A 2-year-old boy has an abdominal mass detected incidentally. CT scan shows a large left renal mass with both solid and cystic components, contained within the renal capsule. No metastases are identified. Biopsy confirms Wilms tumor (nephroblastoma). According to the Children's Oncology Group (COG) staging system, this is Stage I. What is the treatment protocol?
- A Neoadjuvant chemotherapy (as per SIOP protocol) before nephrectomy
- B Radiation therapy to the flank followed by radical nephrectomy
- C Immediate nephrectomy followed by chemotherapy with vincristine and actinomycin D (EE-4A regimen) ✓
- D Chemotherapy with vincristine, actinomycin D, and doxorubicin for 6 months
Correct answer: C. Immediate nephrectomy followed by chemotherapy with vincristine and actinomycin D (EE-4A regimen)
Explanation
The North American COG approach for Wilms tumor begins with upfront nephrectomy followed by adjuvant chemotherapy based on pathology and stage. For Stage I favorable histology Wilms tumor, the EE-4A regimen (vincristine + actinomycin D for 18 weeks) is standard without radiation. The SIOP (European) protocol uses pre-operative chemotherapy to shrink the tumor before surgery. Understanding the difference between COG and SIOP approaches is commonly tested. Stage I favorable histology has >95% 4-year survival with appropriate treatment.
Reference: Ghai Essential Pediatrics, 10th ed.
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Written and medically reviewed by the StethoPrep medical team.