Influence of Pulmonary Nodules on Chest Computed Tomography and Risk of Recurrence in Stage IV Wilms Tumor

Purpose Chest computed tomography (CT) is currently accepted as the main modality for initial disease staging and response assessment in Wilms tumor (WT). However, there is great variability in the number and size of lung metastases at the time of diagnosis and after induction chemotherapy. There is a lack of clinical evidence as to how this variability in tumor burden affects choice of therapy and disease outcome. This study sought to evaluate a previously proposed lung metastases risk stratification system based on CT findings and clinical outcomes in stage IV WT patients. Methods and Materials Thirty-five pediatric patients with a diagnosis of stage IV WT with evaluable pre- and postdiagnosis CT scans between 1997 and 2012 were included in the analysis. Patients were divided into low-, intermediate-, and high-risk categories based on the size and number of pulmonary metastases before and after 6 weeks of chemotherapy. Association of the lung risk groups with lung recurrence-free survival and overall survival at each time point was analyzed with relevant covariates. Results Risk group distribution both at diagnosis and after induction chemotherapy was not influenced by tumor histology. Initial risk grouping suggested an association with disease-free survival at 5 years ( P =.074); however, the most significant correlation was with postinduction chemotherapy disease status ( P =.027). In patients with an intermediate or high burden of disease after 6 weeks of chemotherapy, despite receiving whole-lung and boost irradiation, survival outcomes were poorer. Conclusions Pulmonary tumor burden in stage IV WT on chest CT can predict disease outcome. Patients with intermediate- or low-risk disease, especially after induction therapy, have a higher risk for recurrence. After prospective validation, this method may become a valuable tool in adaptation of therapy to improve outcome.