|Classification and external resources|
Cut section showing two halves of a nephroblastoma specimen. Note the prominent septa subdividing the sectioned surface and the protrusion of tumor into the renal pelvis, resembling botryoid rhabdomyosarcoma.
Wilms' tumor or nephroblastoma is cancer of the kidneys that typically occurs in children, rarely in adults. Its common name is an eponym, referring to Dr. Max Wilms, the German surgeon (1867–1918) who first described this kind of tumor.
Approximately 500 cases are diagnosed in the U.S. annually. The majority (75%) occur in otherwise normal children; a minority (25%) are associated with other developmental abnormalities. It is highly responsive to treatment, with about 90% of patients surviving at least five years.
Most nephroblastomas are unilateral, being bilateral in less than 5% of cases, although patients with Denys-Drash syndrome mostly have bilateral or multiple tumors. They tend to be encapsulated and vascularized tumors that do not cross the midline of the abdomen. In cases of metastasis it is usually to the lung. A rupture of Wilms' tumor puts the patient at risk of hemorrhage and peritoneal dissemination of the tumor. In such cases, surgical intervention by a surgeon who is experienced in the removal of such a fragile tumor is imperative.
Pathologically, a triphasic nephroblastoma comprises three elements:
Wilms' tumor is a malignant tumor containing metanephric blastema, stromal and epithelial derivatives. Characteristic is the presence of abortive tubules and glomeruli surrounded by a spindled cell stroma. The stroma may include striated muscle, cartilage, bone, fat tissue, fibrous tissue. The tumor is compressing the normal kidney parenchyma.
Wilms' tumors may be separated into 2 prognostic groups based on pathologic characteristics:
- Favorable - Contains well developed components mentioned above
- Anaplastic - Contains diffuse anaplasia (poorly developed cells)
Typical symptoms are:
- an abnormally large abdomen
- abdominal pain
- nausea and vomiting
- blood in the urine (in about 20% of cases)
- high blood pressure in some cases
The first sign is normally a painless abdominal tumor that can be easily felt by the doctor. An Ultrasound, Computed Tomography, or MRI are done first. A tumor biopsy is not typically performed due to the chance of upstaging the cancer and seeding the abdomen with malignant cells.
The overall 5-year survival is estimated to be approximately 90%, but for individuals the prognosis is highly dependent on individual staging and treatment. Early removal tends to promote positive outcomes.
Tumor-specific loss-of-heterozygosity (LOH) for chromosomes 1p and 16q identifies a subset of Wilms' tumor patients who have a significantly increased risk of relapse and death. LOH for these chromosomal regions can now be used as an independent prognostic factor together with disease stage to target intensity of treatment to risk of treatment failure. Genome-wide copy number and LOH status can be assessed with virtual karyotyping of tumor cells (fresh or paraffin-embedded).
Molecular biology 
Mutations of the WT1 gene on chromosome 11 p 13 are observed in approximately 20% of Wilms' tumors. At least half of the Wilms' tumors with mutations in WT1 also carry mutations in CTNNB1, the gene encoding the proto-oncogene beta-catenin.
Most cases do not have mutations in any of these genes.
Staging is determined by combination of imaging studies and pathology findings if the tumor is operable. Treatment strategy is determined by the stage:
Definitions of stages 
Stage I (43% of patients) 
For stage I Wilms' tumor, 1 or more of the following criteria must be met:
- Tumor is limited to the kidney and is completely excised.
- The surface of the renal capsule is intact.
- The tumor is not ruptured or biopsied (open or needle) prior to removal.
- No involvement of extrarenal or renal sinus lymph-vascular spaces
- No residual tumor apparent beyond the margins of excision.
- Metastasis of tumor to lymph nodes not identified.
Stage II (23% of patients) 
For Stage II Wilms' tumor, 1 or more of the following criteria must be met:
- Tumor extends beyond the kidney but is completely excised.
- No residual tumor apparent at or beyond the margins of excision.
- Any of the following conditions may also exist:
- Tumor involvement of the blood vessels of the renal sinus and/or outside the renal parenchyma.
- The tumor has been biopsied prior to removal or there is local spillage of tumor during surgery, confined to the flank.
- Extensive tumor involvement of renal sinus soft tissue.
Stage III (23% of patients) 
For Stage III Wilms' tumor, 1 or more of the following criteria must be met:
- Unresectable primary tumor.
- Lymph node metastasis.
- Tumor is present at surgical margins.
- Tumor spillage involving peritoneal surfaces either before or during surgery, or transected tumor thrombus.
