Abstract
BACKGROUND: An inferior vena cava thrombus (IVCT) occurs in approximately 4-10% of Wilms tumor (WT) cases. The presence of an IVCT complicates surgical management and potentially affects patient outcomes. We reviewed all patients with a WT with and without an IVCT treated at our center, comparing their characteristics and outcome. PATIENTS AND METHODS: We retrospectively reviewed pediatric patients with a WT treated between November 2014 and July 2023. Patients were categorized according to the presence or absence of an IVCT. Data on demographics, clinical presentation, imaging findings, treatment modalities, and outcomes were collected. Group comparisons for categorical data were carried out using Chi-square tests, Event-free survival (EFS) and overall survival (OS) were estimated using Kaplan-Meier curves, and differences between groups were assessed with the log-rank test. RESULTS: Among 110 children with a unilateral WT, 17 (15.4%) had an IVCT at presentation. Their median age at diagnosis was 4.2 years. Females predominated (65%) and 11 (65%) had distant metastasis. Thrombus levels were infra-hepatic (52.9%), retro-hepatic (23.6%), supra-hepatic (5.9%), and intra-cardiac (17.6%). Thrombus resolution following neo-adjuvant chemotherapy was achieved in 41.2% of patients, most frequently in infra-hepatic thrombi. Local control followed neo-adjuvant chemotherapy that included doxorubicin. Favorable histology was observed in 70% of patients with an IVCT. Compared with patients without an IVCT, children with an IVCT tend to present at an older age, have hematuria, a larger tumor, positive lymph node (LN) involvement, and metastatic disease (p value, 0.019, 0.008, 0.01, 0.014, and 0.002, respectively). On univariable analysis, older age, the presence of metastatic disease, IVCT, LN involvement, and diffuse anaplasia were associated with inferior EFS and OS. Five-year EFS and OS were significantly lower in patients with IVCT compared to those without (51% ± 12.5% vs. 74.5% ± 4.6%, p = 0.021 and 53.8% ± 15.4% vs. 82% ± 4.9%, p = 0.012, respectively). CONCLUSIONS: We observed a higher proportion of IVCT than previously reported. Consistent with prior studies, an IVCT was associated with more aggressive disease features. Although survival was worse in patients with an IVCT, the mere presence of a thrombus as an independent prognostic factor requires evaluation in larger patient cohorts.