Bilateral Wilms tumor

Preoperative three-dimensional modelling and virtual reality planning aids nephron sparing surgery in a child with bilateral Wilms tumour

Bilateral Wilms tumour (BWT) is a surgically challenging condition. Virtual reality (VR) reconstruction aids surgeons to foresee the anatomy ahead of Nephron Sparing Surgery (NSS). Three-dimensional (3D) visualisation improves the anatomical orientation of surgeons performing NSS. We herewith report a case of BWT where VR planning and 3D printing were used to aid NSS. Conventional imaging is often found to be inadequate while assessing the tumour-organ-vascular anatomy. Advances like VR and 3D printing help surgeons plan better for complex surgeries like bilateral NSS. Next-generation extended reality tools will likely aid robotic-assisted precision NSS and improve patient outcomes.

Surgery in Bilateral Wilms Tumor-A Single-Center Experience

The treatment of bilateral Wilms tumors (BWT) involves curing the cancer, preserving long-term renal function, and maintaining a good quality of life. Established methods for achieving these goals include preoperative chemotherapy and nephron-sparing surgery (NSS). This study aimed to evaluate the experience of a single institution in treating patients with BWT. We analyzed cases of BWT treated at the Pediatric Oncology Institute-GRAACC-Federal University of São Paulo over a period of 35 years. Bleeding control was performed with manual compression of the renal parenchyma. Thirty-three patients were included in the study. Thirty cases were synchronous tumors. The mean age at diagnosis was 30.4 months (±22 m) and 66.7% were girls. The median follow-up period was 83 months. Neoadjuvant chemotherapy was the primary approach in most patients (87.9%), with a simultaneous upfront surgical approach performed in 84.8%. Most patients underwent bilateral NSS (70.4%). There were no early complications in this series, but 39.4% had clinical complications. The five-year survival rate was 76%. Therefore, it is clear that the surgical approach to BWT plays a crucial role in achieving good outcomes. However, it is difficult to standardize surgical techniques and technology may have the potential to enhance safety.

Evaluation of the nephron-sparing surgery formula in Wilms tumors

AIM

Definitions of nephron-sparing surgery (NSS) procedures in Wilms tumor (WT) are not clear. The new UMBRELLA protocol offers a formula (NSS(X)-SRM(n)-PRM(n)-RRP(n%)) to better define the different NSS parameters. We aimed to assess the advantages and limits of this new formula.

METHODS

This retrospective monocentric study included patients operated by NSS for WT from 1975 to 2018. We reviewed the medical records and applied the NSS formula to all included patients.

RESULTS

Eighty kidneys were operated on 56 patients at a mean age of 19.2 months (4 days-7.5 years), with 49 partial nephrectomies and 31 tumorectomies. The assessment of the surgical resection margins (SRM) showed a doubt in six cases and one tumor breach. An intact pseudocapsule along the resection margin with no renal parenchyma was found in four cases at pathological resection margins (PRM) assessment, whereas a tumor breach was described in seven cases. Among the six patients with a surgical doubt, only one had a pathological stage III. There were no surgical doubts in the seven patients with tumor breach at pathology. At a mean follow-up of eight years (15 days-28.6 years), eight patients had elevated blood pressure levels. Ten had proteinuria. These two parameters were significantly increased in patients with a remaining renal parenchyma (RRP) of less than half of the initial total renal parenchyma. The serum creatinine level was normal for all except two patients.

CONCLUSION

The new NSS formula described all the crucial elements of NSS. RRP seemed essential for the evaluation of long-term renal function.

Management of bilateral Wilms' tumour: A case report

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Wilms’ tumor is the most prevalent kidney tumor, accounting for 6% of all pediatric malignancies, 5–7% being bilateral case.

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Cases about a 19-month-old boy diagnosed as stage V Wilms tumor based on SIOP and NWTSG classification.

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Neoadjuvant chemotherapy regimen followed by the right partial, left radical nephrectomy, and adjuvant radiotherapy.

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No specific guideline on follow-up and imaging timing; we do regular follow-up every 12 months and periodic MRI imaging.

Introduction

Wilms’ tumour remains the most common renal tumour in children (6% of all pediatric malignancies) and present as one of the most challenging tasks for paediatric urologists as its management requires an advanced procedure. The ultimate goal in these cases is to preserve as much renal parenchyma as possible whilst still achieving complete tumour resection.

Presentation of case

Here we present a six year follow up report of a bilateral Wilms’ tumour case in a 19-months old boy. This patient underwent neoadjuvant chemotherapy regimen, followed by right partial nephrectomy and left radical nephrectomy. Adjuvant radiotherapy was performed following the surgery. Follow-up imaging 5 months afterward revealed a firmly heterogeneous cystic lesion consist of fat and calcification at the upper pole of the right kidney, none of which created any problem for the patient. MRI was later performed on the 19^th month after the surgery, showing marked decrease in the size of the cyst.

Discussion

According to SIOP and NWTSG classification, the patient presented as stage V of the disease. The patient was on neoadjuvant chemotherapy (Regimen I) as recommended by NWTSG. This strategy was shown to be effective, as the tumour on the left kidney was reduced to less than 70% of the initial size. A routine follow-up using chest x-ray, abdominal ultrasonography (USG), and contrast studies such as MRI and MSCT scan, was performed in our reports.

Conclusion

From our experience, the combination of neo-adjuvant chemotherapy, renal salvage surgery and adjuvant radiotherapy is a feasible, safe and effective option for bilateral Wilms’ tumour cases.

