Modern treatment combines:
- Surgery
- Chemotherapy
- Radiotherapy in selected stages and histologies
Two established treatment strategies exist internationally.
One uses upfront nephrectomy followed by stage directed chemotherapy.
The other uses preoperative chemotherapy followed by nephrectomy, which reduces tumour size and intraoperative rupture risk.
Local paediatric oncology protocol should determine which pathway is followed because staging and postoperative treatment are protocol specific.
Upfront radical nephrectomy
For a unilateral resectable tumour:
Perform radical nephrectomy through a transabdominal approach.
Principles include:
- Explore abdomen
- Assess contralateral kidney if not adequately established by imaging
- Obtain regional lymph nodes
- Control renal vessels safely
- Remove kidney and tumour intact
- Avoid tumour rupture
Routine ipsilateral adrenalectomy is unnecessary when the adrenal gland is clearly uninvolved and can be safely preserved.
Lymph node sampling
Regional lymph node sampling is essential even when nodes appear normal.
Failure to sample nodes can understage the child and alter therapy incorrectly.
Remove suspicious nodes but do not perform an unnecessary radical retroperitoneal lymphadenectomy.
Tumour thrombus
Renal vein or IVC tumour extension does not automatically make disease unresectable.
Low IVC thrombus can often be removed during nephrectomy.
Extensive thrombus approaching or entering the heart requires:
- Detailed vascular imaging
- Multidisciplinary planning
- Cardiac surgical involvement in selected cases
Preoperative chemotherapy can shrink extensive venous tumour thrombus and simplify resection.
Preoperative chemotherapy pathway
For localised disease, a commonly used preoperative course is:
Vincristine 1.5 mg/m² IV once weekly, maximum 2 mg, for 4 weeks
plus
Dactinomycin 45 micrograms/kg IV, maximum 2 mg, during weeks 1 and 3.
For children below approximately 12 kg, protocols may reduce doses to approximately two thirds because toxicity is greater in very small children.
Metastatic disease commonly receives a longer preoperative regimen with addition of doxorubicin.
One African adapted protocol uses:
Doxorubicin 30 mg/m² IV at specified treatment weeks together with vincristine and dactinomycin before nephrectomy.
Do not improvise dosing between protocols. Chemotherapy should follow one complete paediatric oncology protocol because age, weight, histology, stage and radiotherapy interact.
Stage I and II favourable histology
After upfront nephrectomy, low stage favourable histology disease is commonly treated with vincristine plus dactinomycin.
A standard EE 4A programme administers these agents over approximately 18 weeks.
Routine flank radiotherapy is generally unnecessary for completely resected stage I and II favourable histology disease.
Stage III favourable histology
Treatment usually requires:
- Nephrectomy
- Vincristine
- Dactinomycin
- Doxorubicin
- Abdominal or flank radiotherapy according to extent of contamination and residual disease
A standard DD 4A chemotherapy programme runs for approximately 24 weeks.
When postoperative radiotherapy is indicated, avoid unnecessary delay. Starting more than approximately 14 days after nephrectomy has been associated with poorer outcomes in nonmetastatic disease.
Stage IV
Treat both the renal primary and metastatic disease.
Pulmonary metastases are common.
Systemic therapy is intensified according to:
- Histology
- Molecular features
- Response of pulmonary lesions
- Whether metastases can be completely resected
Children whose lung nodules disappear completely with chemotherapy may avoid whole lung radiation in selected modern protocols, whereas incomplete responders generally require additional systemic treatment and pulmonary radiotherapy.
Persistent isolated pulmonary nodules can require surgical excision to establish whether viable tumour remains.
Bilateral Wilms tumour
The objective in stage V disease is cure while preserving enough renal parenchyma to avoid lifelong renal failure.
Use preoperative chemotherapy to reduce tumour size.
Reimage after response.
Perform nephron sparing surgery wherever oncologically feasible.
Options include:
- Bilateral partial nephrectomy
- Radical nephrectomy on the more extensively involved side plus partial nephrectomy contralaterally
Avoid bilateral radical nephrectomy whenever an oncologically safe nephron preserving strategy remains possible.
Tumour rupture
Tumour rupture or operative spill increases local recurrence risk and usually places the patient into a higher local treatment category.
Prevention requires:
- Gentle handling
- Wide adequate incision
- Avoidance of squeezing a giant tumour through a small access wound
- En bloc removal where possible
Anaplastic histology
Diffuse anaplasia requires more intensive treatment.
Regimens can include additional agents such as:
- Cyclophosphamide
- Etoposide
- Carboplatin
along with radiotherapy according to stage.
Do not treat anaplastic disease using a favourable histology regimen.
Long term follow up
Surveillance includes assessment for:
- Local recurrence
- Pulmonary metastasis
- Renal function
- Hypertension
- Proteinuria
- Growth
- Doxorubicin related cardiomyopathy
- Radiotherapy related growth disturbance
- Second malignancy
Children with a solitary remaining kidney require lifelong renal protection and blood pressure surveillance.
Overall cure rates for localised favourable histology Wilms tumour are excellent, but successful treatment depends on correct staging, avoidance of tumour spill, adequate lymph node sampling and adherence to a complete multimodal protocol.
