RT Journal Article SR Electronic T1 SENECA study: staging endometrial cancer based on molecular classification JF International Journal of Gynecologic Cancer JO Int J Gynecol Cancer FD BMJ Publishing Group Ltd SP 1313 OP 1321 DO 10.1136/ijgc-2024-005711 VO 34 IS 9 A1 Chacon, Enrique A1 Boria, Felix A1 Lyer, R Rajagopalan A1 Fanfani, Francesco A1 Malzoni, Mario A1 Bretová, Petra A1 Luzarraga Aznar, Ana A1 Fruscio, Robert A1 Jedryka, Marcin A A1 Tóth, Richard A1 Perrone, Anna Myriam A1 Kakkos, Athanasios A1 Cristóbal Quevedo, Ignacio A1 Congedo, Luigi A1 Zanagnolo, Vanna A1 Fernandez-Gonzalez, Sergi A1 Ferro, Beatriz A1 Narducci, Fabrice A1 Hovhannisyan, Tatevik A1 Aksahin, Elif A1 Cardenas, Laura A1 Oliver, M Reyes A1 Nozaleda, Gonzalo A1 Arnaez, Marta A1 Misiek, Marcin A1 Ferrero, Annamaria A1 Pain, Flore Anne A1 Zarragoitia, Janire A1 Diaz, Cristina A1 Ceppi, Lorenzo A1 Mehdiyev, Shamsi A1 Roldán-Rivas, Fernando A1 Guijarro-Campillo, Alberto Rafael A1 Amengual, Joana A1 Manzour, Nabil A1 Sanchez Lorenzo, Luisa A1 Núñez-Córdoba, Jorge M A1 Gonzalez Martin, Antonio A1 Minguez, Jose Angel A1 Chiva, Luis A1 YR 2024 UL http://ijgc.bmj.com/content/34/9/1313.abstract AB Objective Management of endometrial cancer is advancing, with accurate staging crucial for guiding treatment decisions. Understanding sentinel lymph node (SLN) involvement rates across molecular subgroups is essential. To evaluate SLN involvement in early-stage (International Federation of Gynecology and Obstetrics 2009 I–II) endometrial cancer, considering molecular subtypes and new European Society of Gynaecological Oncology (ESGO) risk classification.Methods The SENECA study retrospectively reviewed data from 2139 women with stage I–II endometrial cancer across 66 centers in 16 countries. Patients underwent surgery with SLN assessment following ESGO guidelines between January 2021 and December 2022. Molecular analysis was performed on pre-operative biopsies or hysterectomy specimens.Results Among the 2139 patients, the molecular subgroups were as follows: 272 (12.7%) p53 abnormal (p53abn, 1191 (55.7%) non-specific molecular profile (NSMP), 581 (27.2%) mismatch repair deficient (MMRd), 95 (4.4%) POLE mutated (POLE-mut). Tracer diffusion was detected in, at least one side, in 97.2% of the cases; with a bilateral diffusion observed in 82.7% of the cases. By ultrastaging (90.7% of the cases) or one-step nucleic acid amplification (198 (9.3%) of the cases), 205 patients were identified with affected sentinel lymph nodes, representing 9.6% of the sample. Of these, 139 (67.8%) had low-volume metastases (including micrometastases, 42.9%; and isolated tumor cells, 24.9%) while 66 (32.2%) had macrometastases. Significant differences in SLN involvement were observed between molecular subtypes, with p53abn and MMRd groups having the highest rates (12.50% and 12.40%, respectively) compared with NSMP (7.80%) and POLE-mut (6.30%), (p=0.004); (p53abn, OR=1.69 (95% CI 1.11 to 2.56), p=0.014; MMRd, OR=1.67 (95% CI 1.21 to 2.31), p=0.002). Differences were also noted among ESGO risk groups (2.84% for low-risk patients, 6.62% for intermediate-risk patients, 21.63% for high–intermediate risk patients, and 22.51% for high-risk patients; p<0.001).Conclusions Our study reveals significant differences in SLN involvement among patients with early-stage endometrial cancer based on molecular subtypes. This underscores the importance of considering molecular characteristics for accurate staging and optimal management decisions.All data relevant to the study are included in the article or uploaded as supplementary information.