Primary nephrectomy and intraoperative tumor spill: Report from the Children's Oncology Group (COG) renal tumors committee

Abstract

Purpose Initial Children’s Oncology Group (COG) management for Wilms’ tumor (WT) consists of primary nephroureterectomy with lymph node sampling. While this provides accurate staging to define further treatment, it may result in intraoperative spill (IOS), which is associated with higher recurrence rates and therefore requires more intensive therapy. The purpose of this study is to determine current rates and identify factors which may predispose a patient to IOS. Methods The study population was drawn from the AREN03B2 renal tumor banking and classification study of the Children’s Oncology Group. All children with a first time occurrence of a renal mass were eligible for the study. At the time of enrollment and prior to risk stratification, the institution is required to submit operative notes, pathology specimens, a chest computed tomography scan (CT), and a contrast-enhanced CT or magnetic resonance imaging (MRI) of the abdomen and pelvis for central imaging review. These data are then used to determine an initial risk classification and therapeutic protocol eligibility. Patients who had a unilateral nephroureterectomy for favorable histology WT underwent further review to assure data accuracy and to clarify details regarding the spill. Analyses were performed using chi square and logistic regression. Odd ratios (OR) are shown with 95% confidence intervals. Results There were 1,131 primary nephrectomies for unilateral WT with an IOS rate of 9.7% with an additional 1.8% having possible tumor spill during renal vein or IVC tumor thrombectomy. IOS correlated with diameter (>12cm, p<0.0001) and laterality (right, p=0.0414). Simple logistic regression indicated that IOS increased 2.7% [p=0.0240, OR 1.027 (1.004, 1.052)] with each 1 cm increase in diameter (3 –21cm) and 4.7% [p=0.0147 OR 1.047 (1.009, 1.086)] with each 100 g increase in weight (80 – 1800 g). Multiple logistic regression indicated that laterality [right p=0.048, OR 1.46 (1.004, 2.110)] and weight (p=0.03, OR 1.039 (1.003, 1.075) were predictive of IOS when diameter was included as a continuous variable. Diameter as a binary variable was highly prognostic of IOS (p=0.0002), while laterality and weight were not significant. Conclusions Intraoperative tumor spill occurs in about one out of every ten cases of primary nephroureterectomies for WT. Right-sided and larger tumors are at higher risk of IOS.

Feasibility of using CT volume as a predictor of specimen weight in a subgroup of patients with low risk Wilms tumors registered on COG Study AREN03B2: Implications for central venous catheter placement

“…Our findings support our earlier published findings of a linear relationship between CT derived WT volume and WT weight within 1131 of the first 2000 patients enrolled in COG AREN03B2 who underwent a primary unilateral nephrectomy for favorable histology and which included a wider range of WT sizes and patient ages [7]. These updated findings are derived from a cohort of patients ≤2 years of age and a pathological diagnosis of Stage I, FH WT.…”

Current surgical standards of care in Wilms tumor

“…WTs can be hypervascular and have large areas of necrosis that may predispose to rupture; thus, careful handling of the tumor is needed. Intraoperative tumor rupture occurs in approximately 9% of procedures and is associated with tumors more than 15 cm [7].…”

Customized approach for upfront or delayed resection using radiological criteria in unilateral, nonmetastatic pediatric renal tumors: A prospective study

“…However, this approach is blemished by the risk of intraoperative tumor rupture. The rupture rates across the National Wilms Tumor Study (NWTS) studies have ranged from 33% in earlier studies to 11% from the latest AREN03B2 study . Tumor rupture upraises the disease to stage III, which results in significant augmentation of therapy compared to that in stage I or II.…”