ECP 2022 Abstract Book

Virchows Archiv (2022) 481 (Suppl 1):S1–S364 13 perineural invasions (P =.0009). The 3-year DFS and the 5-year OS rates for Bd (1 versus 2-3) was of 79.4% versus 67.2% (P=.001) and 89.2% versus 80.8% (P=.001), respectively. This was confirmed after adjustment for relevant clinicopathological features for DFS (HR, 1.41; 95% CI, 1.12 to 1.77; P =.003) and OS (HR, 1.65; 95% CI 1.22 to 2.22; P = .001). When combined with pTN stage and Immunoscore subgroups, Bd significantly improved disease prognostication. Conclusion: Bd demonstrated its independent prognostic value for DFS and OS. Given these findings, Bd per the ITBCC 2016 should be mandatory in every pathology report in stage III CC patients. Bd and Immunoscore could play a complementary role in personalized healthcare in this setting. Funding: We thank the GERCOR team, the PRODIGE investiga- tors and the National Cancer Institute (INCa) for funding the trial. OFP-02 | Joint Oral Free Paper Session Gynaecological Pathol- ogy / Cytopathology OFP-02-001 Consensus based recommendations for the diagnosis of Serous Tubal Intraepithelial Carcinoma; an international Delphi study J. Bogaerts*, M. van Bommel, M. Steenbeek, R. Hermens, J. de Hullu, J. van der Laak, M. Simons *Radboud University Medical Centre, The Netherlands Background & objectives: Diagnosis of Serous Tubal Intraepi- thelial Carcinoma (STIC), a precursor lesion to high-grade serous carcinoma, has moderate reproducibility. We aim to inventory cri- teria for STIC diagnosis among gynaecopathologists and formulate consensus based recommendations. Methods: We invited 70 gynaecopathologists to a 3 round Delphi study. The first round consisted of open ended questions concern- ing their diagnostic process. The answers of round 1 were used to formulate 64 statements. In the subsequent rounds, participants were asked to rate their level of agreement with these statements, using a 9-point Likert-scale, ranging from fully disagree to fully agree. Results: Gynaecopathologists participating in this study (n=34, 49%) scored 64 statements, subdivided in topics: tissue handling, morphologi- cal criteria, immunohistochemical staining and reporting recommenda- tions. Consensus was reached for 27/64 (42%) statements, such as: each fallopian tube has to have the fimbriated end fully embedded; nuclear pleomorphism, nuclear enlargement, high nuclear to cytoplasmatic ratio and nuclear hyperchromasia are morphological criteria that need to be present for diagnosing STIC; P53 and Ki67 staining only have to be performed in case a STIC is considered based on morphology; WT1, CyclinE, STMN1 and p16 have no added value in diagnosing STIC. Conclusion: We describe current practices concerning STIC diag- nostics among 34 gynaecopathologists and present a list of 27 rec- ommendations based on consensus vote. Consistent and reproduc- ible STIC diagnostics is important, as it holds prognostic value for individual patients. Moreover, it is a prerequisite to safely offer alternative risk reducing surgical interventions to women who are at an increased risk of ovarian carcinoma within the protection of a clinical trial. The recommendations from this study contribute to further standardization of the diagnostic process. Funding: Funded by the Dutch Cancer Society (KWF Kankerbestrijding) OFP-02-002 Endocervical endometrioid adenocarcinoma: clinicopathologic characterisation of a rare human papillomavirus-independent tumour type A. Hodgson*, S. Stolnicu, C. Mateoiu, T. Kiyokawa, A. Felix, H. Trihia, L. De Brot, G. Karpathiou, R. Soslow, C. Parra-Herran, W.G. McCluggage, K.J. Park *Toronto General Hospital, Canada Background & objectives: Endocer vical endometr ioid adenocarcinoma (EEA) is a rare human papillomavirus (HPV)- independent tumour type included in the 2020 World Health Organization Classification of cervical adenocarcinoma. Due to its apparent rarity, this entity has been poorly characterised in the literature to date. Methods: EEAs that fulfilled the following strict criteria were col- lected from multiple institutions: presence of confirmatory endo- metrioid features; surgically treated; exclusion of endometrial or ovarian origin; negative high risk HPV by in situ hybridization or polymerase chain reaction. Demographic, pathologic and follow up information, if available, was recorded for each case. Results: There were 14 patients with a median age of 56 years (range 30-74 years). Endometriosis and areas of mesonephric(-like) differentiation were seen each in 2 cases (one tumour had both). 4/14 tumours demonstrated evident squamous differentiation/meta- plasia. The median tumour size was 3.6 cm (4 tumours 2-3.9 cm and 6 tumours ≥ 4 cm, range 0.8 to 8.6 cm). All were at least stage IB1 (FIGO 2018). Initial nodal involvement was seen in 2/13 patients and recurrence (14 months, liver; 60 months, paraaortic nodes) in 2/11 patients (follow up median 46 months, range 2-192 months). Oestrogen receptor expression was at least focal in 13/14 tumours while all showed non-diffuse p16 expression. Conclusion: This endeavour represents the largest reported series of EEA. Diligent sampling, comprehensive microscopic examina- tion and ancillary studies for detection of HPV are essential to establish the correct diagnosis. Additional studies are needed to determine the molecular pathogenesis and optimal management for these neoplasms and to compare their clinicopathologic behaviour with other endocervical adenocarcinoma types. OFP-02-003 QPOLE; a rapid, simple and cheap approach for POLE assess- ment in endometrial cancer by multiplex qPCR A. van den Heerik*, N. Ter Haar, L. Vermij, J. Jobsen, M. Brinkhuis, S. Roothaan, A. Leon-Castillo, G. Ørtoft, E. Hogdall, C. Hogdall, T. van Wezel, L. Lutgens, E. van der Steen-Banasik, J.N. McAlpine, C. Creutzberg, V. Smit, B. Gilks, N. Horeweg, T. Bosse *Radiation Oncology, Leiden University Medical Center, The Netherlands Background & objectives: Detection of pathogenic POLE -muta- tions in endometrial cancer is of prognostic and therapeutic impor- tance. Currently, POLE -status is determined by DNA-sequencing, which is time-consuming, not widely available and expensive. We validated a rapid, low-cost quantitative polymerase-chain-reaction (qPCR) assay for pathogenic POLE -mutations; QPOLE . Methods: Primer and fluorescence-labelled 5’-nuclease probe- sequences of pathogenic POLE -mutations within the POLE exo- nuclease domain were designed. Two multiplex mixes, QPOLE - frequent for the most occurring mutations (P286R, V411L, A456P, S459F) and QPOLE -rare for the rare variants (M295R, F367S, D368Y, L424I, P436R, M444K) were developed using DNA extracted from formalin-fixed paraffin-embedded tumour tissues from our extensive EC tumour tissue repository. Results: Cut offs for POLE -wild type, -mutant and failed results were predefined based on 50 POLE -wild types and 7 POLE -mutant cases. For cases with values in the equivocal range between wild type and mutant, additional DNA-sequencing (i.e. Next Generation Sequencing (NGS)) is recommended. In our testing set of 227 cases S6