- Risk Factors
- Signs & Symptoms
Wilms tumor and other childhood kidney tumors are diseases in which malignant (cancer) cells form in the tissues of the kidney.
Wilms tumor and other kidney tumors are diseases in which malignant (cancer) cells are found in the kidney. In Wilms tumor, one or more tumors may be found in one or both kidneys. There are two kidneys, one on each side of the backbone, above the waist. Tiny tubules in the kidneys filter and clean the blood, taking out waste products and making urine. The urine passes from each kidney through a long tube called a ureter into the bladder. The bladder holds the urine until it is passed from the body. Wilms tumor may spread to the lungs, liver, or nearby lymph nodes. Diffuse hyperplastic perilobar nephroblastomatosis (DHPLN) is a condition in which abnormal tissue grows on the outer part of one or both kidneys. Children with DHPLN are at risk for developing a type of Wilms tumor that grows quickly. Frequent follow-up testing is important for at least 7 years after the child is diagnosed with DHPLN.
Other kidney tumors
Clear cell sarcoma of the kidney, rhabdoid tumor of the kidney, neuroepithelial tumor of the kidney, renal cell cancer (RCC), and mesoblastic nephroma are also childhood kidney tumors, but they are not related to Wilms tumor.
- Clear cell sarcoma of the kidney is a type of kidney tumor that may spread to the lung, bone, brain, and soft tissue.
- Rhabdoid tumor of the kidney is a type of cancer that occurs mostly in children under age 2. It grows and spreads quickly, often to the lungs and brain.
- Neuroepithelial tumors of the kidney are rare and usually occur in young adults. They grow and spread quickly.
- Renal cell carcinoma occurs rarely in children. The tumor can spread to the lungs, bones, liver, and lymph nodes.
- Mesoblastic nephroma is a tumor of the kidney that is usually diagnosed within the first 3 months of life. It may also be found during an ultrasound before birth. Mesoblastic nephroma occurs more often in males than females.
Having certain genetic syndromes or birth defects can increase the risk of developing Wilms tumor.
Anything that increases your risk of getting a disease is called a risk factor. Wilms tumor may be part of a genetic syndrome that affects growth or development. A genetic syndrome is a set of symptoms or conditions that occur together and is usually caused by abnormal genes. Certain birth defects can also increase a child's risk for developing Wilms tumor. The following genetic syndromes and birth defects have been linked to Wilms tumor:
- WAGR (Wilms tumor, aniridia, ambiguous genitalia, and mental retardation) syndrome.
- Beckwith-Wiedemann syndrome.
- Denys-Drash syndrome.
Children with these genetic syndromes and birth defects should be screened for Wilms tumor every three months until age 8. An ultrasound test may be used for screening.
Having certain conditions may be associated with renal cell carcinoma.
Renal cell carcinoma may be related to the following conditions:
- Von Hippel-Lindau disease (an inherited condition that causes abnormal growth of blood vessels).
- Tuberous sclerosis (an inherited disease marked by noncancerous fatty cysts in the kidney).
- Neuroblastoma and/ or sickle cell disease.
Possible signs of Wilms tumor and other childhood kidney tumors include a lump in the abdomen and blood in the urine.
These and other symptoms may be caused by kidney tumors. Other conditions may cause the same symptoms. A doctor should be consulted if any of the following problems occur in the child:
- A lump, swelling, or pain in the abdomen.
- Blood in the urine.
- Fever for no known reason.
Tests that examine the kidney and the blood are used to detect (find) Wilms tumor and other childhood kidney tumors.
The following tests and procedures may be used:
- Physical exam and history: An exam of the body to check general signs of health, including checking for signs of disease, such as lumps or anything else that seems unusual. A history of the patient's health habits and past illnesses and treatments will also be taken.
count (CBC): A procedure in which a sample of blood is drawn and
checked for the following:
- The number of red blood cells, white blood cells, and platelets.
- The amount of hemoglobin (the protein that carries oxygen) in the red blood cells.
- The portion of the blood sample made up of red blood cells.
- Blood chemistry studies: A procedure in which a blood sample is checked to measure the amounts of certain substances released into the blood by organs and tissues in the body. An unusual (higher or lower than normal) amount of a substance can be a sign of disease in the organ or tissue that makes it.
- Liver function test: A procedure in which a blood sample is checked to measure the amounts of certain substances released into the blood by the liver. A higher than normal amount of a substance can be a sign that the liver is not working as it should.
- Renal function test: A procedure in which blood or urine samples are checked to measure the amounts of certain substances released into the blood or urine by the kidneys. A higher or lower than normal amount of a substance can be a sign that the kidneys are not working as they should.
- Urinalysis: A test to check the color of urine and its contents, such as sugar, protein, blood, and bacteria.
- Ultrasound exam: A procedure in which high-energy sound waves (ultrasound) are bounced off internal tissues or organs and make echoes. The echoes form a picture of body tissues called a sonogram. An ultrasound of the abdomen is done to diagnose a kidney tumor.
- CT scan (CAT scan): A procedure that makes a series of detailed pictures of areas inside the body, taken from different angles. The pictures are made by a computer linked to an x-ray machine. A dye may be injected into a vein or swallowed to help the organs or tissues show up more clearly. This procedure is also called computed tomography, computerized tomography, or computerized axial tomography.
- Abdominal x-ray: An x-ray of the organs inside the abdomen. An x-ray is a type of energy beam that can go through the body and onto film, making a picture of areas inside the body.
