Wilms' tumor, or nephroblastoma, is a rare type of kidney cancer. It usually affects children before the age of 6 years and is very rare in adults.

Max Wilms, a German doctor, first described the tumor in 1899, giving the disease its name.

Wilms' tumor is the most common kidney tumor in people under 15 years of age.

In this article, we will cover the signs and symptoms, diagnosis, and treatment.

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Wilms' tumors develop in children's kidneys and may start forming before birth.

Wilms' tumors are rare, but they are the most common malignant tumors of the kidneys in children.

They occur around the ages of 3 to 4 years and only very rarely after the age of 6 years. In the United States, 500–600 people report a Wilms' tumor each year.

Over three-quarters of cases occur in otherwise healthy children, while one quarter have links to other developmental problems.

Treatment usually has a high success rate. Over 90 percent of people who receive treatment will survive for at least 5 years.

For most people, the tumor occurs in one kidney, although more than one tumor might develop. In some cases, the tumor develops in both kidneys. It might develop from immature kidney cells or faulty genes.

A person might experience no symptoms during the early stages. Even a fairly large tumor may be painless. However, a doctor often finds these tumors before they start to metastasize, or spread to other parts of the body.

If symptoms occur, they may include:

  • swelling in the abdomen
  • blood in the urine and abnormal urine color
  • fever
  • poor appetite
  • high blood pressure
  • abdominal or chest pain
  • nausea
  • constipation
  • large and distended veins across the abdomen
  • malaise, or feeling unwell
  • vomiting
  • unexplained weight loss

If the tumor spreads to the lungs, it can cause coughing, blood in the sputum, and difficulty breathing.

Treatment for Wilms' tumor depends on several factors, including:

  • age
  • overall health
  • medical history
  • the extent of the condition
  • tolerance to certain medications or procedures
  • parental preferences

Standard treatment usually involves surgery, chemotherapy, and sometimes radiation therapy.

Wilms' tumor is rare, and the doctor may advise that a pediatric cancer center takes care of treatment.

Surgery

Options for surgery include a nephrectomy, which is the surgical removal of kidney tissue.

Variations include:

  • Simple nephrectomy: The surgeon removes the whole kidney. The other kidney is enough to maintain the patient in good health.
  • Partial nephrectomy: The surgeon removes the tumor and part of the surrounding kidney tissue. This type of surgery is only necessary if the other kidney is not totally healthy, or if a surgeon has already removed the other kidney.
  • Radical nephrectomy: The surgeon removes the whole kidney, nearby adrenal gland, and lymph nodes, as well as other surrounding tissue at risk of metastasis.

During the procedure, the surgeon may check both kidneys, as well as the abdominal cavity. The surgeon may also take samples for testing.

Other treatment options

Other options include:

  • Kidney transplant: If removal is necessary for both kidneys, a person will need dialysis until a surgeon can provide a kidney transplant.
  • Chemotherapy: Chemotherapy kills cancer cells using medication. Doctors will first examine the tumor cells to determine whether they are aggressive or susceptible to chemotherapy.

Cytotoxic medication prevents cancer cells from dividing and growing.

Chemotherapy targets cancer cells but can also affect healthy cells, causing severe side effects.

These include:

  • hair loss
  • loss of appetite
  • low white blood cell count
  • nausea
  • vomiting

Once the treatment finishes, side effects usually resolve.

High-dose chemotherapy can destroy bone marrow cells. If the individual requires a high dose, the doctor may remove and freeze marrow cells, returning them to the body intravenously after the treatment.

Radiation therapy: Beams of high-energy X-rays or particles of radiation destroy cancer cells. Radiation therapy works by damaging the DNA inside the tumor cells and destroying their ability to reproduce.

Radiation therapy usually begins a few days after surgery. Very young people with Wilm's tumor may receive a sedative so that they remain still during a radiotherapy session.

The doctor marks the targeted area with a dye while shielding non-targeted areas of the body.

The following side effects are possible:

  • Diarrhea: If the doctor targets the abdomen with radiation, symptoms may occur a few days after starting treatment. As treatment progresses, symptoms may get worse. However, they usually resolve a few weeks after completing the course.
  • Fatigue: This is the most common symptom.
  • Nausea: This may occur at any time during treatment or for a short time after. Inform the doctor, as any nauseous feelings are easily treatable with medication.
  • Skin irritation: The radiation beam might cause redness and soreness. Be sure to protect these areas from sunlight, cold winds, from scratching and rubbing, and from perfumed soaps.

A medical team uses staging to assess how far a Wilms' tumor has grown or spread.

  • Stage 1: The cancer stays within the kidney, and surgical removal is possible.
  • Stage 2: The cancer has reached tissues and structures close to the kidney, such as blood vessels and fat. However, a surgeon can still completely remove the tumor at this stage.
  • Stage 3: The cancer has spread further and has reached nearby lymph nodes or other parts of the abdomen. Complete surgical removal may not be possible.
  • Stage 4: The cancer has spread to distant parts of the body, such as the brain, liver, or lungs.
  • Stage 5: Both kidneys have cancer cells.

Treatment by stages

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Successful treatment depends on the stage at which a doctor identifies the cancer.

The stage of the cancer dictates how a medical team would treat a Wilms' tumor.

Stages 1 or 2: If the cancer cell type is not aggressive, a surgeon will remove the kidney, surrounding tissues, and some nearby lymph nodes.

Chemotherapy often follows surgery at this stage. Some people with a stage-2 Wilms' tumor might also need radiation therapy.

Stages 3 or 4: If the cancer has spread into the abdomen, removal might damage major blood vessels or other key structures.

