Use of Nephron Sparing Surgery and Impact on Survival in Children with Wilms Tumor: A SEER Analysis

Purpose: Nephron sparing surgery is the standard of care for many adults with renal tumors and has been described in some children with Wilms tumor. However, beyond case series the data concerning nephron sparing surgery application and outcomes in patients with Wilms tumor are scarce. We examined nephron sparing surgery outcomes and factors associated with its application in children with Wilms tumor. Materials and Methods: We retrospectively reviewed the 1998 to 2010 SEER database. We identified patients 18 years old or younger with Wilms tumor. Clinical, demographic and socioeconomic data were abstracted, and statistical analysis was performed using multivariate logistic regression (predicting use of nephron sparing surgery limited to unilateral tumors smaller than 15 cm) and Cox regression (predicting overall survival) models. Results: We identified 876 boys and 956 girls with Wilms tumor (mean +/- SD age 3.3 +/- 2.9 years). Of these patients 114 (6.2%) underwent nephron sparing surgery (unilateral Wilms tumor in 74 and bilateral in 37). Median followup was 7.1 years. Regarding procedure choice, nephron sparing surgery was associated with unknown lymph node status (Nx vs N0, p < 0.001) and smaller tumor size (p < 0.001). Regarding survival, only age (HR 1.09, p = 0.002), race (HR 2.48, p = 0.002), stage (HR2.99, p < 0.001) and lymph node status (HR2.17, p = 0.001) predicted decreased overall survival. Survival was not significantly different between children undergoing nephron sparing surgery and radical nephrectomy (HR 0.79, p = 0.58). Conclusions: In children with Wilms tumor included in the SEER database nephron sparing surgery has been infrequently performed. Nephron sparing surgery application is associated with smaller, bilateral tumors and with omission of lymphadenectomy. However, there are no evident differences in application of nephron sparing surgery based on demographic or socioeconomic factors. Despite lymph node under staging, overall survival is similar between patients undergoing nephron sparing surgery and radical nephrectomy.