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Last updated: 7/17/2023
Years published: 1987, 1990, 1994, 1995, 1998, 2005, 2019, 2023
NORD gratefully acknowledges Puja Darji, NORD Editorial Intern from the Massachusetts College of Pharmacy and Health Sciences, and Jennifer H. Aldrink, MD, FACS, FAAP, Professor of Clinical Surgery and Pediatrics, The Ohio State University College of Medicine, Division of Pediatric Surgery, Director of Surgical Oncology, Nationwide Children’s Hospital, for assistance in the preparation of this report.
Wilms’ tumor is a type of kidney cancer that typically occurs in young children. It is responsible for 95% of all malignant kidney tumors in patients under the age of 15 years old. Wilms’ tumor can occur in one kidney (unilateral) or in both kidneys (bilateral) and can spread throughout the rest of the body. There are about 650 new cases diagnosed each year in the United States with the average age of diagnosis being 2 to 5 years of age.
Young children with Wilms’ tumor often show no signs or symptoms. The first sign that is often seen in patients with Wilms’ tumor is a large lump in the abdomen, also known as a mass, and can be associated with abdominal pain and swelling. Most parents may not notice the mass until it is large enough to be felt when bathing or dressing the child. Other symptoms are more common in older children and may include pain, anemia, fever, blood in the urine, nausea or vomiting or both, constipation, loss of appetite, shortness of breath and high blood pressure. There may be severe abdominal pain if the tumor ruptures or bleeds.
Staging
There are 5 stages of Wilms’ Tumor:
Stage I indicates that the tumor stayed in the kidney without spreading outside the renal capsule showing no vascular invasion. This is the most common stage of Wilms’ tumor accounting for 40% of all Wilms’ tumors.
Stage II is when the tumor is confined to the kidney but involves the capsule around the kidney or the collecting system of the kidney. The tumor is still surgically removable since it is centralized to the kidney. This stage accounts for 20% of Wilms’ tumors.
Stage III indicates that the tumor has spread beyond the kidney. The margins of resection may contain tumor cells; the cancer may have spread to regional lymph nodes near the kidney or along the aorta or inferior vena cava. In addition, tumor that is spilled from the mass, either by biopsy or tumor rupture is also included in stage III.
Stage IV tumors are those that have spread through the vascular system. The tumor has spread through the blood to organs such as the lungs, liver, or rarely brain or bones. These account for about 10-15% of all Wilms’ tumors.
Stage V are those cases where both kidneys have tumors at the time of initial diagnosis. About 5-10% of all Wilms tumors are at this stage.
Kidneys start developing as the fetus grows in the womb. At about 3 years of age kidney cells become mature but in children with Wilms’ tumor, not all kidney cells mature. These immature kidney cells begin to cluster into a mass that grows out of control leading to a tumor in the kidney.
Changes (pathogenic variants or mutations) in several genes are known to cause Wilms’ tumor. The WT1 or WT2 genes on chromosome 11, WTX gene and the AMER1 gene on the X chromosome, as well as the CTNNB1 gene on chromosome 3 are genes that are deleted or altered in patients presenting with Wilms’ tumor. These genes signal cells for growth and cell division but variants in these genes can lead to overgrowth of certain body tissues. The reason for the changes in these genes is not known.
Some children have an underlying condition that is associated with Wilms’ tumor. One of the syndromes that has been linked to Wilms’ tumor is WAGR syndrome. Approximately 50% of children with WAGR syndrome will develop Wilms’ tumor. WAGR syndrome is a disorder that affects many body systems such as the eyes, brain and the genitourinary system. One of the first effects seen with WAGR syndrome is on the eye. Many people have what’s called aniridia which is an absence in the colored part of the eye, the iris. This can reduce sharpness in vision and increase sensitivity to light. Although the effects in the genitals and urinary tract happen in both genders, it is more common in males. WAGR syndrome can also have a negative impact on the brain leading to intellectual disability. An affected person may have trouble processing, learning, and properly responding to information. (For more information on this condition, search for “WAGR” in the Rare Disease Database.)
