Surgery

The most important role for the surgeon is to ensure complete tumor removal without rupture and assess the extent of disease. Radical nephrectomy and lymph node sampling via a transabdominal or thoracoabdominal incision is the procedure of choice.[228] A flank incision is not performed because it provides limited exposure to the kidney. For patients with resectable tumors, preoperative biopsy or intraoperative biopsy is not performed because either would upstage the tumor in the current COG staging system.[228]

Routine exploration of the contralateral kidney is not necessary if technically adequate imaging studies do not suggest a bilateral process. If the initial imaging studies suggest bilateral kidney involvement, treatment approaches should facilitate renal-sparing surgery.[164]

About 2% of Wilms tumor cases have ureteral involvement. The presence of gross hematuria, nonfunctioning kidney, or hydronephrosis suggests the tumor may extend into the ureter, and cystoscopy is recommended. En bloc resection to avoid tumor spill is recommended.[229]

The surgeon needs to be aware of the risk of intraoperative spill, especially in patients who have right-sided and large tumors, as noted in a review of cases of intraoperative spill among 1,131 patients registered on COG study AREN03B2 (NCT00898365).[230]

Even if stage IV disease (e.g., pulmonary metastases) is evident on imaging, resection of the renal tumor should be considered. Treatment of local stage I or II Wilms tumor in the setting of distant metastasis does not require local radiation therapy.

A solitary kidney.

Predisposition to bilateral tumors. Some children who are predisposed to bilateral tumors and who have very small tumors detected by screening ultrasonography may be considered for renal-sparing surgery to preserve renal tissue.[231]

Horseshoe kidney. Wilms tumor arising in a horseshoe kidney is rare, and accurate preoperative diagnosis is important for planning the operative approach. Primary resection is possible in most cases. Inoperable cases can usually be resected after chemotherapy.[234]

Wilms tumor in infants with Denys-Drash or Frasier syndrome (to delay the need for dialysis).