Wilms Tumor (Nephroblastoma): Causes, Symptoms, Treatment and Prognosis — Overview, Diagnosis & Treatment Options | MyMedicPlus

Wilms tumor (nephroblastoma) is the most common malignant kidney tumor in children, accounting for approximately 95% of pediatric kidney cancers, with peak incidence at ages 3-4. Approximately 500 new cases occur per year in the US. Bilateral Wilms tumor (Stage V, 5-10% of cases) implies hereditary predisposition and requires nephron-sparing surgical approaches.

WT1 tumor suppressor gene mutations on chromosome 11p13 are present in approximately 15% of cases. Associated genetic syndromes: WAGR syndrome (Wilms, Aniridia, Genitourinary anomalies, intellectual disability), Denys-Drash syndrome (WT1 mutation causing nephrotic syndrome and GU anomalies), and Beckwith-Wiedemann syndrome (11p15 overgrowth syndrome). Most Wilms tumors are sporadic.

Palpable asymptomatic abdominal or flank mass is the most common presentation, often discovered by parents during bathing. Abdominal pain, gross hematuria, hypertension (from renin secretion), fever, and anemia may occur. Sudden increase in abdominal girth from tumor hemorrhage. Unlike neuroblastoma, Wilms tumor rarely crosses the midline.

Abdominal ultrasound is the first-line imaging modality, followed by CT chest/abdomen/pelvis for staging. MRI provides superior delineation for bilateral tumors and tumor thrombus. Chest CT for pulmonary metastases (most common site). NWTS/COG staging (I-V). Biopsy is performed only for bilateral disease or unresectable tumors to determine histology (favorable versus anaplastic) before chemotherapy.

North American COG approach: primary nephrectomy without prior chemotherapy, then risk-adapted adjuvant chemotherapy (Stage I-II favorable histology: vincristine plus actinomycin D; Stage III-IV or unfavorable histology: add doxorubicin; Stage III-IV: plus abdominal radiation). European SIOPE approach: preoperative chemotherapy (vincristine-actinomycin D) to shrink tumor, then nephrectomy. Bilateral Wilms (Stage V): preoperative chemotherapy followed by bilateral nephron-sparing surgery.

Wilms tumor is among the most curable pediatric cancers. Overall 4-year OS exceeds 90%. Stage I favorable histology: 4-year OS approximately 99%. Stage IV (metastatic) favorable histology: approximately 86%. Unfavorable histology (diffuse anaplasia): Stage IV approximately 55-65%. Bilateral Wilms (Stage V): approximately 80% OS with nephron-sparing surgery and chemotherapy.