Other syndromes that increase the likelihood of getting Wilms’ tumor are Denys-Drash syndrome which is where the kidneys stop working in children at a very young age, Beckwith-Wiedemann syndrome where internal organs and limbs of children are enlarged, and Frasier syndrome where scar tissue forms within the small blood vessels in the kidney resulting in kidney failure. All related syndromes that increase the probability of a child getting Wilms’ tumor also have some alteration of the WT1 gene as well.
There are other risk factors or possible reasons for an increased risk of getting Wilms’ tumor such as having a family history. A family history of Wilms’ tumor is sometimes associated with variants in other genes different from the ones listed above. These variants occur in genes on chromosomes 16q and 1p and if the child has loss of heterozygosity, or LOH, meaning a loss of one of two copies of a chromosomal region, then the patient will be at a much higher risk.
Wilms’ tumor is the most common pediatric kidney cancer, and the fourth most common pediatric cancer overall. Wilms’ tumor affects approximately 1 in 10,000 children with the median age of onset being 3.5 years. Girls are slightly more likely than boys to develop Wilms’ tumor and African Americans are also at a higher risk.
To diagnose Wilms’ tumor the doctor will first take a full medical history of all past and present conditions, medications and family history. The doctor will then perform a physical examination. If the doctor is suspicious of Wilms’ tumor, he or she may obtain an ultrasound of the abdomen and/or kidneys to define where the mass is coming from.
The next step is to obtain a CT scan, which stands for computed tomography. A CT scan of the abdomen and chest provides detailed cross-sectional images of parts of the patient’s body, such as the kidneys and lungs. In a CT scan, the patient must lie very still on their back for the scans to come out clear. It is helpful for checking whether a cancer has grown into nearby veins or has spread to organs beyond the kidney. A CT scan may be useful in identifying a clot or tumor extension into the renal vein. If the cancer has spread to other organs in the patient’s body, then it is known to have metastasized (stage IV).
Another useful imaging test to diagnose Wilms’ tumor is a magnetic resonance imaging scan otherwise known as an MRI scan which uses no radiation but rather radio waves and strong magnets. An MRI shows the kidneys and abdominal organs well, but usually requires sedation in a young child, and is not good at looking for spread to the lung.
Lab tests also might be done to check urine and blood samples if the doctor suspects a kidney problem.
Staging and Treatment
Therapy depends on the stage of the tumor as well as if the patient has a family history of Wilms’ tumor. The most common treatment for Wilms’ tumor is unilateral nephrectomy which is the surgical removal of the affected kidney, and regional lymph node sampling. Chemotherapy drugs such as vincristine, dactinomycin, doxorubicin, cyclophosphamide, etoposide and carboplatin are used; however, vincristine and dactinomycin are used for lower stage (I and II) disease. Depending on the severity of the disease, a combination of these drugs may be used for aggressive treatment. Radiation after surgery may also be required depending on tumor histology and extent of spread.
Following recovery after surgical resection of the tumor, patients start treatment with systemic chemotherapy based upon stage and pathology. However, if the tumor is found to have LOH of both chromosomes 1p and 16q, or 1q gain, more aggressive therapy may be indicated.
Stage IV of the disease is considered to be metastatic, meaning the cancer has spread throughout the patient’s body, most often to the lungs. Systemic therapy and radiation therapy to the lungs is dependent upon treatment response of the metastases to the lungs. Children with bilateral Wilms’ tumor will be given doxorubicin, vincristine and dactinomycin prior to surgery in order to shrink the tumor and preserve as much renal tissue as possible.
With increasing new therapies such as chemotherapy the survival rate for Wilms’ tumor in the United States over 5 years is excellent at 92%.
Information on current clinical trials is posted on the Internet at www.clinicaltrials.gov. All studies receiving U.S. government funding, and some supported by private industry, are posted on this government website.
