What Is the Most Common Primary Tumor of the Kidney in Children?

Medically Reviewed on 5/11/2022
What is the most common primary Tumor of the kidney in children?
Wilms tumor accounts for about five percent of all childhood malignancies.

Wilms tumor, also known as nephroblastoma, is the most common primary tumor of the kidney in children. It is often seen in children aged three to four years old and becomes less common as they grow older. It is very rare in adults.

Most often, Wilms tumor affects only one kidney; however, involvement of both kidneys is also seen.

In the United States, 500 to 600 new instances of Wilms tumor are diagnosed each year. It accounts for about five percent of all childhood malignancies. Advances in the identification and timely adequate treatment of Wilms tumor have substantially increased the prognosis for children with this condition.

What are the symptoms of Wilms tumor?

Symptoms of Wilms tumor differ from child to child, meaning there are no symptoms that are specific for it. However, most children with these tumors may experience the following symptoms:

Other common symptoms include:

In most cases, the child appears normal and healthy without any obvious symptoms. However, changes in the size of the abdomen or detection of a lump or mass in the child’s abdomen can alert parents to the development of a tumor.

What are the causes of and risk factors for Wilms tumor?

It's unclear what causes Wilms tumor, but genes may play a role in rare cases. In most cases, there is no recognized link between parents and children that might result in cancer. However, in rare situations, faulty DNA that causes Wilms tumor is handed down from parent to kid.

Two risk factors include:

  1. Ethnicity: Children of African American descent have a slightly higher risk of Wilms tumor than those of other ethnicities. Children of Asian American descent tend to be at a lesser risk than those of other ethnicities.
  2. Family history: The risk of a Wilms tumor in a child increases if any one of the family members has it.

Other syndromes associated with Wilms tumor include:

  • Aniridia: Part or complete absence of iris of the eye
  • Hemihypertrophy: Body parts on one side of the body are larger than on the other side
  • WAGR syndrome: Presence of all of the following
    • Wilms tumor
    • Aniridia
    • Genital and urinary abnormalities 
    • Intellectual disabilities
  • Beckwith-Wiedemann syndrome: Children are often bigger than the usual (macrosomia). Other symptoms may include
    • Protrusion of abdominal organs into the umbilical cord's base 
    • Macroglossia (large tongue)
    • Larger internal organs
    • Ear issues
    • Increased risk of malignancies
  • Denys-Drash syndrome: Wilms tumor associated with kidney issues and male pseudohermaphroditism (men born with testicles display feminine features)

How is Wilms tumor diagnosed?

The doctor may perform a thorough medical history and physical examination of your child and may request tests to detect the presence and further analysis of the tumor. These tests identify if cancer has spread to other parts of the body (metastasis).

Radiological imaging

  • Abdominal ultrasound: It is a radiological imaging technique that uses high-frequency sound waves to provide images of internal organs, blood arteries, and tissues. The location and size of the tumor can be identified with an abdominal ultrasound.
  • Chest X-ray: X-rays are used to produce images of the heart, lungs, and ribcage. Any abnormalities in these structures can be seen in an X-ray image.
  • Computerized tomography (CT) of the abdomen: X-rays and computer technology are used to create comprehensive cross-sectional pictures (slices) of the body, including the bones, muscles, fat, and organs. They can reveal the presence of a tumor in the kidneys and if cancer has migrated to other organs such as the liver, another kidney, or lymph nodes.
  • Magnetic resonance imaging (MRI): An MRI scan uses radio waves, powerful magnets, and computer technologies. An MRI provides more comprehensive pictures than CT and ultrasound and can help physicians determine whether cancer has spread to one of the major blood veins surrounding the kidney.

Laboratory tests

  • Blood tests: Various blood tests and urine tests are performed to identify the markers that give the picture of kidney and liver functions and general health.
  • Biopsy: The majority of children will undergo a biopsy, in which a sample of tissue from the tumor is removed and analyzed under a microscope, which aids in the diagnosis and treatment plan.

Staging of Wilms tumor

Staging and categorizing the illness is an important element of diagnosing Wilms tumor. It aids the doctor in determining treatment choices and prognosis for your child. Wilms tumor staging refers to the process of assessing whether cancer has spread and, if so, how far it has progressed. Doctors classify kidney tumors into five stages.

According to the Children's Oncology Group, a nationwide collaboration of pediatric cancer hospitals, Wilms tumor is staged as follows:

  1. Stage I:
    • The tumor affects only one kidney, and there is no spreading of cancer outside the renal capsule, indicating that there is no vascular invasion.
    • Surgery is done to remove the tumor completely.
    • This is the most common stage of Wilms tumor, accounting for 40 to 45 percent of all Wilms tumors.
  2. Stage II:
    • The tumor is restricted to the kidney, but it affects the capsule surrounding the kidney and the kidney's collecting system. 
    • Because the tumor is localized to the kidney, complete removal of the tumor surgically is possible. 
    • This stage accounts for 20 percent of Wilms tumors.
  3. Stage III:
    • The tumor has spread outside the kidney.
    • Cancer cells may be seen in the resection margins and any of the other adjacent parts such as:
      • Regional lymph nodes surrounding the kidney
      • Along the aorta
      • Inferior vena cava
    • The spread of cancer cells from the mass following biopsy or rupture of the tumor comes under stage III.
  4. Stage IV:
    • The tumor is progressed to organs such as the lungs, liver, brain, or bones through the bloodstream.
    • Stage IV accounts for approximately 10 to 15 percent of all Wilms tumors.
  5. Stage V:
    • Both the kidneys are noted to have tumors at the time of the initial diagnosis.
    • About 5 to 10 percent of cases of all Wilms tumors are stage V.

