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

Abstract

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.