Wilms tumor affects approximately one child per 10,000 worldwide before the age of 15 years.1 Incidence rates appear to be slightly elevated for U.S. and African blacks in comparison to whites, but are only half as great among Asians.
Etiology:
Rachel
Although there is a clear link between Wilms tumors and certain birth defect syndromes and genetic changes, most children with this type of cancer do not have any known birth defects or inherited gene changes.2
Researchers do not yet know exactly why some children have Wilms tumors, but they have made great progress in understanding how normal kidneys develop, as well as how this process can go wrong, leading to a Wilms tumor.
Signs & Symptoms:
Brandon Children with Wilm's Tumor may have a variety of different symptoms at presentation. However, the most common symptoms include:3
Swelling of the abdomen
Blood in urine
Abdominal pain
Decreased appetite
Weakness or tiredness
Fever
High blood pressure
Constipation
Diagnostic Procedures:
Brandon Due to the location of Wilm's tumor, there are a large amount of studies that assist in the daignosis. These studies include:3
Abdominal ultrasound
Abdominal Computed Tomography (CT)
Magnetic Resonance Imaging (MRI)
Blood and Urine tests
Biopsy
Histology:
Ashley Nephroblastoma, commonly referred to as a Wilm’s tumor, is a malignant tumor in the kidney. This disease is most commonly seen in children ages 2-5 and is characterized by 3 distinct histologic components: blastema, epithelial elements and stromal elements. 4 The epithelial cells are often seen as tubules that combine with undifferentiated cells that form rosette-like structures. 4 The blastema component can be identified in a number of patterns including diffuse, nodular, serpentine, or nesting. 4 The stromal characteristics most likely include a spindle like structure and appear fibrous. 4 Select the link http://www.youtube.com/watch?v=kj9BuM4vXnw5 to view an online video that describes the histology of a Wilm’s tumor in more detail and has great images. The images below demonstrate a Wilm’s tumor with each characterizing histological appearance.
Figure 1. Reprinted from PathPedia. 4
Lymph node drainage:
Ashley Because the brain doesn't contain lymph node channels, metastasis do not occur through lymphatics.6
Metastatic spread:
Amanuel Wilm’s tumor commonly metastasize to the lung.7 Other possible sites include:7
The other kidney [In 5% of patients with wilm’s tumor, both kidneys are involved]
Liver
Brain
Bones
Grading:
Amanuel The grading system used for wilm’s tumor is as follows:8
Lindsey NWTS-National Wilms' Tumor Study Staging System:9 Stage I: tumor limited to kidney and completely excised; surface of renal capsule intact; tumor not ruptured before or during removal; no residual tumor apparent beyond margins of resection Stage II: tumor extends beyond kidney but is completely excised; regional extension of tumor (ex: penetration through outer surface of renal capsule into perirenal soft tissues); vessels outside kidney substances infiltrated or contain tumor thrombus. Tumor may have been examined on biopsy, or there has been local spillage of tumor confined to flank. No residual tumor apparent at or beyond margins of excision Stage III: residual nonhematogenous tumor confined to abdomen, any of the following may occur: A. lymph nodes on biopsy found to be involved in hilus, periaortic chains, or beyond B. diffuse peritoneal contamination by tumor such as spillage of tumor beyond flank before or during surgery or by tumor growth that has penetrated through peritoneal surface C. implants found on peritoneal surfaces D. tumor extends beyond surgical margins either microscopically or grossly E. tumor not completely excisable because of local infiltration into vital structures Stage IV: hematogenous metastases; deposits beyond Stage III (ex: lung, liver, bone, brain) Stage V: bilateral renal involvement at diagnosis; attempt should be made to stage each side according to the above criteria on the basis of extent of disease before biopsy
Radiation side effects:
Lindsey -doses > 24Gy associated with greater risk of scoliosis9 -musculoskeletal abnormalities -second malignant neoplasms -intestinal obstruction-risk greater when RT initiated within 10 days of surgery -few develop arterial hypertension or renal insufficiency -late toxicity in long term survivors: neuropsychologic sequale and second malignant tumors
Prognosis:
Kevin 4-year survival rates of NWTS-3 patients10 Relapse Free RateI (FH): 90% II (FH): 88% III (FH): 79% IV (FH): 75% I-III (UH): 65% IV (UH): 55%
Overall Rate I (FH): 96% II (FH): 92% III (FH): 86% IV (FH): 82% I-III (UH): 68% IV (UH): 55%
Treatments:
Kevin
General Management* The diagnosis of Wilms' tumor is usually made preoperatively and confirmed at surgery.
Preoperative therapy is not commonly practiced, although it has been examined in clinical trials.
Meticulous surgical techniques for exploring the abdomen through a transperitoneal incision are essential. The surgeon must excise all tumor, without spillage, if possible.
Thorough assessment and sampling of lymph nodes and inspection of the liver and opposite kidney should be performed.
Most favorable histology (FH) tumors are responsive to irradiaiton and chemotherapy.
Because of the potential long-term deleterious effects of radiaton therapy, it plays a relatively minor role compared with that of chemotherapy.
