Wilms' tumor

Medical quality assurance by Dr. Albrecht Nonnenmacher, MD at November 3, 2016
StartWilms' tumor

Wilms’ tumor (also known as Wilms tumor or nephroblastoma) is a type of kidney cancer that occurs mostly in children. It represents 6 to 8 percent of cancers found in children and is the most common kidney cancer that affects children.


Definition & Facts

The Wilms’ tumor is a mixed tumor and contains several types of cells, including embryonic kidney cells. In the more treatable type of Wilms’ tumor ('favorable histology'), the cells look somewhat abnormal. This type of cancer responds better to treatment and accounts for 90 percent of Wilms' tumor cases. The anaplastic type of Wilms’ tumor cells look very abnormal. Anaplastic cells tend to look different from one another and have enlarged and distorted nuclei.

Wilms' tumor affects both boys and girls and most of its victims are under seven years old. Most of those victims are stricken between the ages of three and four. The disease affects approximately 7 in 100,000 children. The condition is slightly more common among African American children than Caucasian children, while Asian-American children have the lowest rate of Wilms’ tumor. It is unclear why this is.

Symptoms & Complaints

At first, the child may have no symptoms of the disease. As it progresses, parents may notice a lump or mass in the child’s abdomen. It is described as smooth, large and firm. There may also be blood in the urine (hematuria), which presents as cloudy urine.

The child may have low grade fever, loss of appetite, and pallor. They may grow lethargic and lose weight, complain of a stomach ache, and experience nausea and vomiting. They may have high blood pressure and a general feeling of being sick. These symptoms can be signs of many illnesses and conditions, but if they persist, the parent should take the child to the doctor.


It is believed that Wilms’ tumor may originate from kidney cells that did not mature while the fetus was developing the womb. The cause for why these cells did not develop the way they should have is unknown. A certain amount of genetic changes affecting tumor suppressor genes have been identified as being associated with Wilms' tumor. Changes in the WT1 gene and the WT2 gene are associated with Wilms' tumor as are changes in the WTX gene. These genetic mutations are probably not inherited, and there are no environmental factors associated with Wilms' tumors.

Wilms’ tumor seems to be a greater risk for children who have an underdeveloped iris, which is the colorful part of the eye (aniridia). Other children who seem more at risk are those with one side of their body noticeably larger than the other side. Boy babies who are born with testicles (cryptorchidism) or a urethra that opens underneath the penis are also at higher risk for Wilms’ tumor.

Some medical experts classify the high risk child as having WAGR syndrome. This stands for:

Diagnosis & Tests

A doctor who suspects a child patient has a Wilms’ tumor gives them a blood test and clinical urine tests. These tests do not actually find the tumor, but let the doctor know the state of the child’s overall health. The tumor is diagnosed through an ultrasound, which is followed up with a computed tomography (CT) scan of the child’s pelvis, abdomen, and chest. This checks for the spread of the disease. Doctors recommend that children who have the above-mentioned birth defects have an ultrasound and physical examination every three or four months until they turn eight.

Treatment & Therapy

Treatment depends on the stage of the cancer. Wilms’ tumor is one of the few tumors that has a Stage 5. Stage 5 means that the tumor is found in both kidneys. Each kidney is then staged separately. The other stages are:

  • Stage 1: This stage means that the cancer has not spread outside of the kidney. About 40 percent of Wilms’ tumor patients are diagnosed at this stage. The treatment for Stage 1 is surgery. Surgery can remove the diseased part of a kidney or all of a kidney. Humans can live healthy lives with just one kidney. Surgery can also remove parts of both kidneys or all of both kidneys. In the latter case, the child needs to go on dialysis to filter their blood or have a kidney transplant
  • Stage 2. The cancer has spread around the kidneys. Treatment for this stage of the disease is surgery followed by radiation, chemotherapy, or a combination of the two. Stage 2 represents 23 percent of Wilms’ tumor cases.
  • Stage 3. In this stage, the cancer has invaded the lymph nodes, the blood vessels and nearby organs. Because of this, surgery will not remove all of the cancer cells. However, as with Stage 2, the treatment is surgery, chemotherapy and radiation. Stage 3 also represents 23 percent of this type of cancer.
  • Stage 4. In Stage 4, the cancer has spread to distant sites in the body, including the liver, lungs, the bones, and the brain. Stage 4 Wilms’ tumor represents about 10 percent of this particular cancer. At this point, the child maybe too weak for surgery and may need radiation and chemotherapy to kill some of the cancer cells and shrink the tumor.

During or after treatment, the child may also receive anti-nausea drugs, pain relievers and antibiotics if they contract an infection during their treatment. Clinical trials, where new forms of treatment are tested, are also helpful when it comes to Wilms’ tumor. Some children benefit from alternative therapies such as vitamin supplements, special diets, acupuncture, or massage. Doctors consider children cured of Wilms' tumor if they live for two years without a recurrence. 

Prevention & Prophylaxis

Wilms’ tumor cannot be prevented. However, the prognosis for Wilms’ tumor is very favorable if the cancer cells are not anaplastic and if it is caught and treated early.