Wilms tumor

Epidemiology
Most common pediatric renal tumor
450 cases per year
Age: 3 to 4 years

Risk factors
WAGR syndrome (Wilms tumor, aniridia, GU abnormalities, mental retardation)
Denys-Drash syndrome (Wilms tumor, pseudohermaphroditism, renal failure)
Beckwith-Wiedemann syndrome (hemihyperptrophy)

Pathology
WT1: tumor suppressor gene (located at 11p13)
 -abnormal in 82% of Wilms patients with a congenital syndrome
 -WT1 mutations are more rare in sporadic cases
WT2: mutated in Beckwith-Wiedemann syndrome

Clear cell sarcoma and rhabdoid tumor of the kidney are pediatric tumors that do not represent true Wilm's: rhabdoid tumor of the kidney may be related to ATRT

Prognostic factors
Stage
Histology: anaplastic Wilms (diffuse anaplasia is worse than focal)
LOH @ 1p or 16q

Clinical
Flank mass, hypertension, hematuria
Only 5-10% of tumors are calcified (calcified flank masses are much more likely to be neuroblastoma)

Therapy
Surgery only if:
-Patient less than 2 years old
-Stage I (confined to kidney and completely resected without spillage or biopsy)
-Tumor weighs less than 550g
-Favorable histology

Surgery + chemo if:
-Stage I, any of above criteria not fulfilled
-Any Stage II (extends beyond kidney with complete resection)

Surgery + chemo + RT if: 
-Stage II, unfavorable histology (flank gets 10.8Gy)
-Stage III (residual disease), favorable histology (flank gets 10.8Gy)
-Stage III with diffuse anaplasia/RTK (flank gets 19.8Gy)
-Spillage or intra-abdominal tumor implants (whole abdomen gets 19.8Gy)
-Lung mets (12Gy whole lung irradiation, current COG protocol eliminates WLI if pt obtains a rapid complete response to chemo)
-Liver mets (19.8Gy to whole liver)
-Bone mets (25.2Gy)

Bilateral (stage V):
Induction chemo
Nephron sparing surgery if at all possible