Unfavorable histology (UH) tumors are less responsive to either modality and generally are treated with aggressive multimodality regimens.
Radiation Therapy Techniques* Anesthesia or sedation is often required for daily treatment of these children.
Although radiation does not need to be given immediately after operation, treatment timing is important. Patients in whom irradiation was delayed for 10 days or more from surgery ahad a significantly higher chance of abdominal relapse, particularly those with UH tumors.
Because the pathologist cannot always rule out UH quickly, all patients with Wilms' tumors should be scheduled to start radiation within 10 days after surgery. Most patients with ultimately not be treated, but it is easier to cancel than to make arrangements to intiate irradiation for a small child on short notice.
No radiation therapy is needed for stage I and stage II FH tumors.
All other tumors should be treated to a dose of 10 Gy to the abdomen plus a 10 Gy boost to gross residual disease after surgery.
Patients with disease confined to the operative site need only flank irradiaiton, even if there has been local spillage of tumor.
Parallel-opposed fields using 4 to 6 MV photon are preferred.
Treatment portals should encompass the tumor bed and site of the excised kidney with a 2 to 3 cm margin. The medial border must cross the midline to include the entire width of the vertebrae to minimize growth disturbances.
A tangential abdominal wall shield can be used.
When whole-abdomen irradiation is administered, shaped portals must be used, and the femoral heads and acetabulum must be shielded.
Whole lung irradiation is used if there are lung metastases.
Dosages for FH bilateral Wilms' tumor should be limited to 10 Gy to the second kidney.11
TD 5/5:
Jenn Tissue dose associated with 5% injury rate within 5 years. (TD 5/5)12
Children with Wilm's Tumor may have a variety of different symptoms at presentation. However, the most common symptoms include:3
Due to the location of Wilm's tumor, there are a large amount of studies that assist in the daignosis. These studies include:3
Nephroblastoma, commonly referred to as a Wilm’s tumor, is a malignant tumor in the kidney. This disease is most commonly seen in children ages 2-5 and is characterized by 3 distinct histologic components: blastema, epithelial elements and stromal elements. 4 The epithelial cells are often seen as tubules that combine with undifferentiated cells that form rosette-like structures. 4 The blastema component can be identified in a number of patterns including diffuse, nodular, serpentine, or nesting. 4 The stromal characteristics most likely include a spindle like structure and appear fibrous. 4
Select the link http://www.youtube.com/watch?v=kj9BuM4vXnw 5 to view an online video that describes the histology of a Wilm’s tumor in more detail and has great images. The images below demonstrate a Wilm’s tumor with each characterizing histological appearance.
Because the brain doesn't contain lymph node channels, metastasis do not occur through lymphatics.6
Wilm’s tumor commonly metastasize to the lung.7
Other possible sites include:7
The grading system used for wilm’s tumor is as follows:8
NWTS-National Wilms' Tumor Study Staging System:9
Stage I: tumor limited to kidney and completely excised; surface of renal capsule intact; tumor not ruptured before or during removal; no residual tumor apparent beyond margins of resection
Stage II: tumor extends beyond kidney but is completely excised; regional extension of tumor (ex: penetration through outer surface of renal capsule into perirenal soft tissues); vessels outside kidney substances infiltrated or contain tumor thrombus. Tumor may have been examined on biopsy, or there has been local spillage of tumor confined to flank. No residual tumor apparent at or beyond margins of excision
Stage III: residual nonhematogenous tumor confined to abdomen, any of the following may occur:
A. lymph nodes on biopsy found to be involved in hilus, periaortic chains, or beyond
B. diffuse peritoneal contamination by tumor such as spillage of tumor beyond flank before or during surgery or by tumor growth that has penetrated through peritoneal surface
C. implants found on peritoneal surfaces
D. tumor extends beyond surgical margins either microscopically or grossly
E. tumor not completely excisable because of local infiltration into vital structures
Stage IV: hematogenous metastases; deposits beyond Stage III (ex: lung, liver, bone, brain)
Stage V: bilateral renal involvement at diagnosis; attempt should be made to stage each side according to the above criteria on the basis of extent of disease before biopsy
-doses > 24Gy associated with greater risk of scoliosis9
-musculoskeletal abnormalities
-second malignant neoplasms
-intestinal obstruction-risk greater when RT initiated within 10 days of surgery
-few develop arterial hypertension or renal insufficiency
-late toxicity in long term survivors: neuropsychologic sequale and second malignant tumors
4-year survival rates of NWTS-3 patients10
Relapse Free RateI (FH): 90%
II (FH): 88%
III (FH): 79%
IV (FH): 75%
I-III (UH): 65%
IV (UH): 55%
Overall Rate I (FH): 96%
II (FH): 92%
III (FH): 86%
IV (FH): 82%
I-III (UH): 68%
IV (UH): 55%
General Management* The diagnosis of Wilms' tumor is usually made preoperatively and confirmed at surgery.
Radiation Therapy Techniques* Anesthesia or sedation is often required for daily treatment of these children.
Dosages for FH bilateral Wilms' tumor should be limited to 10 Gy to the second kidney.11
Tissue dose associated with 5% injury rate within 5 years. (TD 5/5)12
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