In stage IV Wilms tumor (11% of patients), hematogenous metastases (lung, liver, bone, brain), or lymph node metastases outside the abdominopelvic region are present. The presence of tumor within the adrenal gland is not interpreted as metastasis and staging depends on all other staging parameters present. The primary tumor should be assigned a local stage following the above criteria which determines local therapy. For example, a patient may have stage IV, local stage III disease.
Stage V and those predisposed to developing Wilms tumor
In stage V Wilms tumor (5% of patients), bilateral involvement by tumor is present at diagnosis. Previously an attempt was made to stage each side according to the above criteria on the basis of the extent of disease. The current COG-AREN0534 protocol recommends preoperative chemotherapy in hopes of reducing tumor size to allow renal-sparing surgical procedures. In these patients, renal failure rates approach 15% at 15 years posttreatment, making renal-sparing treatment important.
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Breslow NE, Collins AJ, Ritchey ML, et al.: End stage renal disease in patients with Wilms tumor: results from the National Wilms Tumor Study Group and the United States Renal Data System. J Urol 174 (5): 1972-5, 2005.