eMedicine Specialties > Urology > Cancer, Wilms Tumor and Neuroblastoma
Wilms Tumor: Treatment
Updated: May 5, 2009
Treatment
Medical Therapy
Chemotherapy is essential in the treatment of Wilms tumor (WT). Refinements in the combination, length, and mode of administration of the various chemotherapeutic agents have resulted from the successive NWTS trials and have helped to optimize survival rates while minimizing acute and chronic toxicities.
Chemotherapy protocols vary from study to study; however, the main agents administered include vincristine, dactinomycin, and doxorubicin.
In the SIOP trials, chemotherapy is administered up front to reduce tumor volume, thereby decreasing the risk of surgical spillage of tumor.
Radiation therapy is restricted to treatment of higher-stage (III and IV) disease.
Surgical Therapy
According to the NWTSG protocol, the first step in the treatment of Wilms tumor is surgical staging followed by radical nephrectomy, if possible.
Make a transverse abdominal incision and begin abdominal exploration. Exploration should include the contralateral kidney by mobilizing the ipsilateral colon and opening the Gerota fascia. Exploration of the contralateral kidney is currently not recommended because of the improvement in imaging techniques (CT scan, MRI). If bilateral disease is diagnosed, nephrectomy is not performed, but biopsy specimens are obtained. New protocols in the management of bilateral Wilms tumor are being explored. If the disease is unilateral, radical nephrectomy and regional lymph node dissection or sampling are performed.
If the tumor is unresectable, biopsies are performed and the nephrectomy is deferred until after chemotherapy, which, in most cases, will shrink the tumor. Contiguous involvement of adjacent organs is frequently overdiagnosed. The overall surgical complication rate for Wilms tumor is approximately 20%. If IVC thrombus is present, preoperative chemotherapy will reduce the cavotomy rate by 50%.
With bilateral Wilms tumor (6% of cases), surgical exploration, biopsies from both sides, and accurate surgical staging (including lymph node biopsy of both sides) are performed. This is followed by 6 weeks of chemotherapy that is appropriate to the stage and histology of the tumor. Then, reassessment is performed using imaging studies, followed by definitive surgery with (1) unilateral radical nephrectomy and partial nephrectomy on the contralateral side; (2) bilateral partial nephrectomy; and (3) unilateral nephrectomy only, if the response was complete on the opposite side. This approach dramatically reduces the renal failure rate following bilateral Wilms tumor therapy.
The overall 2-year survival rate is higher than 80% with this approach, and the nephrectomy rate drops by 50% in patients with bilateral Wilms tumor. Bilateral partial nephrectomy is possible after chemotherapy or, if the tumor on one side responds completely to chemotherapy, with no subsequent need for nephrectomy.
Tumor biomarkers, histology, and stage are the most important prognostic factors in cases of unilateral disease. Bilateral high-stage tumors with unfavorable histology are associated with a poor prognosis in spite of the multimodal therapy.
Preoperative Details
Multimodal therapy (ie, surgery, radiation, chemotherapy) is the key to success when treating Wilms tumor.
The NWTSG recommends preoperative chemotherapy (after initial exploratory laparotomy and biopsy) in the following situations:
- Intracaval tumor extension: This occurs in 5% of cases of Wilms tumor. It is associated with a 40% rate of surgical complications, even in experienced hands. Upfront chemotherapy after staging and biopsy reduces tumor and thrombus size, which account for 25% of surgical complications.
- Inoperable tumors: Large tumors that involve vital structures make resection difficult. The complication rate is high, and the incidence of tumor spill soilage is also high. Upfront chemotherapy reduces soilage by 50%.
- Bilateral Wilms tumor
SIOP advocates upfront chemotherapy without previous laparotomy and biopsy. The NWTSG suggests that this approach comprises a 1%-5% risk of treating a benign disease.
Chemotherapy without proper surgical staging (eg, staging by means of imaging studies only) may alter the actual initial stage of the disease by the time of surgery and may subsequently alter decisions regarding the adjuvant chemotherapy and radiation therapy, which is based on the surgical staging.
Intraoperative Details
Enter the Gerota (perinephric fascia) fascia to examine the kidney. In cases of unilateral tumor, perform a nephrectomy if the opposite side is normal. In cases of bilateral disease, excisional biopsy of visible tumor is indicated, followed by re-resection with nephron preservation after chemotherapy. Identify the involved nodes with clips to facilitate postoperative radiation therapy.
Postoperative Details
Postoperative chemotherapy and radiotherapy protocols are based on the surgical staging and follow the guidelines of the NWTSG.
