ECP 2023 Abstracts

S144 Virchows Archiv (2023) 483 (Suppl 1):S1–S391 13 that did not include intravesical BCG instillation after transurethral resection, and absence of recurrence or a lower number of recur- rences. The presented study identified HIF1α, VEGFR1, NOTCH3 and micro-vessel density as independent prognostic parameters for overall survival and cancer specific survival of patients. NOTCH3 overexpression, greater micro-vessel density, absence of HIF1α and absence of VEGFR1 expression indicate shorter overall and cancer specific survival. Conclusion: Complete clinical data, a comprehensive pathohistologi- cal report, estimation of HIF1 alpha, VEGFR1, NOTCH3 expression and number of CD34 positive micro-vessels on a 2mm biopsy incorpo- rated in tissue microarray could select pT1 patients that require inten- sive follow-up and a trimodal approach to treatment. Understanding the role of molecular pathways in chemio/radiotherapy response could bring new possibilities for better controlling and personalized, molecu- lar treatment of bladder cancer. PS-26-027 Low-grade oncocytic tumour of the kidney – clinical, pathological, and genetic features F. Sánta*, D. Dénes, Á. Somorácz, A. Jenei, G. Fórika, A. Fintha, N. Kránicz, Z. Mészáros, F. Salamon, K. Eizler, N. Giba, D. Semjén, B. Pósfai, A. Sejben, L. Kuthi *University of Szeged, Hungary Background & objectives: Low-grade oncocytic tumour of the kidney (LOT) is a provisional entity categorized as "other oncocytic tumour" in the current World Health Organization classification scheme. In this study, we investigated the clinical, morphological, immunohistochemi- cal, and genetic characteristics of LOT. Methods: LOTs were collected from 6 pathology departments in Hungary. We recorded the demographic, pathological, and survival data. The immunophenotype of the tumours was characterized by CA9, CK7, CK20, CD10, CD117, AMACR, PAX8, GATA3, FH, and SDHB. By the expression of mismatch repair proteins, we defined the microsatellite status. Whole exome sequencing was carried out in 5 cases. Results: We identified 12 LOTs in 7 males and 5 females. The median age was 74 (51-83 years). The median tumour size was 33.5 mm (18- 105 mm). All LOTs were kidney-confined (10 pT1 and 2 pT2). The growth pattern was solid, and the tumours were composed of eosino- philic tumour cells having mild nuclear atypia and perinuclear halos. All cases harboured a CK7-positive and CD117-negative immunophe- notype, furthermore, PAX8, GATA3, FH, and SDHB were diffusely positive in all LOTs. The mismatch repair proteins were retained, indicating a microsatellite stable status. The whole exome sequencing revealed mutations of the TSC1, TSC2, mTOR, and PIK3CA genes. Cancer-specific death was not recorded. Conclusion: In our tumour set, LOT was a rare neoplasm (0.42%), with an excellent clinical course, and it mainly affected old males. LOTs had a unique immunophenotype (CK7+, CD117-, GATA3+), that could be used to discriminate LOTs from other renal neoplasms with eosinophilic cytoplasm. The presence of the mutations of the mTOR/PIK3CA pathway supports that LOT can be a distinct renal tumour entity. Funding: Géza Hetényi Grant, Albert Szent-Györgyi Medical School Research Fund, University of Szeged (5S 340 A202) and New National Excellence Programme (ÚNKP-22-4-SZTE-305). PS-26-028 Prognostic significance of death receptors expression in primary and recurrent T1 bladder cancer S. Stojnev*, M. Krstic, A. Ristic Petrovic, I. Conic, I. Petkovic, J. Todorovic, M. Mladenovic, L. Jankovic Velickovic *University Clinical Centre Nis, Medical Faculty University Nis, Serbia Background & objectives: Stage T1 bladder cancer is a potentially lethal disease with a ten-year progression rate of 40%. A high risk of progression warrants careful endoscopic surveillance. The aim of this study was to assess the prognostic impact of death receptors’ expression. Methods: This study included 224 high grade T1 urothelial blad- der cancers, out of which 168 were primary and 56 recurrent cases. Tumour samples were incorporated in tissue microarrays and ana- lysed by immunohistochemistry for expression of DR4, DR5, and FAS receptor. The expression status of death receptors was correlated with pathological parameters and follow-up data. The median follow-up was 60 months. Results: High expression of DR4, DR5, and FAS was observed in 67%, 72.5%, and 57.1% of the tumours, respectively, and mutually strongly correlated. DR4 was associated with smoking (p=0.045), while FAS expression was more frequent in male patients (p=0.028). FAS stained primary tumours more frequently than recurrent ones (p=0.044). Loss of FAS was significantly associated with cancer- specific death (p=0.046). There was no statistically significant asso- ciation between death receptors expression and overall survival in the whole group. However, after stratification for primary and recurrent tumours, loss of DR4 expression in recurrent tumours was the predic- tor of shorter overall survival (p=0.015). Conclusion: The expression of death receptors may play a significant role in the prediction of T1 bladder cancer prognosis. DR4 loss in recurrent tumours may indicate progression and predict inferior out- come in patients with T1 disease. Death receptors should be included in immunohistochemical biomarkers that require further validation and may potentially aid in personalized decision-making. PS-26-029 Penile squamous cell carcinoma: prognostic impact of p53 immu- nohistochemical expression using a pattern-based framework I. Trias*, R. López, I. Ribera-Cortada, I. De-Torres, C. Ferrándiz, F. Algaba, N. Rakislova *Hospital Clinic de Barcelona, Spain Background & objectives: To analyse the prognostic value of p16 and p53 immunohistochemistry (IHC) in 122 patients with primary penile squamous cell carcinomas (PSCC). Methods: PSCC were classified HPV-associated/HPV-independent based on p16 IHC. p53 IHC was evaluated using “mutated” patterns (diffuse or basal over-expression, null or cytoplasmic staining), and “wild-type” patterns (scattered and mid-epithelial positivity sparing basal layer). Patients were staged using UICC criteria and treated fol- lowing standard protocols. Mean follow-up was 66.7 months (range 7-237). Disease-free survival (DFS) and overall survival (OS) were analysed. Results: Thirty-six tumours (29.5%) were HPV-associated (mean age 67y) and 86 (70.5%) HPV-independent (mean age 69y). p53 IHC showed abnormal pattern suggestive of mutation in 55 tumours:51/86 (59.3%) HPV-independent and 4/36 (11%) HPV-associated tumours (p<0.001). 58 of the patients were stage I tumours, 41 stage II, 15 stage III and 8 stage IV. p16 IHC (HPV status) had no impact on stage, DFS or OS. Stage was related to DFS and OS (p=0.001 and p<0.001, respectively). Abnormal p53 IHC showed impaired OS (p=0.002). Moreover, 9/10 patients (90%) in advanced stage (III/IV) with abnor- mal p53 pattern died of disease, whereas only 2/13 patients (15%) with normal p53 IHC, died of disease (p<0.001). Conclusion: Patients with PSCC showing an abnormal pattern of staining for p53 evaluated using the pattern-based framework, have an impaired prognosis. This association between abnormal p53 and prognosis is particularly strong for patients with advanced stages. p53 could help to define prognosis and to refine treatment strategies for patients with PSCC.