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Kidney Tumors

What are kidney tumors?

Graphic of a toddler with layover of organs with kidney highlighted and labeled

The kidneys are on either side of the spine in the back of the belly. Their main function is to filter and clean the blood and make urine.

Renal (kidney) tumors occur when cancer cells form in kidney tissues. These tumors account for about 7% of all childhood cancers.

There are different types of kidney tumors in children. Wilms tumor (nephroblastoma) is one type of childhood kidney tumor.

The kidneys are a pair of organs on either side of the spine in the back of the belly. They filter and clean the blood. The kidneys also make urine.

Wilms tumor is also known as nephroblastoma. It is the most common kidney cancer in children. About 500 children in the United States are diagnosed with Wilms tumor each year. It is most often found in children under age 5.

Renal cell carcinoma is the most common kidney tumor in teens between ages 15–19.

Other kidney tumors include:

  • Clear cell sarcoma of the kidney
  • Malignant rhabdoid tumor
  • Mesoblastic nephromas

Sometimes cancer may have spread before diagnosis. This depends on the type of tumor your child has. Wilms tumor, for example, rarely spreads to the brain.

Areas where cancer might spread can include:

  • Lungs
  • Liver
  • Bones
  • Lymph nodes

Treatment for most kidney tumors depends on the tumor. It may include:

The treatment and prognosis for kidney tumors depends on the type of tumor and whether it has spread to other organs. Your child’s doctor is the best source of information on your child’s case. 

Symptoms of kidney tumors

Common signs and symptoms of kidney tumors include:

  • Lump or swelling in the belly
  • Blood in the urine
  • Belly pain
  • High blood pressure
  • Fever
  • Loss of appetite
  • Weight loss
  • Constipation that does not go away with treatment
  • Fatigue
  • Confusion
  • Excessive thirst
  • Vomiting
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Risk factors for kidney tumors

Certain genetic syndromes or other conditions may increase risk for kidney tumor. But most kidney tumors are not genetic.

Genetic conditions that increase the risk include:

  • WAGR syndrome
  • Denys-Drash syndrome
  • Overgrowth syndromes (such as Beckwith-Wiedemann syndrome)

If your child’s care team thinks your child’s tumor might be caused by a genetic condition, they may suggest genetic testing.

Diagnosis of kidney tumors

Tests to diagnose kidney tumors include:

  • The patient’s medical history
  • A family health history to find out if the cancer has been passed down through your family.
  • A physical exam
  • Lab studies to look at blood and urine including:
    • Complete blood count
    • Liver and kidney tests to find out how the organs are working
    • Electrolyte tests to look at levels of sodium, chloride, magnesium, potassium, and calcium
    • Urinalysis to test the urine for sugar, protein, blood, and bacteria
  • Imaging of the belly to find out if a tumor is present, see how big it is, and find out if it has spread.
  • Examination of tissue that has been taken from the tumor. This will help doctors learn more about the type of cancer. This may be done through a biopsy or after surgical removal of the tumor.
Imaging tests such as the ultrasound help doctors understand the size of the tumor. Ultrasounds also show if the tumor has spread.

Imaging tests such as ultrasound help doctors understand the size of the tumor. Ultrasounds also show if the tumor has spread.

Stage of kidney tumors

Kidney tumors are classed based on the size of the tumor and whether the cancer has spread. Imaging tests, surgery, and pathology give information for the stage of disease. For all kidney tumor types:

  • Stage 1 and Stage 2 disease mean the cancer has not spread outside the kidney.
  • Stage 3 disease has spread outside the kidney. But the cancer is still inside the belly.
  • Stage 4 disease has spread outside the belly. It can be in the:
    • Chest
    • Lymph nodes
  • Stage 5 disease (for Wilms tumor only) means both kidneys are affected.

Patients whose cancer has spread to other parts of the body have a poorer prognosis. This is because the cancer is more serious. It is also harder to treat.

  1. Wilms tumor

    Wilms tumor

    Wilms tumor (WT), also called nephroblastoma, is the most common type of kidney cancer in children. There are about 500 new cases in the United States each year. About 75% of patients diagnosed with Wilms tumor are under age 5.

    Wilms tumor may affect one or both kidneys. Children with Wilms tumor are usually diagnosed around ages 2–3 if both kidneys are affected (bilateral) or ages 3–4 if one kidney is affected (unilateral).

    About 5–10% of patients have bilateral or multicentric (multiple tumors within the kidney) disease at diagnosis.

    Symptoms of Wilms tumor

    Common signs and symptoms of Wilms tumor include:

    • Lump or swelling in the belly
    • Blood in the urine
    • Belly pain
    • High blood pressure
    • Fever 
    • Loss of appetite
    • Weight loss
    • Constipation
    • Fatigue
    • Excessive thirst
    • Vomiting

    Some children may be treated for constipation for a few months before they are diagnosed with Wilms tumor.

    Risk factors for Wilms tumor

    In most cases, there is no clear cause for Wilms tumor.