Stage IV (10% of patients) 
Stage IV Wilms' tumor is defined as the presence of hematogenous metastases (lung, liver, bone, or brain), or lymph node metastases outside the abdomenopelvic region.
Stage V (5% of patients) 
Stage V Wilms’ tumor is defined as bilateral renal involvement at the time of initial diagnosis. Note: For patients with bilateral involvement, an attempt should be made to stage each side according to the above criteria (stage I to III) on the basis of extent of disease prior to biopsy.
Prognosis and treatment 
Statistics may sometimes show more favorable outcomes for more aggressive stages than for less ones, which may be caused by more aggressive treatment and/or random variability in the study groups. Also, a stage V tumor is not necessarily worse than a stage IV tumor.
|Stage||Histopathology||4 Year relapse-free survival (RFS) or event-free survival (EFS)||4 Year overall survival (OS)||Treatment|
|Stage I ||Favorable histology in children younger than 24 months or tumor weight less than 550g||85%||98%||Surgery only (should be done only within the context of a clinical trial)|
|Favorable histology in children older than 24 months or tumor weight more than 550g||94% RFS||98%||Nephrectomy + lymph node sampling followed by regimen EE-4A|
|Diffuse anaplastic||68% EFS||80%||Nephrectomy + lymph node sampling followed by regimen EE-4A and radiotherapy|
|Stage II||Favorable histology||86% RFS||98%||Nephrectomy + lymph node sampling followed by regimen EE-4A|
|Focal anaplastic||80% EFS||80%||Nephrectomy + lymph node sampling followed by abdominal radiotherapy and regimen DD-4A|
|Diffuse anaplastic||83% EFS||82%||Nephrectomy + lymph node sampling followed by abdominal radiotherapy and regimen I|
|Stage III||Favorable histology||87% RFS||94%||Nephrectomy + lymph node sampling followed by abdominal radiotherapy and regimen DD-4A|
|Focal anaplastic||88% RFS||100% (8 people in study)||Nephrectomy + lymph node sampling followed by abdominal radiotherapy and regimen DD-4A|
|Focal anaplastic (preoperative treatment)||71% RFS||71%||Preoperative treatment with regimen DD-4A followed by nephrectomy + lymph node sampling and abdominal radiotherapy|
|Diffuse anaplastic||46% EFS||53%||Preoperative treatment with regimen I followed by nephrectomy + lymph node sampling and abdominal radiotherapy|
|Diffuse anaplastic||65% EFS||67%||Immediate nephrectomy + lymph node sampling followed by abdominal radiotherapy and regimen I|
|Stage IV||Favorable histology||76% RFS||86%||Nephrectomy + lymph node sampling, followed by abdominal radiotherapy, bilateral pulmonary radiotherapy, and regimen DD-4A|
|Focal anaplastic||61% EFS||72%||Nephrectomy + lymph node sampling, followed by abdominal radiotherapy, bilateral pulmonary radiotherapy, and regimen DD-4A|
|Diffuse anaplastic||33% EFS||33%||Immediate nephrectomy + lymph node sampling followed by abdominalradiotherapy, whole-lung radiotherapy, and regimen I|
|Diffuse anaplastic (preoperative treatment)||31% EFS||44%||Preoperative treatment with regimen I followed by nephrectomy + lymph node sampling followed by abdominalradiotherapy, whole-lung radiotherapy|
|Stage V||Overall||61% EFS||80%|
|Favorable histology||65%||87%||Bilateral renal biopsies and staging of each kidney followed by preoperative treatment with regimen EE-4A (if disease in both kidneys ≤ stage II) or regimen DD-4A (if disease in both kidneys > stage II), followed by second-look surgery and possibly more chemotherapy and/or radiotherapy|
|Focal anaplastic||76%||88%||Bilateral renal biopsies and staging of each kidney followed by preoperative treatment with regimen I, followed by second-look surgery and possibly more chemotherapy and/or radiotherapy|
|Diffuse anaplastic||25%||42%||Bilateral renal biopsies and staging of each kidney followed by preoperative treatment with regimen I, followed by second-look surgery and possibly more chemotherapy and/or radiotherapy|
Risk factors 
See also 
- Beckwith-Wiedemann syndrome
- Denys-Drash syndrome
- National Wilms Tumor Study Group (NWTS)
- Virtual Karyotype for 1p and 16q LOH
- WAGR syndrome
- Perlman syndrome
- EBSCO database verified by URAC; accessed from Mount Sinai Hospital, New York
- WhoNamedIt.com: Max Wilms
- Guaragna, M. S.; et al., Fernanda Caroline; Assumpção, Juliana Godoy; Zambaldi, Lílian de Jesus Girotto; Cardinalli, Izilda Aparecida; Yunes, José Andrés; De Mello, Maricilda Palandi; Brandalise, Silvia Regina et al. (2010). "The Novel WT1 Gene Mutation p. H377N Associated to Denys-Drash Syndrome". Journal of Pediatric Hematology/Oncology 32 (6): 486–488. doi:10.1097/MPH.0b013e3181e5e20d. PMID 20562648.
