From
StayCurrentMD
Wilms Tumor: Audio Chapter
With Dr. peter ehrlich · hosted by Dr. Todd Ponsky
Part of
Wilms Tumor 20 items
Chapter 1 of 12 · Fundamentals
Differential diagnosis
Introduction and differential diagnosis of pediatric renal masses
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Educational content from recorded physician discussions — not medical advice. Talk to your (or your child's) care team about your situation.
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What the experts said
In North America, the Children's Oncology Group recommends primary nephrectomy and ureterectomy with lymph node sampling for the majority of renal tumors in children.
If a tumor is so large that it compromises the child's respiratory status, preoperative chemotherapy with biopsy is recommended rather than primary surgery.
Preoperative chemotherapy is recommended if the tumor extends into the inferior vena cava beyond the infrahepatic level.
If a child has only one functioning kidney, preoperative chemotherapy is recommended to avoid nephrectomy.
Children with bilateral renal tumors should receive preoperative chemotherapy rather than primary nephrectomy.
Complication rates are higher when liver or bowel resection is performed at the same time as nephrectomy for Wilms tumor.
If gross tumor is left behind or the tumor is only biopsied, it is treated as a stage 3 abdominal tumor requiring three-drug chemotherapy plus flank radiation.
Evidence suggests surgeons should be more cautious about primary nephrectomy when tumors reach 13-15 centimeters or larger due to higher risk of rupture.
There is no imaging study available that can distinguish between rhabdoid tumor, clear cell sarcoma, and Wilms tumor, or determine favorable versus unfavorable histology.
For biopsy, at least 10 cores should be taken, with data suggesting accuracy increases between 10 and 20 cores.
Fine needle aspiration or simple true-cut needle biopsy cannot diagnose anaplasia and cannot distinguish Wilms tumor from nephrogenic rests.
Most chemotherapy protocols prefer a single-lumen port due to lower infection risk.
Stage 1 Wilms tumor is defined as tumor limited to the kidney, completely resected, with no capsular invasion, no rupture or biopsy prior to removal, no renal sinus vessel involvement, negative margins, and negative lymph nodes.
Stage 2 Wilms tumor includes complete resection with regional extension such as renal capsule penetration, renal sinus soft tissue invasion, or blood vessel involvement outside the primary kidney.
Stage 3 Wilms tumor includes biopsied tumors with gross residual disease, positive lymph nodes, peritoneal surface penetration with implants, positive margins, microscopic residual from intraoperative spill, or piecemeal tumor removal.
Stage 4 Wilms tumor is defined by hematogenous metastases to lung, liver, bone, or brain.
A child with stage 1 or 2 abdominal disease and lung metastases would not receive abdominal radiation, whereas stage 3 abdominal disease with lung metastases would require both chemotherapy and abdominal radiation.
Stage 1-2 favorable histology Wilms tumor without lung disease receives two-drug chemotherapy (vincristine and dactinomycin) for 19 weeks with shorter duration and lower toxicity than three-drug regimens.
The main late effects of Wilms tumor treatment are renal failure, second malignancies, pregnancy problems in females, hypertension, and cardiovascular disease, primarily caused by radiation and doxorubicin.
Fifteen percent of girls who receive pulmonary radiation for Wilms tumor develop breast cancer.
A recent Children's Oncology Group study showed that approximately 40% of patients with pulmonary metastases who had complete response by 6 weeks did not require pulmonary radiation, with 80-85% remaining relapse-free.
When lung lesions persist after chemotherapy, 50-60% of single residual lesions biopsied are not cancer but may be scar tissue.
All patients with lung lesions assumed to be metastatic disease start with three-drug chemotherapy.
The SIOP protocols use preoperative chemotherapy for all patients with Wilms tumor, using higher doses of two common drugs, with evaluation at 4 and 8 weeks before proceeding to resection.
In SIOP protocols, predominantly blastema component after preoperative chemotherapy is considered a negative prognostic factor, though this does not apply to primary nephrectomy patients.
The main factor predicting outcome in stage 3 Wilms tumor is whether lymph nodes are positive.
Loss of heterozygosity at 1p and 16q chromosomes is a validated prognostic marker; patients with both have significantly worse outcomes regardless of stage.
Outcomes for stage 1 and 2 Wilms tumor are essentially identical between Children's Oncology Group and SIOP treatment approaches.
Some Wilms tumor patients develop acquired von Willebrand disease, which is usually clinically meaningless but has been reported to cause significant bleeding in rare cases.
Right-sided Wilms tumors can be close to the duodenum and superior mesenteric artery, with reported injuries to these structures and the IVC due to anatomic distortion.
Taking a rim of diaphragm or liver capsule to avoid tumor violation does not upstage the tumor if the tumor itself is not divided.
A subset of patients with tumors less than 550g, stage 1, favorable histology, and age less than 2 years can be treated with surgery alone, with greater than 95% overall survival and 100% survival if they relapse.
Tumor extension into the renal vein or IVC is not a negative prognostic factor for Wilms tumor.
If IVC tumor thrombus extends out of the renal vein in one piece without adherence, it is considered stage 2 disease.
The major complication rate for primary surgery with tumor thrombus extending beyond the infrahepatic IVC is 26-30%, including mortality.
Patients with loss of heterozygosity at both 1p and 16q (5-7% of patients) receive intensified treatment: stage 1-2 patients add doxorubicin, and stage 3-4 patients receive five-drug chemotherapy (regimen M).
Stage 1-2 patients with loss of heterozygosity at 1p and 16q had approximately 10% lower overall survival than those without these markers.
Unfavorable histology Wilms tumor is classified as either diffuse anaplastic or focal anaplastic, with different treatments depending on the extent of anaplasia seen on high-powered fields.
Clear cell sarcoma of the kidney has reasonable treatment outcomes for low stages, but rhabdoid tumors have terrible outcomes except for stage 1, with most presenting at stage 3 or 4.
Bilateral Wilms tumors represent 8-10% of all Wilms tumor cases.
Event-free survival for unilateral Wilms tumor is approximately 88% and overall survival is 95%, compared to 61% event-free and 80% overall survival for bilateral Wilms tumors on NWTS-5.
The maximum response of most children with Wilms tumor to chemotherapy occurs by 12 weeks.
In a recent COG study of 250 bilateral Wilms tumor patients enrolled without mandatory biopsy, only one patient turned out to have rhabdoid tumor, and one report of bilateral clear cell sarcoma came from Asia.
When bilateral renal tumors are biopsied, both kidneys should be sampled because there is discordant pathology in up to 20% of patients.