Timing of Radiation Therapy in Pediatric Wilms Tumor: A Report From the National Cancer Database

Purpose: To determine, using the National Cancer Database (NCDB), the impact of the surgery to radiation therapy interval (SRI) on survival in contemporary patients with Wilms tumor (WT). Methods and Materials: The NCDB was queried for patients aged <= 25 years diagnosed from 2004 to 2013 with unilateral WT who underwent definitive surgery and radiation therapy. The SRI was calculated for each patient. A stratified analysis was performed based on presence of metastasis using logistic regression to calculate risk factors for prolonged SRI, with a focus on the recommended SRI according to recent Children's Oncology Group trials (by day 14) and National Wilms Tumor Study-5 (by day 9). Cox regression was performed to assess the association of SRI with overall survival. Results: A total of 1488 patients were included; 32.1% had metastasis at diagnosis. Among both metastatic and nonmetastatic groups, older patients were more likely to have prolonged SRI. For those without metastasis, SRI > 14 days was associated with increased risk of mortality (hazard ratio 2.13, P=.013). Analyzing SRI as a continuous variable also demonstrated an increased risk of death with longer SRI (hazard ratio 1.04 per day, P=006) in this group. In contrast, among patients with metastasis, no significant association between SRI and mortality was found. Conclusion: Early initiation of radiation therapy remains a critical component of multimodal treatment for patients with nonmetastatic WT. For nonmetastatic patients, SRI <= 14 days correlates with improved overall survival. However, no such association was noted for patients with metastases. These results may inform the development of future WT trials. (C) 2018 Elsevier Inc. All rights reserved.