Toronto Staging Guidelines for Wilms Tumour: The Meeting Point Between Clinicians and Epidemiologists—Results of the BENCHISTA-ITA Project

Background/Objectives: Despite overall excellent outcomes for Wilms tumour, regional variations in stage at diagnosis and care pathways remain a concern across Europe. We evaluated stage distribution, three-year survival, and treatment patterns in Italy, considering hospital care as a proxy for healthcare capacity and migration. Methods: Data were obtained from 26 population-based cancer registries (PBCRs), covering 148 patients (ages 0–14) diagnosed between 2013 and 2017, representing about 80% of the Italian population. Stage was classified according to the Toronto guidelines. Information on treatment and diagnosed/treating hospitals was collected. Stage at diagnosis was further refined using probabilistic linkage with the clinical registry 1.01 Model. Overall survival, defined as all-cause mortality, was estimated using the Kaplan–Meier method. Results: Most patients presented with localized disease (77%), 32% Stage I, while 19% were Stage IV. Three-year survival analysis showed significant differences between stages, ranging from 98% in patients with Stage I to 78% in the ones with Stage IV. No significant disparity across the Italian regions was observed in stage distribution or survival. Diagnoses and treatments were mostly (>90%) centralized in the same region for patients residing in the Centre or North of Italy. However, the cross-regional health migration from the South was of about 30% for diagnosis and larger for treatments. Conclusions: This study shows that standardized staging improves data comparability and highlights challenges in managing metastatic cases and regional care pathways. The results support the use of clinical and PBCR information to interpret survival patterns and guide improvements in paediatric oncology care.