ECP 2022 Abstract Book

Virchows Archiv (2022) 481 (Suppl 1):S1–S364 13 PS-26-030 Next generation intraoperative margin assessment in nerve sparing radical prostatectomy, confocal laser microscopy ver- sus frozen sections W. Vreuls*, D. Baas, M. Sedelaar, E. Vrijhof, R. Hoekstra, S. Zomer, G. van Leenders, J. van Basten, D. Somford *CWZ Nijmegen, The Netherlands Background & objectives: Currently frozen section (NeuroSAFE) is the gold standard in intraoperative margin assessment at nerve spar- ing radical prostatectomy (RP), but does have drawbacks. It is time- consuming and laborious. Here we evaluate whether confocal laser microscopy (CLM) could replace NeuroSAFE. Methods: 50 patients underwent a nerve sparing RP with intraopera- tive margin assessment by NeuroSAFE. Concurrently the margins were assessed using CLM by imaging both posterolateral sides using the SamanTree Histolog Scanner. Secondary resection of the nerve bundle was performed when a positive margin was identified by fro- zen section. Results were compared with final pathology. Results: In total 14 out of 96 margins were positive in final pathology. 4 margins were excluded based on macroscopic visible cauterization or neoadjuvant therapy. 1 positive margin was only seen in the final pathology. CLM identified 15 positive margins, 12 of which were seen in the final pathology, for the other 3 deeper levels were necessary to verify that tumour on ink was present. NeuroSAFE identified 14 posi- tive margins, 1 of these was not present in the final pathology. 6 out 14 secondary resections contained tumour, both intraoperative techniques identified these patients. CLM was significantly faster compared to NeuroSAFE (8 vs 50 minutes respectively, p<0.001). Conclusion: This feasibility study demonstrates that surgical mar- gin assessment by CLM at nerve sparing radical prostatectomy is a reliable method compared with the standard technique of intra- operative frozen sections and offers logistical advantages. Both techniques were equally good in identifying those patients that benefitted from resection of the neurovascular bundles. PS-26-031 Rapid intraoperative surgical margin assessment in partial nephrectomy using confocal laser microscopy W. Vreuls*, S. Wagenaar, D. Baas, J. van Basten, S. Dijkstra *CWZ Nijmegen, The Netherlands Background & objectives: Various techniques have been studied in intraoperative margin assessment of partial tumour nephrectomies var- ying from intraoperative ultrasound to frozen section. Here we present a series using a confocal laser microscope (CLM) to assess the surgical margins during robot-assisted partial nephrectomy. Methods: Six patients underwent a partial nephrectomy. Peri-oper- ative parameters were monitored. Once the tumour specimen was removed, it was examined by the pathologist in fresh state, making an assessment of the surgical margin using the Histolog Scanner by SamanTree Medical, Switzerland. The margin and/or the lamellae were scanned after immersion in a contrast agent. Results were compared with final pathology. Results: A total of six tumour specimen from six individual patients were included. The cases contained a spectrum of diagno- sis varying from angiomyolipoma (AML) to clear cell renal papil- lary renal cell carcinoma. In two cases final pathology showed a positive surgical margin, which was visible on the CLM images. Staining time with the contrast agent and image acquisition time was two minutes. The diagnosis of AML was suggested based on the CLM images. Differentiating normal tissue from renal cell carcinoma was possible, but separating various types of renal cell carcinoma was not possible. Conclusion: Intraoperative confocal imaging using confocal laser microscopy is a feasible modality for the assessment of surgical margins from resected kidney tissue during robot assisted partial nephrectomy. Assessment of the surgical margin is easily applica- ble and fast. And potentially adds a diagnostic resolution to exist- ing techniques such as intraoperative ultrasound or gross examina- tion. Validation of the technique is necessary and its added value in clinical practice needs to be established. PS-26-032 GRIN3A – a novel biomarker identifying a subtype of intra- ductal prostate cancer (IDC-P) M. Bogaard*, J.M. Strømme, S.G. Kidd, B. Johannessen, A.C. Bak- ken, R.A. Lothe, K. Axcrona, R.I. Skotheim, U. Axcrona *Oslo University Hospital & University of Oslo, Norway Background & objectives: The molecular background contributing to the poorer prognosis of a cribriform pattern (invasive cribriform (ICC) and/or intraductal carcinoma (IDC-P)) in prostate cancer is still largely unexplored. Therefore, we aimed to identify molecular markers specific for a cribriform pattern. Methods: Utilizing RNA-sequencing, we compared cribriform to non-cribriform Gleason pattern 4 (GP4; N=13), and genes with expression significantly associated with cribriform pattern were identified. Among these, ACSM1 , GRIN3A , PCDHB2 and REG4 were selected for validation in a larger cohort (N=85) using RT- PCR. RNA in situ hybridization (RNAscope®) on tissue micro- arrays (N=479) was used to assess gene expression related to histopathology. Results: Ten genes were significantly upregulated and 144 genes downregulated in cribriform pattern samples. Of the selected upregulated genes ( ACSM1 , GRIN3A , PCDHB2 and REG4 ), only GRIN3A was significantly higher expressed in cribriform pattern samples when compared to non-cribriform GP4 samples in a larger cohort (p=0.005). In relation to histopathology, GRIN3A was more frequently identified in tissue cores with IDC-P (54%) followed by ICC (32%) and non-cribriform GP4 (29%) from tumours with a cribriform pattern compared to non-cribriform GP4 (20%) from tumours without any cribriform pattern (all p<0.01). GRIN3A was identified in benign tissue in 0.5% of samples. Conclusion: In this relatively large prostate cancer patient series, GRIN3A was identified as an RNA-based biomarker for the pres- ence of a cribriform pattern in prostate cancer and specifically a subtype of IDC-P. Furthermore, GRIN3A was idenitifed as a tumour marker, as it only rarely identified in benign tissue. Additional studies are needed to elucidate the functional role of GRIN3A in tumours with a cribriform pattern and whether it may be used in diagnostic setting. Funding: The study was supported by the South-Eastern Nor- way Regional Health Authority (grant numbers: 2019016 and 2020063), the Research Council of Norway through its FRIPRO funding scheme (262529/F20 and Toppforsk-250993), and the Norwegian Cancer Society (grant number 208197). The study was granted secure storage of computer files and high-per- formance computation resources from NorStore and Univer- sity of Oslo’s Services for Sensitive Data (NS9013S and p19, respectively). PS-26-033 Immunoreactivity of CK7 in clear cell renal cell carcinomas G. Miranda*, J. dos Santos, J. Correia-Pinto, D. Alves, T. Amaro *Unidade Local de Saúde de Matosinhos - HPH, Portugal S176