Wilms' Tumor or Nephroblastoma

"The combination of surgery, pre- and post-operative chemotherapy and post-operative radiation therapy has made survival in these patients very high".


What is nephroblastoma?

Wilms' tumor or nephroblastoma is the most frequent solid abdominal tumor in children and is the 5th malignant lesion in childhood (1/200,000 children).

More than 80% of Wilms' tumors appear in children under 5 years old and are very rare in children over 15 years old.

In 20% of affected children there are previously congenital malformations in the urinary tract.

Our Pediatric Cancer Area has more than 25 years of experience and attends to all the malignant pathologies that affect children and adolescents.


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What are the symptoms of Wilms' Tumor?

Wilms' tumor usually manifests itself as a palpable mass in the abdomen. It is usually painless and unilateral.

The abdominal pain, which usually appears in 30% of cases, is usually diffuse. There may be fever or fever and blood loss in the urine (hematuria) that can be macro or microscopic.

Sometimes high blood pressure can appear and this is due to the compression of the tumor on the healthy tissue of the kidney which generates a lack of blood supply (renal ischemia) or increased production of renin.

The most common symptoms are:

  • Painless and unilateral abdominal mass.
  • Diffuse abdominal pain (sometimes).
  • Fever or febricula.
  • Hematuria (bleeding in the urine).
  • High blood pressure.

Do you have any of these symptoms?

You may have a Wilms' Tumor

What are the stages of nephroblastoma?

The stage of the nephroblastoma or Wilms' tumor is established after evaluating the image findings and the results of the surgical piece removed.

Stage I (43% of patients)

  • At this stage the tumor should be limited to the kidney and during surgery it could be completely removed.
  • The renal capsule must be intact, no biopsy was performed prior to removal, and the tumor was not ruptured during surgery.
  • There is no involvement of the renal vessels and no involvement of the lymph nodes.

Stage II (20% of patients)

  • The tumor dries out completely during surgery but there is regional involvement of the tumor.
  • Blood vessels in the region adjacent to the kidney may have tumor cells.
  • No lymph nodes are involved.

Stage III (21% of patients)

  • At this stage there is abdominal tumor involvement.
  • Lymph nodes in the abdomen or pelvis may be involved.
  • The tumor has penetrated the peritoneal surface.
  • If there is tumor debris after surgery or a tumor bleed before or during surgery.

Stage IV (11% of patients)

  • There is blood spread to the lungs, liver, bone or brain, or lymph node metastases outside the abdominal area.

Stage V (5% of patients)

  • There is bilateral affectation.

What is your prognosis for Wilms' Tumor?

Wilms' Tumor is a curable disease in most cases, with tumor survival rates at 5 years above 90%.

The prognosis of these patients will depend:

  • Stage of the tumor at the time of diagnosis.
  • Size of the tumor.
  • Anatomopathological and molecular characteristics of the tumour.
  • Age of the patient (in adolescents and young adults the survival rate is somewhat lower).

How is Wilms' Tumor or Nephroblastoma diagnosed?

Imagen del PET-TAC. Clínica Universidad de Navarra

Wilms' Tumor or Nephroblastoma is a kidney cancer that is diagnosed after a complete medical history and detailed physical examination.

First, a complete blood test and an abdominal ultrasound will be performed, which will show a mass in the kidney of suspicious consistency.

The ultrasound scan is complemented by an abdominal CT scan to find out the size of the tumor, the existence of adenopathy and whether there are any metastases in the liver. A chest CT scan can also be performed to rule out the presence of metastases in the chest or mediastinum.

To complete the diagnostic study, an MRI or a bone scan can be performed to find out if the tumor has spread to other locations. The most frequent metastases, when they occur, are located in the lung, liver and lymph nodes.

Positron emission tomography (PET) with 18F-FDG can provide important information in bilateral tumors or in those patients who receive preoperative chemotherapy and want to evaluate the response to this treatment.

Sometimes, depending on the characteristics found in the imaging studies of the tumor, a biopsy or fine-needle aspiration (FNA) is performed and the anatomopathology of the tumor is analyzed.

How is Wilms' Tumor treated?

The therapeutic approach will depend on the location and extent of the tumor.

For an optimal approach to these children, it is advisable that they be treated by a multidisciplinary team with experience in the treatment of Wilms' tumor (pediatric surgeon or urologist, pediatric oncologist and pediatric radiation oncologist).

In all cases, surgical removal of the tumor will be necessary and of nearby tissues, if involvement is suspected. It is of vital importance to remove the tumor as completely as possible, avoiding its rupture.

The use of coadjuvant radiotherapy (after surgery) and the use of pre- and post-operative chemotherapy has resulted in survival rates of around 80-90%.

Where do we treat it?


The Department of Pediatrics
of the Clínica Universidad de Navarra

All our specialists work exclusively and, in addition, since we have all the technology in the same center, we offer the performance of tests and diagnosis in less than 72 hours.

We have a team of highly qualified professionals to attend the different specialized units: Oncopediatrics, Neuropediatrics, Endocrinopediatrics, Neonatology, etc.

Organized in specialized units

  • Neonatology Area.
  • Pediatric Endocrinology.
  • Pediatric Cardiology.
  • Pediatric Neuropediatrics.
  • Digestive and pediatric nutrition.
  • General and preventive pediatrics.
  • Pediatric Pneumology.
Imagen de la fachada de consultas de la sede en Pamplona de la Clínica Universidad de Navarra

Why at the Clinica?

  • Comprehensive care of the child.
  • Professionals who are experts in the different areas for a better diagnosis and treatment.
  • Equipped with the latest technology for newborn care.

Our team of professionals