RT Journal Article SR Electronic T1 EP171/#796  The need for lymph node evaluation in late-stage uterine carcinosarcoma – a multicenter retrospective study JF International Journal of Gynecologic Cancer JO Int J Gynecol Cancer FD BMJ Publishing Group Ltd SP A147 OP A147 DO 10.1136/ijgc-2023-IGCS.261 VO 33 IS Suppl 4 A1 Wang, Yaokai A1 Peng, Juan A1 Liu, Lizhou A1 Liu, Bei A1 Li, Xian A1 Lau, Suk A1 Kwok, Shuk A1 Chu, Mandy A1 Ngu, Siew Fei A1 Chan, Karen A1 Zhang, Li A1 Ngan, Hextan A1 Tse, Ka YR 2023 UL http://ijgc.bmj.com/content/33/Suppl_4/A147.2.abstract AB Introduction Uterine carcinosarcoma (UCS) is a highly aggressive, rare, biphasic tumor.Lymph node evaluation by either lymphadenectomy (LND) or sentinel lymph node biopsy(SLNB) is recommended. However, its value in late-stage disease remains unclear.Methods Clinical data of patients with UCS from four different hospitals between February 2006 and December 2021 were reviewed. Patients with prior radiotherapy and/or chemotherapy were excluded. Progression-free survival (PFS) and overall survival (OS) were determined.Results Among 103 UCS patients, 91 UCS patients had enough follow-up data. 47 (51.6%) were diagnosed at stage III-IV, among which 24 (51.1%) had LND. 16 patients (34.0%) had lymph node metastases (LNM). Patients undergoing LND was associated with longer median PFS (20.2 months vs. 5.7 months, P = 0.009) and OS (29.1 months vs. 14.1 months, P < 0.009) compared to those without LND. Multivariate analyses demonstrated that LND (hazard ratio, HR 0.447, 95% confidence interval (CI) 0.23 – 0.86, P = 0.-16) and chemotherapy (HR 0.070, 95% CI 0.03 – 0.19, P < 0.001) were significant prognostic factors for PFS in late-stage patients. Additionally, LND (HR 0.133, 95% CI 0.04 – 0.50, P =0.003) and chemotherapy (HR 0.102, 95% CI 0.03 – 0.33, P < 0.001) were independent significant prognostic factors for OS.Conclusion/Implications Despite the use of adjuvant therapy, LND remains an integral part of the surgical treatment. Further prospective studies are needed to elucidate its value in late-stage disease.