Initial Treatment for Wilms Tumor
The initial treatment for Wilms tumor consists of upfront surgical resection (nephrectomy) followed by adjuvant chemotherapy, with radiation therapy added for higher stages of disease.
Diagnostic Approach
- Wilms tumor (nephroblastoma) is the most common primary renal tumor in children
- Diagnosis typically involves:
- Abdominal imaging (ultrasound, CT, or MRI)
- Complete blood count
- Renal function tests
- Chest imaging to assess for metastatic disease
Treatment Algorithm
Step 1: Initial Surgical Management
- Primary nephrectomy is the standard first-line approach in North America 1
- The National Wilms' Tumor Study Group recommends primary surgery before any adjuvant treatment 2
- Complete tumor resection with radical nephrectomy is the goal
- Careful examination of the contralateral kidney is essential during surgery
- Lymph node sampling is required for accurate staging
Step 2: Histological Classification and Staging
- Favorable histology (FH) vs. unfavorable histology (anaplastic)
- Staging system:
- Stage I: Tumor limited to kidney, completely excised
- Stage II: Tumor extends beyond kidney but completely excised
- Stage III: Residual non-hematogenous tumor confined to abdomen
- Stage IV: Hematogenous metastases (lung, liver, bone, brain)
- Stage V: Bilateral renal involvement
Step 3: Adjuvant Therapy Based on Stage and Histology
- Stage I and II (FH): Vincristine and actinomycin D for 18-24 weeks 2
- Stage III (FH): Vincristine, actinomycin D, and doxorubicin plus radiation therapy
- Stage IV (FH): Vincristine, actinomycin D, and doxorubicin with radiation to metastatic sites
- Unfavorable histology: More intensive regimens with additional agents
Alternative Approach: European Protocol
- The International Society of Pediatric Oncology (SIOP) recommends preoperative chemotherapy followed by nephrectomy 2
- This approach has shown to:
- Reduce tumor size before surgery
- Decrease risk of intraoperative tumor rupture
- Downstage the tumor in some cases
Special Considerations
- Bilateral Wilms tumor (Stage V): Requires nephron-sparing approaches with initial biopsy, preoperative chemotherapy, and delayed surgical resection to preserve renal function 3
- Tumor rupture: Higher risk with immediate nephrectomy (13.5%) compared to delayed nephrectomy after chemotherapy (5.2%) 4
- Vincristine: FDA-approved for use in Wilms tumor as part of combination therapy 5
Treatment Outcomes
- Overall survival exceeds 90% for children with favorable histology Wilms tumor who receive appropriate treatment 1
- The combination of surgery, chemotherapy, and when needed, radiation therapy has led to excellent outcomes
- Survival rates of 84.5% have been reported in single-center studies 4
Potential Complications and Monitoring
- Monitor for tumor lysis syndrome, especially in large tumors
- Chemotherapy-related toxicities include myelosuppression, hepatic veno-occlusive disease with actinomycin D
- Long-term surveillance for second malignancies is necessary, particularly in patients who received radiation therapy
The multidisciplinary approach involving pediatric surgeons, oncologists, radiologists, and pathologists has been key to the successful treatment of Wilms tumor, making it one of the success stories in pediatric oncology.