ECP 2022 Abstract Book

Virchows Archiv (2022) 481 (Suppl 1):S1–S364 13 However we did not find any statistically significant difference concerning the stage T, Nstatus, vascular emboli, perineural invasion and stage. Conclusion: From the onset of the Covid-19 crisis, the politi- cal and the health institutional policies were to avoid delaying management of cancerous pathologies. Our study showed that Covid-19 pandemic clearly affected the prognosis of cancer with significantly increased risk of high grade cases and metastases. This could be explained by the fact that patients avoided seeking for medical assistance for fear to be exposed toCovid-19 in health structures. Further studies are needed to assess the impact of this crisis on the survival of cancer patients. PS-07-049 Prognostic relevance of tumour budding and poorly differenti- ated clusters in gastric adenocarcinoma É. Kocsmár*, L. Szalai, Á. Jakab, I. Kocsmár, I. Szirtes, A. Szi- jártó, Z. Schaff, A. Kiss, G. Lotz *Department of Pathology, Forensic and Insurance Medicine, Sem- melweis University, Hungary Background & objectives: Tumour budding (TBing) is a prognos- tic factor in colorectal cancer and recent studies indicated similar role of poorly differentiated clusters (PDC). However, their prog- nostic value is still controversial in gastric adenocarcinoma (GAC), thus our aim was to determine it. Methods: HE slides of 290 GAC patients was investigated. TB was defined as an isolated tumour cell or a tumour cell cluster of up to four cells, while PDC as a tumour cell cluster of five or more cells. TBs and PDCs were evaluated according to the Inter- national Tumour Budding Consensus Conference and divided into low- (Grade1+2) and high (Grade3) groups. Results: Univariable (Kaplan-Meier) analysis revealed significant negative correlation of both TBing (p=0,0001) and PDCs (p=0,02) with overall survival (OS) in the total cohort and TBing in the intestinal GACs. No significant correlation was found regarding the diffuse and mixed Lauren type GACs. Significant negative cor- relation with OS was also found by multivariable (Cox) analysis of PDCs in the total cohort, moreover in case of both TBing and PDCs in the intestinal type GACs. Logistic regression analysis with back- ward selection showed a significant positive correlation of TBing with the presence of regional lymph node metastasis (p=0.009). Conclusion: Both tumour budding and PDCs are promising prog- nostic markers of gastric adenocarcinomas. High tumour budding is associated with increased risk of nodal metastasis. Funding: This study was partly supported by the New National Excellence Program (ÚNKP-21-4-I-SE-32) of the Ministry for Innovation and Technology, Hungary. PS-07-050 Microsatellite instability status and tumour regression grading on gastric and gastroesophageal junction adenocarcinoma – the first portrait of a Portuguese reality R. Moiteiro da Cruz*, V. Lobo, C. Melo-Alvim, R. Luís *Department of Pathology - Hospital de Santa Maria, CHULN; Faculdade de Medicina da Universidade de Lisboa, Portugal Background & objectives: Locally advanced gastroesophageal junction and gastric adenocarcinoma (GEJGA) usually carry a poor prognosis; a molecular subgroup is associated with microsatellite instability (MSI), whose chemotherapy response has not been well characterized yet. Our aim was to evaluate tumour regression (TR), stratified by MSI status. Methods: A retrospective and unicentric cohort study was assem- bled, encompassing patients submitted to surgery and perioperative chemotherapy (pQT) in 2015-2020. Clinical data regarding pre and post-treatment features, surgical approach, pQT schemes and follow-up was collected. All histological samples were reviewed by two observers; TR grading was reassessed, and mismatch repair proteins (MMRp) expression was evaluated through immunohisto- chemistry on tissue micro-arrays. Results: Out of a total of 64 patients with available tissue samples, only 42 displayed residual tumour. Patients were mostly male (64%), ranging from 60 to 72-years-old (median:67). The series comprised 38,1%(n=16) were moderately differentiated adenocarcinomas and 42.9%(n=18) were poorly differentiated adenocarcinomas (G3) with 14,3%(n=6) were poorly cohesive, the majority of were located in the antrum (n=19); most tumours (57,1%) revealed less than 50% of TR (grade 3). From our sample, 40.5%(n=17) have anomalous MMRp expression and compared with tumours with preserved MMRp expression, the former group showed a statistically significant (p=0.024) worse tumour regression after pQT. However, there was no statistical difference between overall survival (p=0.603) and progression-free survival (p=0.823). Conclusion: In our sample, defective MMRp neoplasms showed worse response to pQT, whereas anomalous and preserved MMRp groups did not seem to differ on prognosis. These new findings in the portuguese context, even if stemming from a limited series, are in line with emerging evidence suggesting the negative role of pQT on MSI tumours and might aid in prompting routine evaluation of MSI on GEJGA for therapy selection in the future. PS-07-051 Duodenal adenoma in familial adenomatous polyposis (FAP), a case series M. Miralles*, C. Fumagalli, T. Vázquez del Olmo, A. Gallardo Alcañiz, M.C. Campos Mármol, A. Prat Cantoral, D. Piñol Ballús, J. Szafranska *Hospital de la Santa Creu i Sant Pau, Spain Background & objectives: Duodenal adenomas are rare tumours which mostly occur in individuals with familial adenomatous poly- posis (FAP) and they can reveal abundant neuroendocrine or Paneth cells’ differentiation. Our goal is to describe clinical and patho- logical differences between sporadic and FAP-associated duodenal adenomas. Methods: Twenty-eight cases of duodenal adenomas diagnosed at our institution (from 2010 to 2022) have been collected. Nine patients (pts) were in FAP (group 1), whilst in the other 19 cases FAP was not clinically suspected (group 2). We revised the histology and performed additional immunohistochemical stains for synaptophysin, chromogranin, CDX2, MUC2, MUC5 and MUC6. Results: The mean age was 44.3 years in group1 and 71.5 years in group2(p=0.001). In group1, 67% of patients were women while in group2 73.7% were men. In both groups, duodenal adenomas were found more frequently in locations other than ampullary (67% and 73.7%, respectively), being multifocal in 56% of group1 and mostly unifocal in group2 (89,5%)(p=0,020). A moderate/high number of Paneth cells was found in 67% of group1, while the vast majority (84.2%) of group2-adenomas had an absence/few Paneth cells(p 0,013). 68.4% of group1-adenomas had moderate/high chromogra- nin expression compared to 31.6% of group2. Another finding was the presence of neuroendocrine hyperplasia in four cases, one of which was in FAP-group. Conclusion: Duodenal adenomas associated with FAP usually occur in younger patients and are frequently multifocal. Histologi- cally, they show a significantly higher number of Paneth cells and S104