The management of bilateral Wilms tumor (BWT) is challenging, particularly due to its presentation at a younger age, rarity, and difficulty for treatment decisions and surgical evaluation comparing to unilateral WT. In this study, the outcome of BWT patients from a single center who were treated by the Turkish Pediatric Oncology Group (TPOG) Wilms Tumor Regimen were retrospectively reviewed. From 1990 to 2016, 30 patients with synchronous BWT were treated with a preoperative chemotherapy of vincristine and actinomycin-D (VA). Chemotherapy was continued until safe nephron sparing surgery (NSS) could be performed for as long as radiological tumor response continued; otherwise, the chemotherapy was intensified by adding doxorubicin (D) alternating with VA every 6 weeks. The median followup of patients was 59 months (4-297 months). The median duration of preoperative chemotherapy was 81 days and ranged between 14 days and 198 days. Preoperative chemotherapy was modified in seven patients (23%) to the VAD regimen. Twenty-two patients (73%) had a radical nephrectomy on the larger tumor and NSS on the contralateral kidney, and 6 patients (20%) had bilateral NSS. Postoperative tumor stages for stage I, II and III were 60%, 22% and 14%, respectively. The 5-year event free survival (EFS) rates were 100%, 90% and 51% for stages I, II and III (p=0.02), respectively. Unfavorable histology and nephrogenic rests were reported in 20% and 20% of patients, respectively. The 5-year overall survival (OS) and EFS rates were 50% and 25%, respectively, in patients with anaplasia, while the same rates were 96% and 96% in patients with favorable histology tumors (p=0.05 and p < 0.001). The 10-year EFS and OS rates for all patients were 82% and 86%, respectively. Our results are comparable with the literature. VA is effective as initial preoperative treatment of BWT and allows for safe resection.

Keywords: bilateral Wilms tumor, nephron sparing surgery, preoperative chemotherapy, synchronous