## Wilms Tumor: Prognostic Factors and Treatment Strategy ### Histologic Prognostic Factors **Key Point:** Favorable histology (epithelial, mixed, stromal) accounts for ~90% of Wilms tumors and carries 5-year survival >85%. Anaplastic histology (diffuse or focal) is associated with 5-year survival <50% and requires more intensive therapy. ### Staging and Treatment Approach | Stage | Definition | Treatment Strategy | | --- | --- | --- | | I | Tumor confined to kidney | Nephrectomy + adjuvant chemotherapy (no RT for favorable histology) | | II | Tumor extends beyond kidney but completely resected | Nephrectomy + adjuvant chemotherapy ± RT | | III | Incomplete resection or regional spread | Neoadjuvant chemotherapy, then surgery, then adjuvant therapy | | IV | Hematogenous or lymphatic metastases | Intensive multimodal therapy | | V | Bilateral renal involvement | **Nephron-sparing approach** preferred | **High-Yield:** Bilateral Wilms tumor (Stage V) is present in 5–10% of cases. Modern treatment emphasizes **nephron-sparing surgery** with chemotherapy and selective radiotherapy to preserve renal function, NOT immediate bilateral nephrectomy. **Clinical Pearl:** The goal in bilateral disease is to perform partial nephrectomy or chemotherapy-first approach to preserve at least one functioning kidney and avoid lifelong dialysis dependence. ### Molecular Prognostic Markers **Key Point:** Loss of heterozygosity (LOH) at chromosomes 1p and 16q is a powerful adverse prognostic marker, associated with 5-year survival <50% in Stage I favorable histology tumors. This guides intensification of chemotherapy regimens. **Mnemonic:** **LOH = Loss Of Hope** — chromosomal losses 1p/16q predict poor outcome and warrant aggressive treatment.
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