Guideline · Oct 2019
In brief
In brief
Clinical reference handbook from the Children's Oncology Group covering diagnosis, staging, and treatment protocols for pediatric renal tumors including Wilms tumor and other nephroblastomas.
Written by the GCMD Library team from the guideline.
Staging Classification for Renal Tumors
Defines five stages for Wilms tumor and related renal tumors: Stage I (tumor confined to kidney, completely resected), Stage II (tumor extends beyond kidney but completely resected), Stage III (residual abdominal disease including lymph node involvement or spillage), Stage IV (hematogenous metastases), and Stage V (bilateral renal involvement). Renal cell carcinoma uses TNM staging system with different criteria based on tumor size, vascular invasion, and nodal involvement.
General Surgical Principles for Unilateral Disease
Transperitoneal approach with radical nephrectomy and lymph node sampling is standard for Stages I-IV. Flank incisions are contraindicated due to inadequate exposure and increased spillage risk. Contralateral kidney exploration is not required if preoperative imaging is normal, but bilateral involvement must be ruled out if imaging suggests lesions.
Surgical Management of Bilateral Wilms Tumor
Primary nephrectomy is discouraged at diagnosis for Stage V disease. Upfront three-drug chemotherapy is initiated, with reassessment at 6 weeks for possible surgery if less than 50% tumor reduction occurs or tumor is resectable. Open renal biopsies are recommended only for non-responding tumors after chemotherapy, using posterior approach to minimize peritoneal contamination.
Tissue Handling and Specimen Processing
Specimens must be sent fresh and intact to pathology without bivalving or disrupting the capsule in the operating room. Rapid processing within 20 minutes is essential for biology studies. Coordination between surgical, laboratory, and clinical personnel is critical for proper specimen handling.
Lymph Node Sampling Requirements
Routine lymph node sampling from renal hilum and paraaortic/paracaval regions is mandatory for accurate staging and eligibility for surgery-only protocols. Formal lymph node dissection is not recommended, but involved or suspicious nodes must be excised and labeled separately. Documentation of lymph node status is critical for treatment stratification.
Tumor Biopsy and Spillage Guidelines
Routine preoperative tumor biopsy is contraindicated as it results in Stage III designation and requires additional chemotherapy and radiation therapy. Biopsy should only be performed when tumor is deemed unresectable, using posterior approach when possible. Any tumor spillage (local or diffuse), rupture, or removal in multiple pieces constitutes Stage III disease and determines radiation field extent.
Management of Vascular Extension
Renal vein and inferior vena cava involvement occurs in 11% and 5% of cases respectively. Tumor thrombus extending above hepatic veins or to the atrium should receive preoperative chemotherapy to facilitate resection. En bloc removal is preferred when feasible; cardiopulmonary bypass may be required for atrial extension.
Surgical Approach to Metastatic Disease
Suspicious intra-abdominal or hepatic lesions should be biopsied at exploration to confirm metastatic disease. Small pulmonary nodules (<1 cm) should be biopsied as one-third may not be metastatic; thoracoscopic resection is recommended for peripheral lesions. Residual pulmonary disease at Week 6 determines need for whole lung radiation.
Management of Initially Unresectable Tumors
Initial exploration is recommended to assess operability before preoperative chemotherapy, as imaging alone risks under- or over-staging. Tumors are considered unresectable if vena caval thrombus extends above hepatic veins, removal requires resection of contiguous organs (spleen, pancreas, colon), or nephrectomy would cause significant morbidity. Preoperative chemotherapy typically renders tumors resectable while preserving adjacent organs.
Surgical Management of Relapse After Surgery-Only Protocol
Local recurrence after very low-risk surgery-only protocol requires biopsy confirmation and complete imaging. Resection should be performed if feasible, followed by chemotherapy using Regimen DD4A. Residual disease after Week 6 chemotherapy should be reassessed for resection at Week 12, with rebiopsy strongly encouraged if resection remains infeasible.