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Wilms Tumor




National Wilms Tumor Study Group (NWTS):

The treatment of Wilms tumor (WT) involves a multidisciplinary team. 

  • Surgery is critical for local control
  • Chemotherapy is important to help prevent local recurrence and distant relapse
  • Radiation therapy (RT) can be important to help reduce the risk of local relapse and treat distant metastatic deposits.

Only a few children with WT will be seen in any one center.  Therefore collaborative studies are essential for Wilms.

A major collaborative effort was the National Wilms Tumor Study Group founded in 1969. This cancer research cooperative group set up studies that involved many different treatment centers principally in North America.

NWTS was responsible for major innovations in the treatment of Wilms tumor.

The initial goals of the group were to:

  1. Improve the survival of children with Wilms tumor and other renal tumors
  2. Study the long-term outcome of children treated successfully by identifying the adverse effects of treatment
  3. Study epidemiology and biology of Wilms tumor
  4. Make information regarding successful treatment strategies for Wilms tumor available to physicians around the world

NWTS ran 5 clinical trials, designated NWTS-1 through NWTS-5. The first 4 were randomized trials. The fifth was a clinical trial designed to look primarily at biologic prognostic factors and was not randomized. It was completed in 2003. Currently the group is looking at late effects of treatment.

The studies involved over 250 pediatric oncology treatment centers in the US, Canada, and several other countries. Approximately 70-80% of all patients in the U.S. with Wilms tumor were enrolled on NWTS treatment protocols (in total 440 patients were enrolled annually).


In Europe:

  • Pre-operative Chemotherapy is standard of care.
  • Often the diagnosis may not be confirmed by biopsy and chemotherapy treatment started purely on clinical and radiological grounds.


In North America:

  • Initial nephrectomy is followed by adjuvant chemotherapy.
  • However, in North America preoperative chemotherapy is increasingly used and recommended in certain specific circumstances.


Basis for pre-operative chemotherapy in North America:

Required conditions
  • Massive unresectable unilateral disease

  • Bilateral Wilms tumor

  • Wilms tumor in solitary kidney

  • Tumor thrombus in inferior vena cava


  • Reduce tumor bulk

  • Render disease operable

  • Decrease frequency of tumor rupture at the time of nephrectomy


  • Loss of correct staging information since histologic classification reflects chemotherapy-induced changes


  • Benign lesions or conditions that are not Wilms tumor can occur and may be mistreated


  • False down-staging due to obscure perinephric tumor extensions (changes in histologic pattern, and alteration of eventual stage due to resolution of intra-abdominal metastases)


Treatment Principles

The intensity of treatment depends on:

  • Disease stage
  • Disease histology (UH v FH)
  • Bilateral versus unilateral disease (attempt at maximum preservation of the normal renal parenchyma).


External Links:

Treatment of Wilms Tumor at the National Cancer Institute



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