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Kidney Tumors

What are Kidney Tumors?

Renal (kidney) tumors occur when cancer cells form in the tissues of the kidney. There are different types of renal tumors in children. Together, they account for about 7% of all childhood cancers. Common types of pediatric kidney tumors include Wilms tumor (nephroblastoma) and renal cell carcinoma.

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

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

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

Wilms tumor, also known as nephroblastoma, is the most common kidney cancer in children. About 500 children are diagnosed with Wilms tumor each year in the United States. It is most often found in children under 5 years of age. Among teens ages 15-19, the most common kidney tumor is renal cell carcinoma. Other kidney tumors include clear cell sarcoma of the kidney, malignant rhabdoid tumor, and mesoblastic nephromas. Other cancers such as sarcomas can occur in the kidney but may also arise in other parts of the body.

Common signs and symptoms of renal tumors include a lump, swelling or pain in the abdomen, blood in the urine, high blood pressure, fever, constipation, weight loss, or loss of appetite. Having certain genetic syndromes or other conditions may increase risk for developing a renal tumor.

Depending on the type of tumor, cancer may be found in one or both kidneys. Sometimes cancer may have spread to the lungs, liver, bones, brain, or lymph nodes at diagnosis.

Treatment for most renal tumors depends on the tumor and may include a combination of surgery, chemotherapy, and/or radiation therapy. Nephrectomy is surgery to remove all (radical nephrectomy) or part (partial nephrectomy) of the kidney. The type of renal tumor and extent of disease affects the prognosis and treatment options.

Signs and Symptoms of Kidney Tumors

Common signs and symptoms of kidney tumors include:

  • Lump or swelling in the abdomen
  • Blood in the urine
  • Abdominal pain
  • High blood pressure
  • Fever
  • Loss of appetite
  • Weight loss
  • Constipation

Patients may have fatigue, confusion, excessive thirst, and/or vomiting due to high levels of calcium in their blood (hypercalcemia). Some patients may be treated for constipation without relief of symptoms due to the underlying abdominal mass.

Diagnosis of Kidney Tumors

Several types of tests are used to diagnose and evaluate kidney tumors. These tests include:

  • A health history and physical exam to learn about symptoms, general health, past illnesses, and risk factors. Family history is important to determine whether the cancer is hereditary or non-hereditary. Certain inherited conditions can increase risk for some cancers.
  • Lab studies to look at blood and urine including:
    • Complete blood count to check the blood for the number of red blood cells, white blood cells, and platelets; the amount of hemoglobin in the red blood cells; and the portion of the blood made up of red blood cells.
    • Liver and kidney function tests to evaluate 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 tests of the abdomen to confirm the presence of a mass, see how big the tumor is, and determine if it has spread.
    • X-ray uses electromagnetic energy to take 2-dimensional pictures of different areas of the body such as the chest and abdomen.
    • Ultrasound or ultrasonography uses sound waves to create an image of the kidney.
    • Computed tomography (CT scan) uses a series of X-rays to create 3-dimensional images of the organs and tissues inside the body. Dye may be injected into a vein to help organs be viewed more clearly.
    • Magnetic resonance imaging (MRI) makes detailed 3-dimensional pictures of the abdomen using radio waves and magnets.
    • To determine if cancer has spread outside the kidney, additional imaging tests may be performed to examine the chest, brain, and bones.
  • Examination of tissue from the tumor to learn more about the histology of the cells and 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 the ultrasound help doctors understand the size of the tumor. Ultrasounds also show if the tumor has spread.

Staging of Kidney Tumors

The stage of cancer indicates the size of the tumor and if the cancer has spread. Imaging tests, surgery, and pathology examination give information for the stage of disease. For all kidney tumor types:

  • Stage I and Stage II indicate localized disease that has not spread outside the kidney. 
  • Stage III disease has spread outside the kidney, but the cancer remains inside the abdomen. 
  • Stage IV disease has spread outside the abdomen to the chest, bones, brain, liver or other lymph nodes. 
  • Stage V disease (for Wilms tumor only) means both kidneys are affected.

For all renal tumors, patients with advanced stage disease (cancer has spread or metastasized to other parts of the body) have a poorer prognosis because the illness is more serious and harder to treat.

Life after Kidney Cancer

Monitoring for recurrence

Patients will receive follow-up care to screen for recurrence for a period of time after treatment. The medical team will make specific recommendations for frequency and types of tests needed. Patients with certain inherited syndromes or genetic conditions may be at risk for future cancers and need additional care.

Life after nephrectomy

Patients who have had a kidney removed can lead normal, active lives with one kidney. However, it is important that families discuss medical needs and lifestyle habits with their doctor. Patients should have regular medical care with a check-up at least yearly. Tests should include blood pressure, kidney function (BUN, creatine), and urinalysis. If there are problems, patients should be followed by a nephrologist.

Ways to protect kidney health

  • Drink enough water, about 6-8 cups per day, and avoid dehydration. Be especially careful to stay hydrated when playing sports and in hot weather.
  • Limit caffeine intake.
  • Be careful with the use of non-steroidal anti-flammatory drugs ( NSAIDs), as the overuse of these medicines can harm the kidneys when taken in too high of a dose or used too often. Avoid these medicines when possible, and discuss with a doctor before taking.
  • 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 that all health care providers and pharmacists know if a patient has only one kidney.
  • Avoid constipation by staying hydrated and eating fiber. Take medications to soften stool if they are recommended by a doctor.
  • Make sure children are ready before beginning 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 a health care provider about activities and any concerns.

Late effects

Children who receive treatment for kidney tumors are at risk for late effects related to therapy. For general health and disease prevention, all cancer survivors should adopt healthy lifestyle and eating habits, as well as continue to have regular physical checkups and screenings by a primary physician. Survivors treated with systemic chemotherapy or radiation should be monitored for acute and late effects of therapy. Serious chronic health conditions are present 25 years after diagnosis in approximately 25% of survivors, according to the Childhood Cancer Survivor Study. These conditions include second cancers (increased risk following exposure to radiation and certain chemotherapy drugs), congestive heart failure (exposure to doxorubicin), infertility or complications during pregnancy (increased risk following exposure to multiple different chemotherapy agents), and end-stage kidney disease or kidney failure. Survivors who had a nephrectomy are at higher risk for kidney problems.


Reviewed: June 2018