For information about clinical trials being conducted at the NIH Clinical Center in Bethesda, MD, contact the NIH Patient Recruitment Office:
Tollfree: (800) 411-1222
TTY: (866) 411-1010
Email: [email protected]
Some current clinical trials also are posted on the following page on the NORD website:
https://rarediseases.org/for-patients-and-families/information-resources/info-clinical-trials-and-research-studies/
For information about clinical trials sponsored by private sources, contact:
https://www.centerwatch.com/
For information about clinical trials conducted in Europe, contact:
https://www.clinicaltrialsregister.eu/
JOURNAL ARTICLES
Aldrink JH, Heaton TE, Dasgupta R, et al. Update on Wilms tumor. J Pediatr Surg. 2019;54(3):390-397.
Bahrami A, Joodi M, Maftooh M, et al. The genetic factors contributing to the development of Wilm’s tumor and their clinical utility in its diagnosis and prognosis. J Cell Physiol. 2018;233(4):2882-2888.
Caldwell BT, Wilcox DT, Cost NG. Current Management for Pediatric Urologic Oncology. Adv Pediatr. 2017;64(1):191-223.
Charlton J, Irtan S, Bergeron C, Pritchard-jones K. Bilateral Wilms tumour: a review of clinical and molecular features. Expert Rev Mol Med. 2017;19:e8.
Davidoff AM. Wilms tumor. Adv Pediatr. 2012;59(1):247-67.
INTERNET
Wilms tumor. Genetics Home Reference. NIH. U.S. National Library of Medicine. Reviewed July 13, 2023. https://ghr.nlm.nih.gov/condition/wilms-tumor Accessed July 17, 2023.
Frasier syndrome. Genetics Home Reference. NIH. U.S. National Library of Medicine. Reviewed March 2013. https://ghr.nlm.nih.gov/condition/frasier-syndrome Accessed July 17, 2023.
WAGR syndrome. Genetics Home Reference. NIH. U.S. National Library of Medicine. Reviewed June 28, 2023. https://ghr.nlm.nih.gov/condition/wagr-syndrome Accessed July 17, 2023.
Chronic Kidney Disease. IWSA. About WAGR – Associated Conditions Accessed July 17, 2023.
Wilms Tumor and Other Childhood Kidney Tumors Treatment. National Cancer Institute. Updated: August 18, 2021. https://www.cancer.gov/types/kidney/patient/wilms-treatment-pdq Accessed July 17, 2023.
Wilms Tumor Stages. American Cancer Society. Last Revised: January 8, 2020. https://www.cancer.org/cancer/wilms-tumor/detection-diagnosis-staging/staging.html
Accessed July 17, 2023.
Key Statistics for Wilms Tumors. American Cancer Society. Last Revised: Jan 8, 2020 https://www.cancer.org/cancer/wilms-tumor/about/key-statistics.html Accessed July 17, 2023.
What Causes Wilms Tumors? American Cancer Society. Last Revised: October 17, 2018. https://www.cancer.org/cancer/wilms-tumor/causes-risks-prevention/what-causes.html Accessed July 17, 2023.
Wilms Tumor. Childhood. Introduction. Cancer.Net. 01/2022. https://www.cancer.net/cancer-types/wilms-tumor-childhood/introduction
Accessed July 17, 2023.
Wilms Tumor – Childhood – Statistics. Cancer.Net. 03/2023. https://www.cancer.net/cancer-types/wilms-tumor-childhood/statistics Accessed July 17, 2023.
Rhabdoid Tumor. Dana. https://www.dana-farber.org/rhabdoid-tumor/ Accessed July 17, 2023.
Leslie SW, Sajjad H, Murphy PB. Wilms Tumor. [Updated 2023 May 30]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2023 Jan-. Available from: https://www.ncbi.nlm.nih.gov/books/NBK442004/ Accessed July 17, 2023.
Turner JT, Brzezinski J, Dome JS. Wilms Tumor Predisposition. 2003 Dec 19 [Updated 2022 Mar 24]. In: Adam MP, Mirzaa GM, Pagon RA, et al., editors. GeneReviews® [Internet]. Seattle (WA): University of Washington, Seattle; 1993-2023. Available from: https://www.ncbi.nlm.nih.gov/books/NBK1294/ Accessed July 17, 2023.
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