- Biopsy: The removal of cells or tissues so they can be viewed under a microscope by a pathologist to check for signs of cancer.
Wilms tumor and other childhood kidney tumors are usually diagnosed and removed in surgery.
Once a kidney tumor is found, surgery is done to find out whether or not the tumor is cancer. If the tumor is only in the kidney, the surgeon will remove the whole kidney (nephrectomy). If there are tumors in both kidneys or if the tumor has spread outside the kidney, a piece of the tumor will be removed. In any case, a sample of tissue from the tumor is sent to a pathologist, who looks at it under a microscope to check for signs of cancer.
Certain factors affect prognosis (chance of recovery) and treatment options.
The prognosis (chance of recovery) and treatment options depend on the following:
- How different the tumor cells are from normal kidney cells.
- The stage of the cancer.
- The type and size of the tumor.
- The age of the child.
- Whether the tumor can be completely removed in surgery.
- Whether the cancer has just been diagnosed or has recurred (come back).
- Whether there are any abnormal chromosomes or genes.
- Whether the patient is treated by pediatric experts with experience in treating patients with Wilms tumor.
Wilms tumors and other childhood kidney tumors are staged during surgery and with imaging tests.
The process used to find out if cancer has spread outside of the kidney to other parts of the body is called staging. The information gathered from the staging process determines the stage of the disease. It is important to know the stage in order to plan treatment.
For Wilms tumor, the stage is determined during the initial surgery and with the results from imaging tests. The following imaging tests may be done to see if cancer has spread to other places in the body:
- CT scan (CAT scan): A procedure that makes a series of detailed pictures of areas inside the body, such as the chest or brain, taken from different angles. The pictures are made by a computer linked to an x-ray machine. A dye may be injected into a vein or swallowed to help the organs or tissues show up more clearly. This procedure is also called computed tomography, computerized tomography, or computerized axial tomography.
- X-ray of the chest and bones: An x-ray is a type of energy beam that can go through the body and onto film, making a picture of areas inside the body.
- MRI (magnetic resonance imaging): A procedure that uses a magnet, radio waves, and a computer to make a series of detailed pictures of areas inside the body, such as the brain. This procedure is also called nuclear magnetic resonance imaging (NMRI).
- Bone scan: A procedure to check if there are rapidly dividing cells, such as cancer cells, in the bone. A very small amount of radioactive material is injected into a vein and travels through the bloodstream. The radioactive material collects in the bones and is detected by a scanner.
- Ultrasound exam: A procedure in which high-energy sound waves (ultrasound) are bounced off internal tissues or organs and make echoes. The echoes form a picture of body tissues called a sonogram. An ultrasound of the major heart vessels is done to stage Wilms tumor.
There are three ways that cancer spreads in the body.
The three ways that cancer spreads in the body are:
- Through tissue. Cancer invades the surrounding normal tissue.
- Through the lymph system. Cancer invades the lymph system and travels through the lymph vessels to other places in the body.
- Through the blood. Cancer invades the veins and capillaries and travels through the blood to other places in the body.
When cancer cells break away from the primary (original) tumor and travel through the lymph or blood to other places in the body, another (secondary) tumor may form. This process is called metastasis. The secondary (metastatic) tumor is the same type of cancer as the primary tumor. For example, if breast cancer spreads to the bones, the cancer cells in the bones are actually breast cancer cells. The disease is metastatic breast cancer, not bone cancer.
In addition to the stages, Wilms tumors are described by their histology.
The histology (how the cells look under a microscope) of the tumor affects the prognosis and the treatment of Wilms tumor. The histology may be favorable or anaplastic (unfavorable). Tumors with a favorable histology have a better prognosis and respond better to chemotherapy than those with anaplastic histology. Tumor cells that are anaplastic divide rapidly and do not look like the type of cells they came from. Anaplastic tumors are harder to treat with chemotherapy than other Wilms tumors at the same stage.
The following stages are used for both favorable histology and anaplastic Wilms tumors:
In stage I, the tumor was completely removed by surgery and all of the following are true:
- Cancer was found only in the kidney and did not spread to blood vessels of the kidney.
- The outer layer of the kidney did not break open.
- The tumor did not break open.
- A biopsy of the tumor was not done.
- No cancer cells were found at the edges of the area where the tumor was removed.
In stage II, the tumor was completely removed by surgery and no cancer cells were found at the edges of the area where the cancer was removed. Before the tumor was removed, one of the following was true:
- Cancer had spread out of the kidney to nearby soft tissue.
- Cancer had spread to blood vessels of the kidney.
In stage III, cancer remains in the abdomen after surgery and at least one of the following is true:
- Cancer spread to lymph nodes in the abdomen or pelvis (the part of the body between the hips).
- Cancer spread to or through the surface of the peritoneum (the layer of tissue that lines the abdominal cavity and covers most organs in the abdomen).
- A biopsy of the tumor was done during surgery to remove it.
- The tumor broke open before or during surgery to remove it.
- The tumor was removed in more than one piece.
In stage IV, cancer has spread through the blood to organs such as the lungs, liver, bone, or brain, or to lymph nodes outside of the abdomen and pelvis.
In stage V, cancer cells are found in both kidneys when the disease is first diagnosed. Each kidney will be staged separately as I, II, III, or IV.
Recurrent Wilms Tumor and Other Childhood Kidney Tumors
Recurrent cancer is cancer that has recurred (come back) after it has been treated.