more tumour support- ive environment (e.g., overexpression of SFRP2, COMP, THBS1, COL11A1, FN1) compared to LNM. Enrichment analyses showed enrichment of focal adhesion, proteoglycans in cancer, and ECM- receptor interaction in the TD (p<0.05), using the KEGG pathways, and the hallmark of epithelial mesenchymal transition (p<0.05), using the Molecular Signatures Databases (MSigDB). The prot- eomics analyses of 10 other CRC patients validated the transcrip- tome results from the digital spatial profiling, with largely over- lapping expression profiles as well as similar enriched pathways. Conclusion: This study shows that TD have a distinct and more invasive phenotype compared to LNM on both the RNA and protein level. The most pronounced differences were found in the TME, which was more pro-tumorigenic in TD. Furthermore, the hallmark of epithelial mesenchymal transition was enriched in TD compared to LNM. These results show that TD are biologically distinct from LNM and give insight into the heterogeneity of different modes of locoregional spread in CRC. OFP-01-010 Extraappendiceal goblet cell carcinoid like amphicrine tumours of GI tract: a long known, not routinely used entity, associated with aggressive behaviour Z.B. Erdem*, H.E. Pasaoglu, E. Yarikkaya, M. Cin, T.B. Özcan, H. Dincer, H. Bektas, N. Dursun Kepkep *Basaksehir Cam and Sakura City Hospital, Turkey Background & objectives: Amphicrine tumours are a rare group of tumours in which single tumour cells coexist both epithelial and neuroendocrine differentiation. This entity is included in the 5th WHO classification of appendiceal tumours, but it is not included in other organ classifications. Methods: Total of 24 gastrointestinal (GI) carcinomas showing amphicrine features reported between January,2016 and Febru- ary,2022 were retrieved from pathology files. Cases that didn’t express at least two neuroendocrine markers and whose appendix weren’t examined for the primary tumour presence (histopatho- logically or radiologically) were excluded from the study. Twenty non-amphicrine GI-carcinomas reported at the same time interval were randomly selected to compare tumour stages. Results: Of the 24 patients 13 were female and 11 were male; mean age was 59 (22 to 72 years). Tumour localizations were S3