- Stage I favorable histology and unfavorable histology or stage II favorable histology
- Nephrectomy
- Postoperative vincristine and actinomycin D (18 wk)
- Stage II focal anaplasia or stage III favorable histology and focal anaplasia
- Nephrectomy
- Abdominal radiation (1000 cGy)
- Vincristine, actinomycin D, and doxorubicin (24 wk)
- Stage IV favorable histology or focal anaplasia
- Nephrectomy
- Abdominal irradiation according to local stage
- Bilateral pulmonary irradiation (1200 cGy) with sulfamethoxazole and trimethoprim (Bactrim) prophylaxis for Pneumocystis carinii
- Chemotherapy with vincristine, actinomycin D, and doxorubicin
- Stage II and stage IV diffuse anaplasia
- Nephrectomy
- Abdominal irradiation
- Whole lung irradiation for stage IV
- Chemotherapy for 24 months with vincristine, actinomycin D, doxorubicin, etoposide, and cyclophosphamide
Follow-up
Follow-up care after treatment must be long (if possible, lifelong) because Wilms tumor may recur after several years. Follow-up consists of chest radiography and abdominal ultrasonography, CT scan, or MRI every 3 months for the first 2 years, every 6 months for another 2 years, and once every 2 years thereafter.
Complications
Surgical complications
- Small-bowel obstruction (7%)
- Hemorrhage (6%)
- Wound infection, hernia (4%)
- Vascular complications (2%)
- Splenic and intestinal injury (1.5%)
Long-term complications
- Renal function: The rate of chronic renal failure is 1% overall. Of these cases, 70% are children with bilateral Wilms tumor (WT). In unilateral Wilms tumor, the rate is 0.25%. Bilateral nephrectomy is the most common cause of chronic renal failure, followed by treatment-related causes such as radiation or surgical complications. Unrecognized renal disease, such as Denys-Drash syndrome, is rare but should be kept in mind. The damage produced by radiation is dose-dependent, and the rate of impairment in creatinine clearance is approximately 20% with total abdomen irradiation with less than 1200 rads.
- Cardiac function: Anthracyclines such as doxorubicin produce cardiac muscle impairment in 5% of those receiving a cumulative of 400 mg/m2. The overall incidence rate of some form of cardiac damage is 25% in those treated with anthracycline. The overall incidence of cardiac failure is 1.7%. The mean time to the onset of cardiac failure is 8 years (according to NWTSG-2 and NWTSG-3). If lung irradiation is added, the rate of cardiac failure is 5.4%.
- Pulmonary function: Radiation pneumonitis is encountered in 20% of the cases receiving total pulmonary radiation. The rate of diffuse interstitial pneumonitis with varicella and Pneumocystis infection is 13%.
- Hepatic function: Actinomycin D and radiation may damage the liver, with an overall incidence rate of 10%. Hepatic venoocclusive disease (VOD) is a clinical syndrome of hepatotoxicity and consists of jaundice, ascites, hepatomegaly, and weight gain. The incidence rate is 8%. Patients younger than 1 year have double the incidence of VOD.
- Gonadal function: Chemotherapy may affect gonadal function in boys but rarely affects the function of ovaries. Abdominal irradiation may induce ovarian failure if ovaries were in the target field.
- Musculoskeletal function: Clinical rickets is possible due to renal tubular Fanconi syndrome caused by drugs that are too cytotoxic. Skeletal sequelae of radiation, including scoliosis or kyphosis, result from uneven growth when the radiation was unilaterally targeted to the vertebral bodies and the dose was higher than 2000 rads.
- Second malignant neoplasm: These may result from inherited disposition and treatment, bone tumors, breast cancer, and thyroid cancer. The rate after a medium follow-up of 15 years is 1.6%, which is 5 times the expected rate. Second malignant neoplasm can possibly be limited by limiting the intensive chemotherapy and radiotherapy and reserving the intensive treatment regimens only for the high stages and the cases with unfavorable histology.
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| Workup: Wilms Tumor |
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| Follow-up: Wilms Tumor |
| References |
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References
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Metzger ML, Dome JS. Current therapy for Wilms' tumor. Oncologist. Nov-Dec 2005;10(10):815-26. [Medline].
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Further Reading
Keywords
Wilms tumor, nephroblastoma, WT, embryoma of the kidney, mixed tumor of the kidney, sporadic Wilms tumor, familial Wilms tumor, bilateral Wilms tumor, Beckwith-Wiedemann syndrome, hemihypertrophy, congenital aniridia, WAGR syndrome, Denys-Drash syndrome, trisomy 18 mutation, teratoid Wilms tumor
