Factors determining primary or delayed surgery for unilateral, non-metastatic Wilms tumor: a multicentric Egyptian study

Abstract Background There is no consensus on the initial treatment modality for unilateral Wilms tumor (WT) in Egypt. This multicenter study investigates the factors guiding the decision-making between primary surgery and delayed resection for this tumor in our clinical practice. A retrospective analysis was conducted on all patients with unilateral, non-metastatic WT treated at four major Egyptian institutions from January 2019 to January 2024. Clinical characteristics, management details, and outcomes were reviewed. Timing of nephrectomy was analyzed in relation to tumor characteristics such as size, midline crossing, suspicion of perinephric spread, intravascular extension, and retroperitoneal lymphadenopathy. Results The study included 112 patients with a median age of 2.8 years. The median largest tumor diameter was 12 cm (range, 7–16 cm). Primary nephrectomy was performed in 62 patients (55.4%), while 50 (44.6%) underwent delayed resection after biopsy and neoadjuvant chemotherapy. Tumors larger than 12 cm and tumors crossing the midline were reported in 38.5% and 35% of all patients, respectively. Suspicion of perinephric spread was noted in 31% of patients, and significant lymphadenopathy in 13.5%. Intravascular tumor thrombus was detected in 7 patients (6.25%) at various locations. Statistically significant differences were observed between the primary surgery and delayed resection groups regarding suspicion of perinephric spread, intravascular thrombus, and retroperitoneal lymphadenopathy ( p -value < 0.001, 0.002, and < 0.001, respectively). However, tumor diameter and midline crossing showed no significant differences ( p -value = 0.137 and 0.152, respectively). At a median follow-up of 37 months, seven patients experienced relapses, and six died. The 3-year overall and event-free survival for all patients were 91% and 89%, respectively. Conclusions In our study, tumors larger than 12 cm and/or crossing the midline, if without other risk factors, did not significantly influence the decision for primary nephrectomy in unilateral, non-metastatic WT. However, suspicion of perinephric spread, intravascular thrombus (even at the level of renal veins), and evident retroperitoneal adenopathy were crucial factors in choosing delayed resection.