In this case, the medical team will use a combination therapy of surgery, radiation, and chemotherapy. Chemotherapy might also help shrink the tumor before the surgery.

Stage 5: If both kidneys have tumor cells, surgeons will remove part of the cancer from each kidney. They will also examine nearby lymph nodes to determine whether they also contain cancer cells.

After this, the individual will receive chemotherapy to shrink the remaining tumor. Later, surgeons remove more of the tumor. The surgeon will try to spare as much healthy kidney tissue as possible.

More radiation therapy and chemotherapy may follow these procedures.

Research continues into the exact cause of a Wilms' tumor, but it most likely starts with faulty kidney cell development before birth.

The abnormal cells multiply in their primitive state and become a tumor, which is usually detectable at the age of 3 to 4 years.

Genetic factors: Genes that control cell growth mutate, or change, allowing cells to divide and grow in an out of control manner. Researchers have studied two genes: Wilms Tumor 1 or 2 (WT1 or WT2). Mutations might also occur in other chromosomes.

Family history: Wilms tumors may stem from a genetic anomaly that a parent passes on. However, this does not seem to be the case for most Wilms' tumors. In fewer than 2 percent of cases, a close relative has or had the same type of cancer.

Most Wilms tumors occur by chance. They are sporadic, resulting from genetic mutations that affect cell growth in the kidney. These changes usually start after birth.

Co-occurring conditions

Some conditions occur alongside a Wilms' tumor.

WAGR syndrome: In a small number of people, a tumor appears alongside other genetic conditions.

WAGR is an acronym, standing for four conditions:

  • Wilms' tumor
  • aniridia, or being born with no iris, the part of the eye with color
  • genitourinary malformations, or physical anomalies in the genitals and urinary system
  • delayed cognitive development

WAGR happens when chromosome 11 loses or deletes the WT1 gene. WT1 is a gene that holds back, or suppresses, the growth of tumors and controls cell growth.

A person with WAGR syndrome has a 45 to 60 percent chance of developing Wilm's tumor.

Denys-Drash syndrome (DDS): This is a very rare disorder that causes kidney failure before the age of 3 years. Inactive or lost WT1 also causes this disorder.

DDS causes anomalies in developing sexual organs. It also presents a high risk of a Wilms' tumor, as well as some other types of cancer.

Beckwith-Wiedemann syndrome: This is an overgrowth disorder with a wide range of symptoms, including

  • a significantly higher-than-normal birth weight
  • a large tongue
  • enlarged organs, especially the liver
  • overgrowth of one side of the body
  • low blood sugar in the newborn period
  • ear creases
  • ear pits
  • asymmetrical growth throughout the body

It may result from an overactive oncogene copy on chromosome 11 (IGF2). Oncogenes regulate cell growth. If an error occurs in the oncogene, cell growth might get out of control.

Beckwith-Wiedemann syndrome increases the risk of developing a Wilms' tumor and also hepatoblastoma, neuroblastoma, adrenocortical cancer, and rhabdomyosarcoma.

Other factors

Some other factors make a Wilm's tumor more likely, including:

  • Sex: Females have a slightly higher risk of developing a Wilms' tumor than males.
  • Ethnic origin: People of black African ancestry have a slightly higher probability of developing Wilms' tumors. In the United States, Asian-Americans have the lowest risk.
  • Cryptorchidism: The failure of one or both testicles to descend into the scrotum may increase the risk of developing Wilms' tumors.
  • Hypospadias: Males born with the urethra not located where it should be, at the tip of the penis, have a higher risk of developing Wilms' tumors.

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An abdominal ultrasound may support a diagnosis of a Wilms' tumor.

The doctor will ask about the signs and symptoms, check the child's medical history and details about the pregnancy, and carry out a physical examination.

They will carry out the following tests:

  • Blood test: This cannot diagnose a Wilms' tumor on its own but can help provide information about the individual's overall state of health and the condition of the liver and kidneys.
  • Urine test: This can assess for sugar, protein, blood, and bacteria.
  • Abdominal ultrasound scan: This provides an inside view of soft tissues and cavities. It also provides an outline of the kidneys and any tumors growing there.

An abdominal ultrasound can detect problems in the renal veins or other veins in the abdomen. The doctor will check both kidneys.

Other imaging techniques that can help identify Wilms' tumors include a CT scan or an MRI.

A chest X-ray can show whether the tumor has spread into the lungs.

The doctor may also take a biopsy. In this procedure, the doctor takes a small piece of the tumor and examines it under a microscope.

A Wilm's tumor can be favorable or anaplastic. Anaplastic Wilms' tumors are more difficult to treat and cure. Anaplasia occurs when the nuclei of the cells are large and distorted.

A favorable Wilms' tumor has a high success rate for treatment. Around 90 percent of all Wilms' tumor diagnoses are favorable.

Apart from this, other factors that can affect the outlook include:

  • the stage of the cancer
  • the size of the primary tumor
  • the age and general health of the person at the point of diagnosis
  • response to therapy and whether a surgeon is able to remove the tumor
  • how well the individual tolerates specific medications, procedures, or therapies
  • the presence of any underlying genetic changes

Prompt and aggressive therapy is likely to provide the best outcome. Follow-up care is also essential.

For those aged under 15 years at the time of diagnosis, the chance of surviving 5 years or more was 88 percent in 2010, compared with 74 percent in 1975.

According to the American Cancer Society, the chance of surviving at least 4 years is:

  • For diagnosis at stage 1: 83 percent for an anaplastic tumor and 99 percent for a favorable histology
  • For diagnosis at stage 5: 55 percent for an anaplastic tumor and 87 percent for a favorable histology