Wilms' tumor surgery
Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]
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Overview
Surgery is the mainstay of treatment for wilms' tumor.
Surgery
The following operative principles have also evolved from NWTS trials:
- 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. A flank incision is not performed because it provides limited exposure to the kidney. For patients with resectable tumors, preoperative or intraoperative biopsy is not performed because it potentially upstages the tumor.
- 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 are suggestive of bilateral kidney involvement, treatment approaches should facilitate renal-sparing surgery.
- About 2% of Wilms tumors 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.
- 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).
Renal-sparing surgery remains controversial and is not recommended, except for children with the following:
- Predisposition to bilateral tumors. Some children who are predisposed to bilateral tumors and who have very small tumors detected by ultrasound screening may be considered for renal-sparing surgery to preserve renal tissue.
- A solitary kidney.
- 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.
- Wilms tumor in infants with Denys-Drash or Frasier syndrome (to delay the need for dialysis).
The use of renal-sparing surgery for bilateral tumors is under investigation.
Renal-sparing surgery does not appear to be feasible in most patients at the time of diagnosis because of the location of the tumor within the kidney, even in those with very low risk. In North America, renal-sparing surgery (partial nephrectomy) of unilateral Wilms tumor following administration of chemotherapy to shrink the tumor mass is considered investigational.
Hilar and periaortic lymph node sampling is appropriate even if the nodes appear normal. Furthermore, any suspicious node basin is sampled. Margins of resection, residual tumor, and any suspicious node basins are marked with titanium clips.
Wilms tumor rarely invades adjacent organs; therefore, resection of contiguous organs is rarely indicated. There is an increased incidence of complications occurring in more extensive resections that involve removal of additional organs beyond the diaphragm and adrenal gland. This has led to the recommendation in current COG protocols that these patients should be considered for initial biopsy, neoadjuvant chemotherapy, and then secondary resection. Primary resection of liver metastasis is not recommended.