Wilms' Tumor

What is Wilms' tumor?

Wilms' tumor is a rare type of kidney cancer that primarily affects children. Most cases occur in children under age 5, though it can occasionally develop in older children and rarely in adults. The tumor usually affects one kidney, but in about 5 to 10 percent of cases, both kidneys are involved.

This cancer starts when kidney cells grow out of control and form a mass. The tumor can grow quite large before it causes symptoms. Many children are diagnosed when a parent notices a swollen belly or a firm lump in the abdomen. Wilms' tumor is named after Dr. Max Wilms, a German surgeon who first described it in 1899.

The good news is that Wilms' tumor is highly treatable. With modern treatments including surgery, chemotherapy, and sometimes radiation, survival rates are excellent. More than 90 percent of children with Wilms' tumor are cured. Early detection and treatment by pediatric cancer specialists are key to the best outcomes.

IGF-2

Checks growth hormone levels
Measures body's growth factor protein
Assesses hormone-related health issues

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Symptoms

A swollen belly or a noticeable lump in the abdomen
Abdominal pain or discomfort
Blood in the urine, which may appear pink or red
Fever without other signs of infection
Loss of appetite or nausea
High blood pressure in some cases
Constipation due to tumor pressure on the intestines
Fatigue or low energy levels

Many children with Wilms' tumor appear healthy and active despite having the disease. The abdominal swelling is often the only sign, discovered during bath time or diaper changes. Some children have no obvious symptoms until the tumor becomes large enough to cause discomfort.

Causes and risk factors

The exact cause of Wilms' tumor is not fully understood. Most cases occur sporadically, meaning they happen by chance with no clear family history. Scientists believe the cancer develops when kidney cells that should mature into normal tissue continue growing abnormally. Genetic changes play a role, including overexpression of the IGF-2 gene, which makes a protein that promotes cell growth.

Certain genetic conditions increase risk, including WAGR syndrome, Denys-Drash syndrome, and Beckwith-Wiedemann syndrome. Children born with aniridia, a condition where the iris of the eye is missing, have higher risk. Having undescended testicles or certain urinary tract abnormalities also increases likelihood. Family history matters, but only about 1 to 2 percent of cases run in families. Most children who develop Wilms' tumor have no known risk factors.

How it's diagnosed

Wilms' tumor is diagnosed through a combination of imaging tests and sometimes blood tests. When a doctor suspects the condition based on symptoms or physical exam, they will order an ultrasound or CT scan of the abdomen. These imaging tests can show the size and location of the tumor. An MRI may also be used to see if cancer has spread to other areas. Chest X-rays or CT scans check if the cancer has reached the lungs.

Blood tests are used to check overall health and kidney function before treatment begins. Some specialized tests may measure levels of certain proteins like IGF-2, which can be elevated in Wilms' tumor cases. A definitive diagnosis is usually made after surgery when the tumor tissue is examined under a microscope by a pathologist. Talk to a pediatric oncologist or specialist about the appropriate testing pathway for your child.

Treatment options

Surgery to remove the affected kidney and tumor, called nephrectomy
Chemotherapy with cancer-fighting medications before or after surgery
Radiation therapy in certain cases, especially if cancer has spread
Close monitoring with regular imaging and follow-up appointments
Treatment of high blood pressure if present
Nutritional support to maintain strength during treatment
Pain management as needed during recovery
Psychological support for child and family throughout treatment

Frequently asked questions

Wilms' tumor most commonly affects children between ages 3 and 4. About 75 percent of cases are diagnosed before age 5. It can occur in older children and even adults, but this is rare. Girls and boys are affected at roughly equal rates.

Wilms' tumor is a cancer that starts in kidney tissue, not an infection or functional kidney problem. Unlike kidney infections or kidney stones, Wilms' tumor involves uncontrolled cell growth. It requires cancer treatment rather than antibiotics or other standard kidney treatments. The tumor can be felt as a solid mass rather than causing typical kidney pain.

Blood tests alone cannot diagnose Wilms' tumor. Imaging tests like ultrasound and CT scans are needed to see the tumor. However, some blood tests can measure proteins like IGF-2 that may be elevated in cases of Wilms' tumor. Blood tests also help doctors assess kidney function and overall health before and during treatment.

The survival rate for Wilms' tumor is very high with modern treatment. More than 90 percent of children are cured, especially when the tumor is caught early and has not spread. Even children with more advanced disease often respond well to treatment. Outcomes depend on factors like tumor stage, cell type, and how well the cancer responds to chemotherapy.

Most cases of Wilms' tumor occur sporadically with no family history. Only about 1 to 2 percent of cases are inherited. However, certain genetic syndromes that run in families can increase risk. If your family has a history of Wilms' tumor or associated genetic conditions, talk to a genetic counselor about screening.

About 5 to 10 percent of children have tumors in both kidneys. This requires a more careful treatment approach to preserve kidney function. Doctors may use chemotherapy first to shrink tumors before surgery. The goal is to remove as much cancer as possible while saving enough healthy kidney tissue for the child to avoid dialysis.

Treatment duration varies based on tumor stage and response to therapy. Most children receive treatment for several months to about a year. This typically includes surgery followed by chemotherapy for weeks to months. Some children also need radiation therapy. After treatment ends, regular follow-up visits continue for several years to monitor for recurrence.

Recurrence is possible but not common with Wilms' tumor. Most children who are cured remain cancer-free. If cancer does return, it usually happens within the first two years after treatment. This is why regular follow-up with imaging tests is important. Recurrent Wilms' tumor can often still be treated successfully.

After treatment, watch for any new lumps, abdominal swelling, or persistent pain. Report fever, blood in urine, or unexplained weight loss to your doctor. Follow all scheduled follow-up appointments for imaging and physical exams. Long-term monitoring also checks for potential late effects of treatment on growth, kidney function, and heart health.

There is no known way to prevent Wilms' tumor because most cases occur randomly. Children with genetic syndromes that increase risk may benefit from regular ultrasound screening for early detection. Genetic counseling can help families understand their risk. Early detection through awareness of symptoms is the best approach for better outcomes.