Nephroblastoma – Diagnostics – Overview of Information and Clinical Research

Nephroblastoma, commonly known as Wilms tumor, is the most common type of kidney cancer in children. Understanding how doctors identify this condition is important for families facing a potential diagnosis. Early and accurate testing helps doctors create the best possible treatment plan for each child.

Who Should Undergo Diagnostics and When to Seek Testing

Parents and caregivers should consider seeking medical evaluation if their child shows certain warning signs. The most common reason families first visit a doctor is discovering a lump or swelling in the child’s belly area. This mass may be noticed during everyday activities like bathing, dressing, or changing diapers.^[1]

Not every child with Wilms tumor will show obvious symptoms, which is why awareness of subtle changes matters. Some children experience pain in the abdomen, though this is not always present. Other signs include blood appearing in the urine, which parents may notice as pink or red coloring. Fever without an obvious cause, high blood pressure, or a child becoming unusually tired or losing appetite should also prompt a medical visit.^[3]

Children with certain genetic conditions need regular monitoring even without symptoms. Those diagnosed with WAGR syndrome (which includes Wilms tumor, lack of the colored part of the eye, genital differences, and developmental delays) have about a 50% chance of developing this kidney cancer. Children with Denys-Drash syndrome face an even higher risk at 90%. Those with Beckwith-Wiedemann syndrome, an overgrowth condition where body parts grow larger than typical, have a 5% to 10% risk.^[3]

For children at elevated risk due to these genetic conditions, doctors recommend screening every three months until the child reaches at least age 8. This regular monitoring allows doctors to catch any tumors early, often before they cause symptoms.^[4]

⚠️ Important

If you discover a lump in your child’s abdomen, handle your child gently and avoid pressing on the area. The tumor should not be handled roughly before or during evaluation, as pressure could potentially cause the tumor to rupture and spread cancer cells to other body tissues.^[1]

Classic Diagnostic Methods

When a child visits the doctor with concerning symptoms, the healthcare provider begins with a thorough physical examination and complete medical history. During the physical exam, the doctor carefully presses on the child’s abdomen to feel for any masses or unusual swelling. This gentle palpation helps determine if there is a solid lump that requires further investigation.^[9]

Imaging Tests

Imaging studies are the primary tools doctors use to visualize what is happening inside the body. An abdominal ultrasound is often the first imaging test ordered when Wilms tumor is suspected. This test uses sound waves to create pictures of the kidneys and surrounding tissues. It is safe, painless, and does not use radiation. The ultrasound can show whether a tumor is present, reveal details about the kidney and its blood vessels, and help doctors determine if tumors exist in both kidneys or other parts of the abdomen.^[3]

A computed tomography scan, commonly called a CT scan, provides more detailed images than an ultrasound. This test uses a series of X-rays taken from different angles and combines them with computer processing to create cross-sectional images of the body. CT scans are particularly helpful for seeing the exact size and location of a tumor. Doctors usually perform CT scans with a contrast material, which is a special dye that makes certain tissues show up more clearly on the images. This helps distinguish the tumor from normal kidney tissue.^[3]

Because Wilms tumor can spread to the lungs, doctors often order a chest X-ray or chest CT scan to check whether cancer has traveled beyond the kidneys. An X-ray uses a small amount of radiation to create images of the chest area. If the cancer has spread to the lungs, this needs to be identified early so doctors can adjust the treatment plan accordingly.^[3]

Magnetic resonance imaging, or MRI, is another imaging option that uses powerful magnets, radio waves, and a computer to create detailed pictures of organs and tissues. MRI scans are especially useful for determining whether cancer has spread to lymph nodes (small organs that are part of the body’s infection-fighting system) or other nearby organs. This test does not use radiation, making it a safe alternative for certain situations.^[3]

Laboratory Tests

Blood and urine tests provide essential information about how well the kidneys and other organs are functioning. Blood tests can measure the levels of various substances in the blood, helping doctors assess kidney function and overall health. These tests also check liver function, which is important because Wilms tumor can sometimes affect the liver.^[9]

Blood clotting tests are performed to ensure the child’s blood can clot properly. This information is particularly important if surgery will be needed. Some blood tests can also detect whether the child has anemia, which means having too few red blood cells. Children with Wilms tumor sometimes develop anemia, which can cause fatigue and weakness.^[1]

Urine tests can reveal blood in the urine, even when it is not visible to the naked eye. While not all children with Wilms tumor will have blood in their urine, finding it can be an important clue for doctors.^[2]

Biopsy Considerations

A biopsy involves removing a small sample of tissue to examine under a microscope. This is the most definitive way to determine whether cells are cancerous. However, in Wilms tumor cases, doctors approach biopsies differently than for many other cancers. In most situations, doctors do not perform a biopsy before surgery because there is concern that taking a tissue sample could cause tumor cells to spread.^[3]

Instead, doctors often proceed directly to surgery to remove the tumor based on the imaging findings and clinical presentation. The entire removed tumor is then examined by a pathologist, a doctor who specializes in diagnosing diseases by examining tissues. This examination after removal provides complete information about the tumor type and characteristics without risking spread of cancer cells before treatment.^[9]

Staging the Cancer

Once Wilms tumor is confirmed, doctors determine the stage of the cancer. Staging describes how far the cancer has spread and helps doctors choose the most appropriate treatment. In the United States, Wilms tumor is staged from 1 to 5.^[9]

Stage 1 means the cancer is found only in one kidney and can be completely removed with surgery. Stage 2 indicates the cancer has spread beyond the kidney to nearby areas like fat or blood vessels, but surgery can still remove all of it. Stage 3 means cancer has spread to nearby lymph nodes or other places within the abdomen, or cancer cells may have spilled during surgery. Stage 4 indicates the cancer has traveled to distant parts of the body such as the lungs, liver, bones, or brain. Stage 5 means cancer cells are found in both kidneys at diagnosis, and each kidney’s tumor is staged separately.^[9]