    • It affects males and females equally.
    • Females are more likely to have it in both kidneys at diagnosis.
    • It is more common in Black children than White children.
    • It is less common in Asian populations.
    • About 10% of patients with Wilms tumor have hereditary conditions that increase risk. These include:
      • WAGR syndrome
      • Denys-Drash syndrome
      • Overgrowth syndromes (such as Beckwith-Wiedemann syndrome)

    Treatment of Wilms tumor

    If your child’s care team suspects your child has Wilms tumor, they will usually have surgery to remove the kidney.

    If only 1 kidney is affected, the entire kidney is often removed. People can live normal, healthy lives with only 1 kidney.

    If your child’s kidney tumor cannot be removed at diagnosis or if they have tumors in both kidneys, your child will receive chemotherapy before surgery.

    If your child has Wilms tumor in both kidneys, they may be able to have surgery to remove only part of each kidney. They will receive more chemotherapy after surgery.

    Treatment may also include radiation therapy, depending on your child’s condition.

    Eligible patients may think about taking part in a clinical trial.

    Prognosis for Wilms tumor

    In general, Wilms tumor is a curable disease. Five-year survival rates for Wilms tumor patients with less aggressive histology are above 90% in the United States.

    Prognosis depends on:

    • Age at diagnosis. Patients diagnosed before age 10 usually have a better prognosis.
    • Stage of cancer at diagnosis
    • Pathology (how the cells look under a microscope) and/or molecular features of the tumor. The cells are identified as favorable or unfavorable.
      • Unfavorable histology (also known as anaplasia) means there are more cancer cells that divide rapidly and look very different than normal cells. These cells are harder to treat and are linked to lower survival rates. They can be in one area (focal) or spread throughout the tumor (diffuse).
    • Genetic factors and molecular markers of the tumor
    • Whether the cancer has come back

    Your child’s doctor is the best source of information on your child’s case. 

  2. Renal cell carcinoma

    Renal cell carcinoma

    Renal cell carcinoma (RCC) is rare in children. Kidney tumors overall account for about 7% of childhood cancers. RCC accounts for only 5% of those kidney tumors.

    RCC is more common in teens ages 15–19. It is the most common kidney cancer among adults. Subtypes of RCC include:

    • Translocation type
    • Clear-cell
    • Papillary
    • Unclassified

    Children with RCC are often diagnosed with more advanced cancer than adults. But children tend to have better outcomes. This is true even if the cancer has spread to nearby lymph nodes.

    If cancer has spread outside the kidney and lymph nodes to areas such as the lungs or liver, then prognosis is poor.

    Symptoms of renal cell carcinoma

    Common signs and symptoms of RCC include:

    • Lump or swelling in the belly
    • Blood in the urine
    • Belly pain

    Other symptoms may include:

    • High blood pressure
    • Fever
    • Loss of appetite
    • Weight loss
    • Constipation

    Risk factors for renal cell carcinoma

    Some inherited conditions put children at higher risk for renal cell carcinoma. These include:

    • Von Hippel-Lindau disease
    • Tuberous sclerosis
    • Hereditary leiomyomatosis and renal cell carcinoma syndrome (HLRCC)
    • Other gene changes passed down in families

    Renal medullary carcinoma is a rare type of renal cell carcinoma that may be linked to sickle cell disease.

    Previous treatment for childhood cancers with radiation or chemotherapy is a risk factor for kidney tumors, specifically renal cell carcinoma.

    Treatment of renal cell carcinoma

    Surgery to remove the kidney and affected lymph nodes is the main treatment for renal cell carcinoma.

    RCC does not respond well to radiation or chemotherapy. There is no standard chemotherapy or radiation therapy used for this cancer.

    Small tumors may be treated with ablation to freeze or burn the cancer cells.

    Immunotherapy may be used for people with advanced RCC or any RCC with a targetable lesion that cannot be completely removed.

    Certain targeted therapies have also been used in adults with advanced RCC but have not been studied widely in children.

    Eligible patients may think about taking part in a clinical trial.

    Prognosis for renal cell carcinoma

    The chance of cure for patients with renal cell carcinoma depends on:

    • Stage of the cancer at diagnosis:
      • Stage 1: 90%
      • Stage 2: 80%
      • Stage 3: 70%
      • Stage 4: 15%
    • Whether surgery can completely remove the tumor
    • Whether the cancer is recurrent (has come back)

    Your child’s doctor is the best source of information about your child’s case.

  3. Other kidney tumors

    Rare childhood kidney tumors include:

    • Malignant rhabdoid tumor
    • Clear cell sarcoma of the kidney
    • Mesoblastic nephromas

    Malignant rhabdoid tumor of the kidney

    A malignant rhabdoid tumor (MRT) most often occurs in young children and infants. These tumors are often not diagnosed until the disease is more advanced.

    A rhabdoid tumor of the kidney can spread to the brain and lungs.

    Occasionally, a rhabdoid tumor of the kidney will occur at the same time as a brain tumor called an atypical teratoid rhabdoid tumor.

    Rhabdoid tumors have a common gene change. Genetic testing might be an option for your family after diagnosis.

    Children may have this mutation in every cell in their body.

    If your child has a rhabdoid tumor, you may meet with a genetic counselor and discuss testing both tumor and healthy cells for gene mutations that can cause these tumors to develop.

