ECP 2023 Abstracts

S106 Virchows Archiv (2023) 483 (Suppl 1):S1–S391 13 the recurrence-free survival. We found a correlation between the rate of TILs<50% and the lymphatic invasion(p=0.022), the high grade of the tumour(p=0.02) and the tumour size>3cm(p=0.009). Conclusion: ILs represent an important prognostic and predictive factor for stage II CC. It should be introduced in clinical practice, to identify patients with "high risk" stage II CC, justifying the benefit of adjuvant chemotherapy. PS-17-011 In-house validated approach of gastric cancer: a tool for a better evaluation of HER2 heterogeneity S. Gurzu*, C. Satala, Z. Kovacs, I. Jung *George Emil Palade University Of Medicine, Pharmacy, Sciences And Technology Of Târgu Mureş, Romania Background & objectives: As HER2 is a target for therapy with tras- tuzumab, different methodologies were proposed for detection of HER2 expression/amplification. The aim of this study is to present the chal- lenges encountered by pathologists in evaluation of HER-2 expression in gastric cancer. Methods: In 90 consecutive gastro-oesophageal adenocarcinomas, HER2 immunophenotype was checked with the polyclonal antibody c-ErbB-2 (HER2) from Dako (dilution 1:800). To test the tumour heterogeneity, three different slides were stained for each case, two from tumour core, and one from invasion front. Fluorescence in situ hybridization (FISH) was done in cases with equivocal results. Results: In 6 of the seven cases with HER2 3+ expression, the three sections showed diffuse positivity, in both core and front. One of the cases revealed 2+ equivocal result in the front, with further HER2 amplification. In 5 cases equivocal HER2 (2+) was seen in tumour tissue sampled from tumour core. Three out of the five cases presented low HER-2 (1+) in the front and no FISH amplification. After exami- nation of the 10 cases with low HER2 (1+) in both core and front, no differences were observed between the two tumoral areas. One of the cases was amplified. The other 68 cases did not express HER2 and were predominantly dedifferentiated. Conclusion: HER2 heterogeneity should be checked in the tumour core, using at least two full slides per case, especially for tumours that show equivocal results (2+). Further data needs to elucidate the prognostic or therapeutic impact of low HER2 in gastric cancer. This research was funded by George Emil Palade University of Medicine, Pharmacy, Science and Technology, Targu Mures, Romania - grant num- ber 10127/13/17.12.2020. PS-17-012 IL-17-positive cells in gastric cancer M. Hadzhi*, P. Petkova, K. Dinkova, M. Gulubova *Dept. General and clinical pathology, Trakia University, Medical Faculty, Bulgaria Background & objectives: Gastric cancer is one of the most common cancers. IL-17 is produced by Th17 cells but also by innate T-cell subsets such as T regulatory cells, CD8 T cells, NK T cells, γδ T-cells, NK cells, neutrophils and eosinophils. Methods: The study includes 32 operated gastric cancer patients. We used immunohistochemistry with antibodies against IL-17, chromogra- nin A and tryptase, and combined staining with toluidine blue and IL-17. Results: The IL-17-positive immune cells has been counted in the invasive front (IF), tumour stroma (TS), and in tertiary lymphoid struc- tures (TLS). MCs-positive for IL-17, tryptase and toluidine blue are detected. IL-17-positive endocrine cells (EC) have been observed in antral, corpus mucosa and in some tumour cells. Conclusion: We demonstrate that the IL-17 tumour-promoting cytokine is secreted not only by innate immune cells and mast cells but also by IL-17+ ECs. New investigation are necessary to determine the precise mechanisms of IL-17 production and the connection of Th17 cells, MCs and ECs in gastric cancer development. PS-17-013 Ki67 is a good prognosis marker in colorectal carcinoma S. Hidouri*, M. Walha, D. Jamai, S. Aloulou, A. Khabir, K. Bel Hadj Ali, M. Hamdani *Department of Pathology, Habib Bourguiba University Hospital, Medenine, Tunisia Background & objectives: Colorectal cancer (CRC) with same stage has different behaviour. Using a score based on staining intensity and frequency, we analysed the prognostic value of ki67-expression in Tunisian CRC and we addressed its expression relation with patient survival and clinicopathological factors. Methods: One hundred CRC-patient were enrolled in this study col- lected from the pathology department of Medenine during six years. The immuno-histo-chemistry study was performed with pre-diluted antibodies on multi-tissue blocks prepared from well-targeted donor blocks. For statistical reasons, Ki67 expression was sub-grouped into four groups referring to the Allred score as used in breast carcinoma. The data was analysed on SPSS-software. Results: The proliferative index was more than 75% in 40% of cases. Allred score was between 5 and 8 in 70 cases. Ki67’over-expression was more frequent in case of absence or low percentage of metastatic lymph-node and in case of stage I and II with respective p 0.028 and 0.01. It was more observed in the presence of a minority poor progno- sis component with a p = 0.05. An inverse significant correlation was observed in the presence of venous (p=0.02) and lymphatic (p=0.02) vascular invasion and with the abundance of stroma lymphocyte infil- trate (p=0.01). Overall survival at 5 years was better in patients with Ki67score ≤ 4, without statistically significant differences. Conclusion: Tumours with same stage are heterogeneous if measured by proliferative index. Intra-tumoral LI has not been reported in series studying Ki67 expression in CCR. We report for the first time a signifi- cant and inverse correlation with the abundance of the LI. Explaining their better prognosis, tumour cells with high proliferative activity are more sensitive to chemo-radiotherapy and they cause an imbalance between "proapoptotic" and "anti-apoptotic" signals. PS-17-014 Cyclin D1 is a good prognostic biomarker in colorectal carcinoma S. Hidouri*, M. Walha, D. Jamai, S. Aloulou, K. Bel Hadj Ali, A. Khabir, M. Hamdani *Department of Pathology, Habib Bourguiba University Hospital, Medenine, Tunisia Background & objectives: Colorectal cancer (CRC) with same stage has different behaviour. We analysed the prognostic value of Cyclin D1-expression in CRC Tunisian-patients. Using a score based on stain- ing intensity and frequency, we addressed Cyclin D1 expression relation with patient-survival and clinicopathological factors. Methods: One hundred patients with CRC were enrolled in this study collected from the pathology department of Medenine during 6 years. The immunohistochemistry study was performed with pre- diluted antibodies on multi-tissue blocks prepared from well-targeted donor blocks. For statistical reasons, the expression of Cyclin D1 was dichotomized into "negative" or "positive". The data was analysed on SPSS software. Results: Cyclin D1 was positive in 42 cases. pT1-pT2 tumours had a clear tendency to express Cyclin D1(p = 0.090). For lymph nodes, two inverse significant correlations were found with lymph-node stage (p=0.02) and with the percentage of metastatic lymph node (p=0.008). Two additional significant negative correlations were observed with