⚠️ Important

Getting a second opinion is a reasonable step after a Wilms tumor diagnosis. Some families find it helpful to have another specialist review the imaging studies and other test results to confirm the diagnosis and staging. Your child’s healthcare team can help arrange this if you wish.^[4]

Diagnostics for Clinical Trial Qualification

Clinical trials are research studies that test new treatments or new ways of using existing treatments. When children with Wilms tumor are being considered for participation in a clinical trial, they undergo specific diagnostic tests to determine if they meet the study’s requirements.^[4]

Standard imaging tests including ultrasound, CT scans, and MRI are typically required to precisely measure the tumor size and location. These measurements serve as a baseline that researchers use to track how well the experimental treatment works. Trials may specify that certain imaging tests must be performed within a particular timeframe before enrollment, ensuring the most current information about the tumor is available.^[11]

Blood tests for clinical trials often go beyond routine testing. Researchers may need specific blood counts, kidney function values, and liver function measurements to fall within certain ranges. This ensures that children entering the trial are healthy enough to tolerate the experimental treatment and that results can be accurately compared across all participants.^[11]

For some trials, tissue samples from the tumor must be analyzed for specific genetic markers or molecular features. Scientists have identified several genes that can be altered in Wilms tumor, including genes called WT1, CTNNB1, and WTX. The presence or absence of these genetic changes might determine whether a child qualifies for a particular trial that targets those specific abnormalities.^[2]

Some research protocols require that the tumor be classified by its histology, which means how the cells look under a microscope. Wilms tumors are classified as having either favorable or unfavorable histology. Tumors with unfavorable histology contain cells that look very different from normal cells, a characteristic called anaplasia. Clinical trials may specifically enroll only children with one histology type or the other, so this classification through tissue examination becomes a key qualification criterion.^[11]

Cardiac function tests may be required for trials involving certain chemotherapy drugs that can affect the heart. An echocardiogram, which uses sound waves to create moving pictures of the heart, helps ensure the child’s heart is functioning well enough to safely receive the trial treatment.^[11]

For children with a family history of Wilms tumor or those with genetic syndromes, some trials request genetic counseling and possibly genetic testing. This testing examines the child’s DNA to look for inherited genetic changes that might have contributed to the cancer. Understanding these genetic factors helps researchers learn more about how Wilms tumor develops and who might be at risk.^[4]

Clinical trials maintain strict eligibility requirements to ensure participant safety and to generate reliable scientific data. While this means not every child with Wilms tumor will qualify for every trial, the diagnostic information gathered during this process still benefits the child by providing the healthcare team with a comprehensive understanding of their specific disease characteristics.^[11]

Prognosis and Survival Rate

Prognosis

The outlook for children with Wilms tumor has improved dramatically over the years due to advances in treatment. With appropriate care, most children with this kidney cancer can be cured. Several factors influence how well a child will respond to treatment and what their long-term outlook might be.^[1]

The stage of the cancer at diagnosis is one of the most important factors affecting prognosis. Children with lower-stage disease, where the cancer is confined to the kidney and can be completely removed, generally have excellent outcomes. Even when cancer has spread beyond the kidney, modern treatment approaches combining surgery, chemotherapy, and sometimes radiation therapy have proven very effective.^[9]

The type of cells seen under the microscope also matters significantly. Tumors with favorable histology respond better to treatment than those with unfavorable histology containing anaplastic cells. The presence of anaplasia indicates cells that look very abnormal and tend to be more resistant to chemotherapy. However, even children with unfavorable histology can be successfully treated, though they may require more intensive therapy.^[11]

The child’s age at diagnosis plays a role as well. Wilms tumor most commonly affects children between ages 3 and 5, and children in this age range tend to have good outcomes. The disease becomes less common after age 5, and when it occurs in older children or adults, it may behave somewhat differently.^[1]

Certain genetic changes within the tumor can also influence prognosis. Loss of genetic material from specific chromosomes, particularly chromosomes 1p, 1q, 11p15, and 16q, has been linked to a poorer outlook. Alterations in the TP53 gene are also associated with more challenging cases. However, doctors use this genetic information to tailor treatment, giving more intensive therapy to children whose tumors have these higher-risk features.^[2]

Survival Rate

Survival statistics for Wilms tumor are encouraging. For children younger than 20 years diagnosed with this kidney cancer, the 5-year relative survival rate is 93%. This means that 93% of children with Wilms tumor are alive five years after diagnosis, which represents remarkable success in pediatric cancer treatment.^[11]

Between 1975 and 2020, childhood cancer mortality decreased by more than 50%, with Wilms tumor contributing to this positive trend. This improvement reflects decades of collaborative research through cooperative groups that have steadily refined treatment approaches to maximize cure while minimizing side effects.^[11]

Survival rates vary depending on the stage and histology of the tumor. Children with stage 1 or 2 disease and favorable histology have survival rates exceeding 95%. Even children with more advanced stage 4 disease, where cancer has spread to distant sites like the lungs, have 5-year survival rates around 80-90% with modern treatment protocols.^[14]

Children with unfavorable histology or certain high-risk genetic features have somewhat lower survival rates, though still often above 70-80% with intensive treatment. Bilateral Wilms tumor, affecting both kidneys simultaneously, presents unique challenges but can still be successfully treated while preserving kidney function in many cases.^[11]

These statistics represent overall survival rates and provide general guidance. Each child’s situation is unique, and their individual prognosis depends on multiple factors including their specific disease characteristics, how well they respond to initial treatment, and their overall health. The healthcare team caring for your child can provide more personalized information based on their particular circumstances.^[14]

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