- Stewenius, Y.; Jin, Y.; Ora, I.; De Kraker, J.; Bras, J.; Frigyesi, A.; Alumets, J.; Sandstedt, B. et al. (2007). "Defective Chromosome Segregation and Telomere Dysfunction in Aggressive Wilms' Tumors". Clinical Cancer Research 13 (22): 6593–6602. doi:10.1158/1078-0432.CCR-07-1081. PMID 18006759. , in turn citing Tournade, M. F.; Com-Nougué, C.; De Kraker, J.; Ludwig, R.; Rey, A.; Burgers, J. M.; Sandstedt, B.; Godzinski, J. et al. (2001). "Optimal duration of preoperative therapy in unilateral and nonmetastatic Wilms' tumor in children older than 6 months: Results of the Ninth International Society of Pediatric Oncology Wilms' Tumor Trial and Study". Journal of clinical oncology : official journal of the American Society of Clinical Oncology 19 (2): 488–500. PMID 11208843.
- Messahel, B.; Williams, R.; Ridolfi, A.; et al., Roger; Warren, William; Tinworth, Lorna; Hobson, Rachel; Al-Saadi, Reem et al. (2009). "Allele loss at 16q defines poorer prognosis Wilms tumour irrespective of treatment approach in the UKW1-3 clinical trials: a Children's Cancer and Leukaemia Group (CCLG) Study". Eur J Cancer 45 (5): 819–826. doi:10.1016/j.ejca.2009.01.005. PMID 19231157.
- Grundy, P. E.; Breslow, N. E.; Li, S.; et al., E; Beckwith, JB; Ritchey, ML; Shamberger, RC; Haase, GM et al. (2005). "Loss of heterozygosity for chromosomes 1p and 16q is an adverse prognostic factor in favorable-histology Wilms tumor: a report from the National Wilms Tumor Study Group". J Clin Oncol 23 (29): 7312–7321. doi:10.1200/JCO.2005.01.2799. PMID 16129848.
- Call K, Glaser T, Ito C, Buckler A, Pelletier J, Haber D, Rose E, Kral A, Yeger H, Lewis W (1990). "Isolation and characterization of a zinc finger polypeptide gene at the human chromosome 11 Wilms' tumor locus". Cell 60 (3): 509–20. doi:10.1016/0092-8674(90)90601-A. PMID 2154335.
- Huff V (1998). "Wilms tumor genetics". Am J Med Genet 79 (4): 260–7. doi:10.1002/(SICI)1096-8628(19981002)79:4<260::AID-AJMG6>3.0.CO;2-Q. PMID 9781905.
- Maiti S, Alam R, Amos CI, Huff V (2000). "Frequent association of beta-catenin and WT1 mutations in Wilms tumors". Cancer Res 60 (22): 6288–92. PMID 11103785.
- Rivera M, Kim W, Wells J, Driscoll D, Brannigan B, Han M, Kim J, Feinberg A, Gerald W, Vargas S, Chin L, Iafrate A, Bell D, Haber D (2007). "An X chromosome gene, WTX, is commonly inactivated in Wilms tumor". Science 315 (5812): 642–5. doi:10.1126/science.1137509. PMID 17204608.
- Ruteshouser EC, Robinson SM, Huff V (June 2008). "Wilms tumor genetics: mutations in WT1, WTX, and CTNNB1 account for only about one-third of tumors". Genes Chromosomes Cancer 47 (6): 461–70. doi:10.1002/gcc.20553. PMID 18311776.
- Unless otherwise specified in boxes, then reference is: Treatment of Wilms Tumor at National Cancer Institute. Last Modified: 03/29/2012
- GeneReviews/NCBI/NIH/UW entry on Wilms Tumor Overview
- Information from National Cancer Institute
- Wilms' tumor at the Open Directory Project
- Cancer.Net Wilms Tumor - Childhood