Bilateral Wilms Tumor: Multi-institutional analysis of nephron-sparing surgery at centers with focused wilms tumor expertise.

Abstract

Purpose: The proportion of children who undergo bilateral nephron-sparing surgery (BNSS) for bilateral Wilms tumor (BWT) is variably reported. We evaluated the frequency of BNSS versus unilateral radical nephrectomy with contralateral nephron-sparing surgery (NSS) at institutions with focused Wilms tumor expertise during the Children's Oncology Group (COG) AREN0534 era. We hypothesized that BNSS would be performed more frequently than the 35% frequency reported on AREN0534.

Methods: We identified the top 10 enrolling institutions (all renal tumors) on the COG Renal Tumor Banking Study (AREN03B2) during the AREN0534 enrollment period and before publication of AREN0534 results. Six institutions participated in this multi-institutional retrospective cross-sectional study of children presenting with BWT from 2009 to 2017. Data on the index surgical procedure for each kidney were collected.

Results: Sixty-four children with BWT were included. BNSS was performed in 45/64 (70.3%; 95% CI, 58-81%), while 19/64 (29.7%) underwent unilateral radical nephrectomy with contralateral NSS; no child underwent bilateral radical nephrectomy as their index surgical procedure. BNSS frequency varied by institution, chemotherapy exposure, and local stage. On multivariable analysis, increasing age at surgery was independently associated with lower odds of BNSS (OR 0.62/year, 95% CI 0.39-0.94). At a median follow-up of 111 months, recurrence-free and overall survival did not differ between groups.

Conclusion: Institutions with focused Wilms tumor expertise achieved BNSS in 70% of children with BWT during the AREN0534 era, substantially exceeding the frequency reported on AREN0534 and supporting efforts to maximize nephron preservation when oncologically appropriate.