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INTRODUCTION AND OBJECTIVES: According to the pediatric oncology cooperative groups, the recommended surgical management for patients with non-syndromic unilateral Wilms tumor (uWT) is radical nephrectomy. However, data from adult renal malignancies demonstrate that when oncologically feasible, nephron-sparing surgery (NSS) decreases long-term chronic renal disease and associated co-morbidities. In order to study this in pediatric renal tumors we assembled an international collaboration of interested investigators.

METHODS: We retrospectively reviewed cases of children with non-syndromic uWT managed with attempted NSS. Data was collected on: demographics, oncologic characteristics and outcomes, medical and surgical therapy, and serum Creatinine (Cr, mg/dL). Estimated Glomerular Filtration Rate (eGFR, mL/min/1.73m2) was calculated via the Schwartz formula. Pre and posttherapy measures were compared with a Wilcoxon signed-rank test.

RESULTS: We identified 13 patients (5F:8M) diagnosed at a median age of 2.01yr (0.2-8.1) followed for 8.7yr (0.24-31.8). All patients had a solitary mass with a median tumor volume (TV) at diagnosis of 59.0mL (2.7-640). 5 patients (38.5%) received pre-surgical chemotherapy and in those we observed a median total and percent TV reduction of 26.7mL (2.13-70.2) and 62.6% (15-77), p = 0.043. After accounting for TV reduction, the median TV at surgery for our entire cohort was 21.0mL (2.7-640). All patients underwent NSS. Staging was: 9 Stage I, 2 Stage II and 2 Stage III (1 case done as an enucleation and 1 with a positive lymph node). Final pathology showed negative surgical margins and favorable histology WT in all specimens. During follow up there was 1 local recurrence (7.7%) in a Stage II patient after 1.9yr which was salvaged with chemotherapy and radiation. There was one death from chemotherapy-related sepsis in a Stage III patient after 0.24yr. The median pre-operative Cr and eGFR were 0.5 (0.22-1.0) and 88.2 (39.4-151.4), respectively. The median Cr and eGFR at last follow-up were 0.6 (0.29-1.1) and 131.8 (57.5-180.0), respectively. During follow up, there was a statistically-significant change in eGFR with a median increase of 32.2 (0.9-83.0), p = 0.002.

CONCLUSIONS: We observed that, in a highly selected patient population, NSS for non-syndromic uWT offers reasonable oncologic outcomes and outstanding long-term renal function preservation. This requires future prospective and controlled investigation on a large scale, hopefully in collaboration with the pediatric oncology cooperative study groups.
Source of Funding: None