    An MRT requires surgery. Chemotherapy medicines can be used. Radiation may also be used in some cases. But surgery is the main treatment. Researchers are looking at other options through clinical trials.

    Older patients with rhabdoid tumors tend to have a better chance of recovery. The overall survival rate for children with MRT is less than 50% in the United States. Children with disease that has spread through the body have a poor long-term outlook.

    Your child’s doctor is the best source of information about your child’s case. 

    Clear cell sarcoma of the kidney

    Clear cell sarcoma of the kidney (CCSK) is quite rare. It makes up less than 3% of pediatric kidney tumors. Only about 20 children are diagnosed with clear cell sarcoma in the United States each year.

    It is most often found in children ages 1–4 years. It occurs more often in boys.

    Compared to other kidney tumors, CCSK is more likely to spread to bone. But less than 5% of patients have cancer that has spread when they are diagnosed.

    Common sites for spread of disease include:

    • Lung
    • Bone
    • Brain
    • Soft tissue

    Treatment of CCSK includes surgery to remove the kidney. Treatment can also include chemotherapy and radiation after surgery. In the future, other treatment options such as targeted therapies may be an option.

    Children treated for CCSK are at risk for the tumor to return later in life. The most common sites for recurrence are the brain and lungs.

    Younger age and greater extent of disease at diagnosis are linked to less favorable outcomes. Your child’s doctor is the best source of information about your child’s case.

    Mesoblastic nephroma or congenital mesoblastic nephroma

    Mesoblastic nephroma occurs most often in newborns and infants. The main symptom is a lump or mass in the belly.

    About 90% of patients are diagnosed before age 1. It is more common in boys. Sometimes a diagnosis is made before birth through prenatal ultrasound.

    Younger age (less than 3 months) is linked to better outcomes for patients with mesoblastic nephroma.

    There are 2 major types of mesoblastic nephroma:

    • Classic mesoblastic nephroma: Diagnosed before birth or before 3 months of age.
    • Cellular mesoblastic nephroma: Linked to genetic translocation. It has a greater risk of recurrence.

    Surgery to remove the kidney is the main treatment. In some cases, chemotherapy may also be used. 

    Targeted therapies for tumors with genetic factors are being studied in clinical trials.

    The survival rate for mesoblastic nephroma is greater than 95% in the United States. Your child’s doctor is the best source of information about your child’s case. 

Support for patients after kidney cancer

Monitoring for recurrence

Patients will get follow-up care to screen for recurrence after treatment. Your child’s care team will suggest the tests your child needs.

If your child has a syndrome or genetic difference that is passed through families, they may need genetic testing and extra care.

Life after nephrectomy

Patients who have had a kidney removed can lead normal, active lives.

It is important to talk about medical needs and lifestyle habits with your child’s care team.

Your child will need regular medical care with a check-up at least yearly. Tests might include:

  • Blood pressure
  • Kidney function (BUN, creatine)
  • Urinalysis

Your child may need to see a kidney specialist called a nephrologist.

Ways to protect kidney health

  • Drink about 6–8 cups of water per day. Stay hydrated when playing sports and in hot weather.
  • Limit caffeine.
  • Be careful with the use of non-steroidal anti-inflammatory drugs (NSAIDs). These medicines can harm the kidneys when used too often or taken in too high of a dose. Avoid these medicines when possible. Talk with the care team before your child takes them.
  • Check with a doctor or pharmacist before taking a new medicine. This includes prescription and over-the-counter medications as well as herbal supplements. Make sure all health care providers and pharmacists know your child has only one kidney.
  • Avoid constipation by staying hydrated and eating fiber. Take medicines to soften stool if your child’s care team suggests them.
  • Make sure your child is ready before potty training to avoid issues with holding urine.
  • Call the doctor at any sign of urinary tract infection (UTI) or kidney infection.
  • Be physically active. Most physical activities and sports (including contact sports) pose little to no risk to kidney health. Talk to your child’s care team about activities and any concerns.

Late effects

Children treated for kidney tumors are at risk for late effects related to therapy.

Living a healthy lifestyle, eating a healthy diet, and having regular screenings and checkups can help protect your child’s health.

Survivors treated with systemic chemotherapy or radiation should be monitored for acute and late effects of therapy. Depending on the type of treatment given, these effects can include:

Your child’s doctor is the best source of information about your child’s case.

Questions to ask your care team

  • What are our treatment options?
  • Will my child have limitations after surgery?
  • What are the possible side effects of each treatment?
  • What can be done to manage side effects?
  • Will my child need to be in the hospital for treatment?
  • Where is the treatment available? Is it close to home or will we have to travel?

Key points about kidney tumors

  • Kidney tumors occur when cancer cells form in kidney tissues.
  • Your child’s care team will use a variety of tests including imaging tests to diagnose a kidney tumor.
  • Surgery is one of the most common treatments for kidney tumors.
  • It is possible to live a full, active life with 1 kidney.
  • Your child will need to be monitored for recurrence and late effects after treatment.

Related Factsheets

—
Reviewed: August 2024

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