Prognostic impact of pre‐referral tumor resection in unilateral Wilms tumor: A single‐institute experience from a lower middle‐income country

Introduction The objectives of this study were to evaluate the prognostic impact of pre‐referral surgical resection of Wilms tumor (WT) performed at non‐oncology centers, and to strategize an improved care plan for this very curable pediatric tumor. Methods In this study conducted in a large pediatric cancer center in Pakistan, we retrospectively reviewed the electronic medical records (EMR) of 149 patients with unilateral WT from September 2008 to August 2017. Based on treatment approach, patients were categorized into two groups: (i) pre‐referral tumor resection (PTR: n = 75), and (ii) post‐neoadjuvant chemo nephrectomy (PCN: n = 74). Results The proportion of metastatic disease in PTR and PCN groups was 33.3% and 35.1%, respectively. In the PTR subset, median time to admission after PTR was 5 weeks (mean 11, SEM 2.8, range: 2–202) weeks, with 53.3% (n = 40) presenting more than 4 weeks after PTR. Twenty patients had no cross‐sectional imaging prior to PTR and underwent surgery after abdominal ultrasound only. On baseline imaging at our center, 58.7% (n = 44) of the PTR group had radiologically evaluable disease (four metastases only, 19 local residual tumor only, 21 both localized tumor and visible metastases). Disease staging was uncertain in 23 patients because of no or inadequate histology specimens and/or lymph node sampling in patients with no evaluable disease. Statistically significant differences were recorded for the two subsets regarding tumor volume, extent and nodularity, renal vein and renal sinus involvement, lymph node status, tumor rupture and histopathologic features, and tumor stage, with a 10‐year event‐free survival (EFS) for PCN and PTR of 74.3% and 50.7%, respectively (p