Wilms' tumor staging

Overview
Staging is determined by combination of imaging studies, and pathologic findings if the tumor is operable (adapted from www.cancer.gov). Treatment strategy is determined by the stage:

Stage I (43% of patients)
For stage I Wilms' tumor, 1 or more of the following criteria must be met:
 * Tumor is limited to the kidney and is completely excised.
 * The surface of the renal capsule is intact.
 * The tumor is not ruptured or biopsied (open or needle) prior to removal.
 * No involvement of renal sinus vessels.
 * No residual tumor apparent beyond the margins of excision.

Treatment: Nephrectomy + 18 weeks of chemotherapy Outcome: 98% 4-year survival; 85% 4-year survival if anaplastic

Stage II (23% of patients)
For Stage II Wilms' tumor, 1 or more of the following criteria must be met:
 * Tumor extends beyond the kidney but is completely excised.
 * No residual tumor apparent at or beyond the margins of excision.
 * Any of the following conditions may also exist:
 * Tumor involvement of the blood vessels of the renal sinus and/or outside the renal parenchyma.
 * The tumor has been biopsied prior to removal or there is local spillage of tumor during surgery, confined to the flank.

Treatment: Nephrectomy + abdominal radiation + 24 weeks of chemotherapy

Outcome: 96% 4-year survival; 70% 4-year survival if anaplastic

Stage III (23% of patients)
For Stage III Wilms' tumor, 1 or more of the following criteria must be met:
 * Unresectable primary tumor.
 * Lymph node metastasis.
 * Positive surgical margins.
 * Tumor spillage involving peritoneal surfaces either before or during surgery, or transected tumor thrombus.

Treatment: Abdominal radiation + 24 weeks of chemotherapy + nephrectomy after tumor shrinkage

Outcome: 95% 4-year survival; 56% 4-year survival if anaplastic

Stage IV (10% of patients)
Stage IV Wilms' tumor is defined as the presence of hematogenous metastases (lung, liver, bone, or brain), or lymph node metastases outside the abdomenopelvic region.

Treatment: Nephrectomy + abdominal radiation + 24 weeks of chemotherapy + radiation of metastatic site as appropriate

Outcome: 90% 4-year survival; 17% 4-year survival if anaplastic

Stage V (5% of patients)
Stage V Wilms’ tumor is defined as bilateral renal involvement at the time of initial diagnosis. Note: For patients with bilateral involvement, an attempt should be made to stage each side according to the above criteria (stage I to III) on the basis of extent of disease prior to biopsy. The 4-year survival was 94% for those patients whose most advanced lesion was stage I or stage II; 76% for those whose most advanced lesion was stage III. Treatment: Individualized thereapy based on tumor burden

Stage I-IV Anaplasia
Children with stage I anaplastic tumors have an excellent prognosis (80-90% five-year survival). They can be managed with the same regimen given to stage I favorable histology patients.

Children with stage II through stage IV diffuse anaplasia, however, represent a higher-risk group. These tumors are more resistant to the chemotherapy traditionally used in children with Wilms’ tumor (favorable histology), and require more aggressive regimens.