Survival Impact of Cytoreductive Surgery in FIGO Stage IVB Endometrial Cancer: A Population-Based Study

<b>Background:</b> The impact of cytoreductive surgery on survival in patients with FIGO stage IVB endometrial cancer remains controversial. This study aimed to evaluate the independent effect of surgery within contemporary multimodal treatment strategies using a large population-based registry. <b>Patients and methods:</b> We conducted a multicenter retrospective analysis of 6582 patients with endometrial cancer recorded in the Saxony-Anhalt cancer registry between 2000 and 2020. After exclusions, 294 patients with FIGO stage IVB disease were included. Disease-free survival (DFS) was the primary outcome and overall survival (OS) the secondary outcome. Patients were initially categorized into three treatment groups: surgery only, non-surgical therapy, and combined multimodal therapy. To address potential selection bias, a propensity score-based inverse probability of treatment weighting (IPTW) analysis was performed to compare surgery versus no surgery. Time-period subgroup analysis was conducted for 2000-2010 and 2011-2019. <b>Results:</b> The median follow-up was 68 months (range 0-265 months). Combination therapy resulted in significantly improved median DFS and OS compared to surgery or non-surgical therapy alone. After IPTW adjustment, surgery was independently associated with improved OS (HR 0.64, 95% CI 0.53-0.78, <i>p</i> < 0.01) and DFS (HR 0.67, 95% CI 0.48-0.94, <i>p</i> = 0.02). Subgroup analysis demonstrated a significant survival benefit of surgery in the contemporary period (2011-2019), whereas the effect was weaker and not statistically significant in the earlier period (2000-2010). <b>Conclusions:</b> Cytoreductive surgery is independently associated with improved survival in patients with FIGO stage IVB endometrial cancer, particularly within modern therapeutic eras. These findings support the integration of surgery as part of a multimodal approach in selected patients while highlighting the importance of refined patient selection in the context of evolving systemic therapies.