Wilms Tumor Facts

Wilms Tumor Facts

Wilms Tumor

Wilms tumor, also called as nephroblastoma, is a type of cancerous tumor in the kidneys. The name of the disease comes from a German doctor named Max Wilms, who wrote about it in 1899. Children ages 3-4 years old are more likely to develop Wilms tumor.

Wilms tumor accounts for around 9 out of 10 kidney cancers in children. Most cases of Wilms tumors only affect one kidney (unilateral). Around 5-10 percent of children diagnosed with Wilms tumor have more than one tumor in one kidney. Moreover, tumors in both kidneys (bilateral) occur in approximately 5 percent of children with the disease. These tumors may become very large before they are detected. However, most of them are found before they metastasize to other organs in the body. 

Facts About Wilms Tumor

1. Wilms tumor is a type of malignant kidney tumor in children.

Both kidneys can be affected by Wilms tumor, although the disease often affects just one. Experts believe that the tumor starts to grow when a fetus is still developing in the womb, and that some cells in the kidney tend to malfunction and form into a tumor.

Wilms tumor may also metastasize to children’s liver, lungs, and nearby lymph nodes.

2. Children with certain birth defects or genetic disorders may have an increased risk of developing the disease.

Below are birth defects and genetic disorders that have been linked to Wilms tumor:

  • Hypospadias (a birth defect in the male reproductive system)
  • Cryptorchidism (refers to an undescended testis)
  • Denys-Drash syndrome or DDS (a disorder that affects the genitalia and kidneys)
  • Beckwith-Wiedemann syndrome (an overgrowth disorder)
  • WAGR syndrome or WAGR complex (a genetic disorder characterized by Wilms tumor, aniridia or absence of the iris, genitourinary anomalies, and intellectual disability or mental retardation)
  • Idiopathic hemihypertrophy (a congenital overgrowth disorder)

Children with the said conditions should undergo quarterly screening until they reach their 8th birthday. Speak with a doctor if you think that your child may have a risk of developing the disease.

3. Wilms tumor accounts for around five percent of all cancers in children.

Approximately 500 cases of Wilms tumor are annually reported in the United States alone. Moreover, this statistic has remained steady for a number of years. On an average, most children diagnosed with Wilms tumor are usually 3-4 years old. The risk of developing the disease reduces when children grow older.

Wilms tumor is usually uncommon in children who are 6 years old and above. Although it rarely happens, there are also cases wherein adults develop the disease. 

4. An abdominal lump and the presence of blood in the urine are possible signs of Wilms tumor and other types of childhood kidney tumors.

Below are the signs and symptoms that may indicate kidney problems. Immediately consult a doctor if you notice any of the following symptoms in your child:

5. Wilms tumor is described according to histology. 

The prognosis and the treatment of Wilms tumor usually depend on its histology, which can either be unfavorable (anaplastic) or favorable. Response to chemotherapy and prognosis are better if the tumor is favorable. However, chemotherapy treatment is harder when it comes to rapidly dividing anaplastic tumor cells. 

6. The prognosis and treatment options of Wilms tumor are affected by certain factors. 

The outlook of a child with Wilms tumor depends on the following factors:

  • Stage of cancer 
  • Type of cancer cells 
  • The patient's age and general health at the time of diagnosis 
  • Size of the primary tumor
  • The patient's response to therapy
  • The patient's tolerance to medications, procedures, or therapies

7. Wilms tumor and other kidney tumors are often diagnosed and treated with surgery. 

Surgery is usually done to determine whether tumors are cancerous or not. The surgeon will remove the whole kidney if the tumor is within the kidney. A piece of the tumor will be removed if the tumor is present in both kidneys or has spread. This sample is sent to the laboratory and further examined under the microscope.

8. Some cancer treatments for Wilms tumor and other types of childhood kidney tumors cause side effects months or years after the treatment has ended.  

Some of the side effects during or after cancer treatments include:

  • Physical problems
  • Changes in thinking, mood, and feeling
  • New types of cancer

Some of these side effects can be controlled or treated. Clinical trials are ongoing to determine whether lower doses of chemotherapy and radiation are effective.


The following are tests and procedures to help identify Wilms tumor and other types of childhood kidney tumors:

  • Medical History and Physical Examination: Involves taking a patient’s history regarding past diseases and treatments along with checking for any signs of illness and evaluating overall health status.  
  • Complete Blood Count (CBC): A CBC is a blood test used to obtain information about a patient’s blood, such as blood cell counts for each cell type. This test usually helps healthcare providers to have an overview of their patient’s current health status.
  • Blood Chemistry Tests: These are a group of tests that involve the measurement of different substances in the blood, which are released by tissues or those that are produced during the metabolism of certain substances.
  • Liver Function Test: This a group of blood tests performed to obtain more information about the status of a patient’s liver.
  • Renal Function Test: This test is also called as kidney function test. It is used to evaluate the overall functioning of a patient’s kidneys.
  • Urinalysis:  This is a urine test, which involves chemical, physical, and microscopic tests. It is usually used to measure or detect different substances that are present in the urine, such as cells, bacteria, and byproducts of both abnormal and normal metabolisms.
  • Ultrasound Scan: Also known as sonography, an ultrasound scan is an imaging test that uses sound waves to help visualize live images inside the body. When a kidney tumor is suspected, an abdominal ultrasound is usually done.
  • CT Scan: A computed tomography scan or CT scan is a type of imaging scan that uses X-rays paired with a computer to produce more detailed internal images of the body.  
  • Biopsy: It is a procedure wherein a sample of cells or a piece of tissue is removed from the body for further laboratory analysis. A biopsy is usually done to check for any signs of cancer. It can be done before having any treatment, after undergoing surgery for tumor removal, or after chemotherapy. 


The four standard treatments used for Wilms tumor are:

  • Surgery
  • Chemotherapy or combination chemotherapy
  • Radiation therapy
  • Biologic therapy

Treatment should be planned by a team of healthcare providers, particularly those who have expertise in children's cancer treatment. A pediatric oncologist will oversee the treatment of children with Wilms tumor. Pediatric oncologists often work with other pediatric healthcare providers, who specialize in certain areas of medicine. They include:

  • Radiation oncologist
  • Pediatric surgeon or urologist
  • Pediatric nurse specialist
  • Rehabilitation specialist
  • Social worker