What Is Wilms Tumor?

Medically Reviewed on 12/18/2020
Wilms tumor or nephroblastoma is a type of kidney cancer that primarily develops in children
Wilms tumor or nephroblastoma is a type of kidney cancer that primarily develops in children

Wilms tumor or nephroblastoma is a type of kidney cancer that primarily develops in children around the ages of three and four years. It’s the most common type of kidney cancer found in kids. Wilms tumor is a serious cancerous tumor that may affect one or both kidneys. It may also spread (metastasize) to other parts of the body. There are two types of Wilms tumors that are classified by how they look microscopically:

  • Favorable histology: It means that while the tumor cells are not normal, they aren’t too large or distorted, and the patient will typically have a better prognosis.
  • Anaplastic histology: It means that the cancer cells vary greatly and have large, distorted nuclei. This is called anaplasia and is harder to treat than tumors with favorable histology.

Causes:

  • Most cases of Wilms tumors are considered sporadic (occur by chance) and are the result of genetic mutations that affect cell growth in the kidney. These mutations generally arise after birth, but in some cases, children are born with a genetic alteration that predisposes them to cancer.

Signs and symptoms:

  • The most common symptom is a swollen abdomen, which is usually painless. Sometimes, a parent or carrier may feel a lump in the abdomen, which can be quite large.
  • Occasionally, the tumor may bleed slightly, and this can irritate the kidney and may be painful.
  • There may be blood in the child’s urine, or their blood pressure may be raised.
  • The child may also have a fever (a high temperature), upset stomach, weight loss, or a lack of appetite.

Diagnosis:

  • An abdominal ultrasound scan is usually the first thing that is done.
  • A magnetic resonance imaging (MRI) and/or computed tomography (CT) scan of the abdomen and chest are done.
  • Urine and blood samples will also be taken to check the patient’s kidney function and general health.
  • Most children will go on to have a biopsy, where a sample of tissue is taken from the tumor to confirm the diagnosis.

Staging:

A commonly used staging system for Wilms tumor is described below:

  • Stage 1: The tumor is only affecting the kidney and has not begun to spread. It can be completely removed with surgery.
  • Stage 2: The tumor has begun to spread beyond the kidney to nearby structures, but it’s still possible to remove it completely with surgery.
  • Stage 3: The tumor has spread beyond the kidney. It can be either because the tumor has burst before or during the operation and has spread to lymph glands (nodes) or has not been completely removed by surgery.
  • Stage 4: The tumor has spread to other parts of the body, such as the lungs or liver. Tumors in other parts of the body are known as metastases.
  • Stage 5: There are tumors in both kidneys (bilateral Wilms tumor).

If the tumor comes back after initial treatment, this is known as recurrent cancer or relapse.

Treatment for Wilms tumor

Specific treatment for Wilms tumor will be determined by the physician based on age, overall health, and medical history.

Treatment may include (alone or in combination):

  • Surgery to remove all or part of the affected kidney and any involved structures
  • Chemotherapy to shrink the remaining tumor or to treat metastasis or recurrent disease
  • Radiation to shrink the remaining tumor or to treat metastasis or recurrent disease
  • Medications to control pain, hypertension, nausea, and infections
  • Blood pressure monitoring
  • Continuous follow-up care to determine response to treatment, detect recurrent disease, evaluate the function of the remaining kidney, and manage late effects of treatment

Prompt medical attention and aggressive therapy are important for the best possible prognosis. Continued follow-up care is essential for the child diagnosed with a Wilms tumor. Side effects of chemotherapy and radiation, as well as second malignancies, can occur in survivors of cancer. New methods are continually being discovered to improve treatment and decrease side effects.

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Medically Reviewed on 12/18/2020
References
WebMD. Wilms Tumor. https://www.webmd.com/cancer/what-is-wilms-tumor#1