Laparoscopic Treatment of Wilms' Tumor: Criteria of SIOP-UMBRELLA Protocol may be Updated.

Introduction: Total nephrectomies for the treatment of Wilms' tumor (WT) are more and more performed by laparoscopy, although indications for this approach following the UMBRELLA guidelines are currently very restrictive. The purpose of this study was to assess the compliance to the criteria of the UMBRELLA protocol for minimally invasive approach of WT.

Methods: This retrospective multicenter study included children operated on by laparoscopic total nephrectomy for suspected WT before 2020. Imaging was reviewed centrally.

Results: Fifty-six patients (50 WT and 6 nephrogenic rests) were operated on at a median age of 3.3 ± 2.6 years. Thirteen (23%) patients had metastasis at diagnosis. The mean operative time was 213 ± 84 min. There were eight (14.3%) conversions and five peroperative complications. A local stage III was confirmed in seven (12.5%) cases, including two for tumor rupture. Only one (1.8%) of the procedures followed the SIOP-UMBRELLA indications for laparoscopy. The criterion "ring of normal parenchyma" was met only once. Conservative surgery seemed possible in ten (17.9%) cases. The extension of the tumor beyond the ipsilateral edge of the vertebra after chemotherapy and a volume over 200 mL were associated with an increased risk of conversion (p = 0.0004 and p = 0.001 respectively). After a mean follow-up of 5.2 ± 4.0 years, although there was no local recurrence, one death occurred due to metastatic progression at 15 months postoperatively.

Conclusions: The laparoscopic approach of WT beyond the UMBRELLA recommendations was feasible with low risk of local recurrence. Its indications may be updated and validated.