Prognostic Determinants of Survival, Relapse, and Chemoresistance in Unilateral Wilms Tumor: A 10-Year Real-World Cohort Study from the Caucasus Region

Background Although survival outcomes for unilateral Wilms tumor (WT) are generally favorable, clinically meaningful heterogeneity persists across risk groups, and real-world evidence on the prognostic value of treatment-response dynamics remains limited. Comprehensive cohort data from the Caucasus–Central Asia region are also scarce. We aimed to evaluate survival outcomes and identify prognostic determinants in a 10-year single-center SIOP-treated cohort from this underrepresented setting. Methods We retrospectively analyzed 59 consecutive pediatric patients with unilateral WT treated according to SIOP protocols between 2010 and 2020. Response to pre-operative chemotherapy was assessed by standardized abdominal ultrasonography criteria. Overall survival (OS) and disease-free survival (DFS; time from diagnosis to relapse or death, whichever occurred first) were estimated using Kaplan–Meier methods, and prognostic factors were evaluated using Cox proportional hazards regression. Results The median age at diagnosis was 4.3 years, and most patients presented with Stage II–III disease. Pre-operative chemotherapy resulted in regression in 84.7% of cases, stable disease in 8.5%, and progression (chemoresistance) in 6.8%. Median follow-up was 89 months. One-, three-, and five-year OS rates were 96%, 92%, and approximately 88–90%, respectively, and median OS was not reached. Relapse events clustered early, with ~ 80% occurring within the first 24 months; median DFS was 19–21 months. In Cox analyses, Stage III–IV disease and chemoresistance were strongly associated with inferior OS and DFS (p < 0.05). Thrombocytopenia was also associated with worse OS and DFS, while neutropenia was associated with relapse risk. Conclusions This study provides one of the first large real-world unilateral WT datasets from the Caucasus–Central Asia region and offers implementation-focused evidence relevant to other resource-constrained settings. We confirm an early relapse window (≤ 24 months) and highlight the prognostic relevance of ultrasound-defined progression during pre-operative therapy (chemoresistance) within a standardized SIOP framework. Associations between hematologic toxicity markers and outcomes suggest that routinely available clinical parameters may complement conventional risk factors and help refine risk assessment and follow-up prioritization.