4 treatment options for Wilms tumor

The doctor determines the appropriate treatment option for Wilms tumor based on the following factors:

  • Age, general health, and medical history of your child
  • Tumor type, location, and size
  • Disease's severity (stage)
  • Tolerance of your child to certain drugs, surgeries, or therapies
  • Anticipation of prognosis by the doctor
  • Tumor genetic traits

Various treatments include:

  1. Surgery: Unilateral nephrectomy, surgical removal of the afflicted kidney, and regional lymph node biopsy are the most common treatment options for Wilms tumor. Children with stages I and II Wilms tumors are often treated with surgery. Chemotherapy is usually suggested before surgery, and in certain cases, radiation treatment may be given following surgery. However, in some situations of low-stage Wilms tumor, surgery alone can be used to treat it.
    • The following surgical procedures are used to remove Wilms tumor:
      • Radical nephrectomy: Radical nephrectomy is the complete removal of the kidney, along with other parts such as
        • The tissue surrounding the kidney
        • Ureter (the tube that drains urine from the kidneys to the bladder)
        • Adrenal gland (the small gland that is present in the kidney)
        • This procedure is done only if the tumor is confined to one kidney.
      • Partial nephrectomy: This is usually known as kidney sparing surgery. The surgeon will remove the tumor while preserving as much healthy kidney tissue as possible.
  2. Chemotherapy: If the tumor is particularly big, the doctor may consider chemotherapy before surgery to try to decrease the tumor. Vincristine, doxorubicin, dactinomycin, carboplatin, cyclophosphamide, and etoposide are commonly used chemotherapy drugs for Wilms tumors. Chemotherapy may be given following surgical removal of the tumor.
  3. Radiation therapy: The requirement for radiation is determined by the stage (the extent to which the tumor has spread) and type of the tumor. Radiation treatment may be used to treat malignancies that have spread to the lymph nodes, abdomen, or lungs.
  4. Stem cell transplant: In rare situations, your doctor may advise you to have a stem cell transplant to treat your malignancy. Stem cell transplant helps with the administration of high-intensity chemotherapy for Wilms tumors that are difficult to treat. Stem cell transplantation and the therapy required to manage its consequences are both difficult and risky.

With the introduction of new medicines such as chemotherapy, the five-year survival rate for Wilms tumor in the United States is 92 percent. Follow-up medical care and supportive treatment will be given to your child following surgery or any other treatment for tumors. Yearly follow-up medical evaluation is done, along with genetic counseling, patient and family education, psychological assessment, and other supportive services.

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8 complications that require long-term evaluation followed by the treatment for Wilms tumor

Even after successful treatment of Wilms tumor, some children are at a higher risk of other medical issues in the future. This is because chemotherapy and radiation therapy can destroy the healthy tissues of the body.

As a result, children who have had Wilms tumor therapy must be continuously followed for any long-term or late complications of the treatment, such as:

  1. Kidney failure
    • Following treatment, most children end up with a single kidney, and the risk of kidney failure is high.
    • It is essential to protect the kidney by following healthy lifestyles, being well hydrated, and avoiding drugs that affect the kidneys such as ibuprofen and codeine.
    • Continued monitoring of the kidney is followed for the rest of the life.
  2. Heart problems:
    • Children who receive chemotherapy drug doxorubicin and who underwent radiation therapy are at a higher risk of heart abnormalities.
    • An echocardiogram is done to detect any possible heart abnormalities.
  3. Lung issues:
    • Radiation therapy done for lung metastasis increases the risk of various lung issues following treatment.
    • Pulmonary function tests are to be done to assess the functionality of the lungs.
  4. Bowel obstruction:
    • Following surgery, scar tissue may be formed that causes bowel obstruction.
    • Abdominal pain and vomiting are common symptoms associated with bowel obstruction.
  5. Skeletal abnormalities:
    • Children who have had radiation therapy may develop scoliosis, spine curvature issues, and underdevelopment of adjacent soft tissue.
    • This risk is determined by the location and dose of radiation treatment.
  6. Secondary cancer:
    • Wilms tumor survivors had a low probability of having another type of cancer within 15 years following diagnosis and treatment of Wilms tumor.
    • The development of secondary cancer depends on whether radiation therapy and doxorubicin are used during treatment.
    • Young girls who receive radiation therapy to treat Wilms tumor that has migrated to the lungs will have an increased risk of breast cancer.
  7. Dental issues:
    • Depending on the age of the child and diagnosis and treatment of Wilms tumor, dental abnormalities such as tooth development disorders, enamel concerns, or missing teeth may be seen. 
    • Regular dental care is crucial.
  8. Fertility and pregnancy issues in women:

5 tips to care for a child following diagnosis and treatment of Wilms tumor

Five tips to care for a child following diagnosis and treatment of Wilms tumor include:

  1. The term “survivorship” can imply different things to different individuals although it frequently refers to living with, through, and after cancer.
  2. Most treated children will not be unable to accomplish many activities.
  3. Most children who are being treated for Wilms tumor do not have any unique dietary requirements.
  4. Children who have had cancer can improve their future by adapting to healthy principles into and through adulthood, such as not smoking, maintaining a healthy weight, eating healthily, managing stress, and engaging in regular physical activity. 
  5. Consult with your doctor about building a plan that is appropriate for your child's needs.

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Medically Reviewed on 5/11/2022
References
Image Source: iStock Image

Wilms Tumor: https://www.webmd.com/cancer/what-is-wilms-tumor

Wilms Tumor: https://kidshealth.org/en/parents/wilms.html

Wilms Tumor - Childhood: Symptoms and Signs: https://www.cancer.net/cancer-types/wilms-tumor-childhood/symptoms-and-signs

What is Kidney Cancer in Children? https://www.urologyhealth.org/urology-a-z/k/kidney-cancer-in-children