Complications Following Nephron-Sparing Surgery for Wilms Tumor

PURPOSE

Because of the increasing use of nephron-sparing surgery (NSS) in bilateral Wilms tumor, we sought to review the early postoperative complications associated with NSS.

METHODS

A retrospective review of patients who underwent NSS at our institution from 2000 to 2017 was performed. For comparison, a cohort of patients who underwent radical nephrectomy (RN) was also reviewed. Early (30-day) postoperative complications and oncologic outcomes were assessed.

RESULTS

Fifty-five patients underwent either bilateral (46) NSS or unilateral (9) NSS owing to prior resection or congenital solitary kidney. Fifty-four patients who underwent unilateral RN were also evaluated. Twenty NSS patients (36.4%) experienced 21 postoperative complications, including prolonged urine leak (9), infection (8), transient renal insufficiency (1), and intussusception (3). Seven RN patients (13.0%) experienced surgical complications, including infection (4) and intussusception (3). Average intraoperative blood loss was significantly greater in NSS as compared to RN (483.51 ± 337.92 mL and 278.15 mL ± 390.25, respectively, p < 0.001), as was the incidence of positive tumor resection margins (20 [36.4%] and 12 [22.2%], respectively, (p = 0.037).

CONCLUSIONS

In our experience, prolonged urine leak, intraoperative blood loss, and positive margins were more frequent in patients undergoing NSS as compared to RN. However, the complications were successfully managed, suggesting that an aggressive approach to NSS in patients with bilateral Wilms tumor is safe and appropriate.

LEVEL OF EVIDENCE

Level III TYPE OF STUDY: Treatment study.

Evaluation of diagnostic utility of imprint cytology in paediatric renal tumours with special references to Ki 67 proliferative marker

BACKGROUND:

Pediatric renal neoplasms comprise about 7%–8% of all neoplasms in children. Wilms tumour (WT) is the most common among pediatric renal tumours.

AIMS AND OBJECTIVES:

The study was undertaken to study the epidemiological occurrence of pediatric renal tumours in a tertiary care hospital and to ascertain the validity and reliability of touch smear imprint cytology in intraoperative diagnosis of renal tumours and correlate with subsequent histopathological diagnosis and to assess the expression of proliferation marker Ki-67 in different components and stages of WT.

MATERIALS AND METHODS:

It was a single-institution-based prospective and observational study, conducted for 2 years (from October 2013 to September 2015) in the department of pathology at our hospital. A total of fifty cases were enrolled in this study, all were below 15 years of age.

RESULTS:

Imprint cytology showed sensitivity, specificity, and diagnostic accuracy of 83%, 98%, and 95.74%, respectively, in diagnosing benign and malignant renal tumours. There was statistically significant correlation of imprint cytology with confirmatory histopathological examination of excision specimen (P < 0.001). Immunohistochemical analysis of Ki-67 was done in all WT cases. Epithelial component had higher proliferative index than blastemal component with P = 0.0082, which was highly statistically significant.

CONCLUSION:

Imprint cytology is found to be a less expensive, simple, and rapid method, which can be used as an adjunct to histopathology. Correlation between proliferation index as measured with Ki-67 antibody and tumour stage was found. Ki-67 is thus a relevant marker for assessing the proliferative activity.

Management of bilateral Wilms tumours

Wilms tumour is named after Max Wilms. It is an embryonal tumour derived from the metanephros. It is the commonest childhood renal tumour and the third commonest paediatric malignancy. Synchronous bilateral Wilms tumours (BWT) represent 4-7% of all Wilms tumours (WT) and present at a younger age than unilateral Wilms tumours. At least 10% of synchronous BWTs have unfavourable histology, and up to 22% are associated with genitourinary abnormalities, aniridia, WAGR syndrome, Denys-Drash syndrome, hemihypertrophy, or one of the other overgrowth syndromes. The long-term disease-free survival rate for patients with unilateral WT is approaching 90%, and is around 70% for those with metastatic disease. For both synchronous and metachronous Wilms tumours the prognosis is less favourable with reported cure rates approaching 80% in the best centres and lower in resource poor settings. There is potential for a reduced quality of life due to renal insufficiency and the possible need for renal transplantation. The major clinical challenge in BWTs is preservation of functioning renal tissue using nephron-sparing surgical techniques, while achieving cure with minimum therapy-related morbidity. Mortality is generally associated with progressive disease of anaplastic tumours. Chemotherapy followed by nephron-sparing surgery has been able, in most cases, to eradicate the tumour while preserving renal function. Radiotherapy has largely been avoided because of fears of long-term radiation injury to the residual functioning renal mass. Patient selection, appropriate pre- and post-operative chemotherapy and skilled surgical techniques all contribute to excellent outcomes where these are achievable.

Management of bilateral Wilms tumours

Wilms tumour is named after Max Wilms. It is an embryonal tumour derived from the metanephros. It is the commonest childhood renal tumour and the third commonest paediatric malignancy. Synchronous bilateral Wilms tumours (BWT) represent 4-7% of all Wilms tumours (WT) and present at a younger age than unilateral Wilms tumours. At least 10% of synchronous BWTs have unfavourable histology, and up to 22% are associated with genitourinary abnormalities, aniridia, WAGR syndrome, Denys-Drash Syndrome, hemihypertrophy, or one of the other overgrowth syndromes. The long-term disease-free survival (DFS) rate for patients with unilateral Wilms' tumours is approaching 90%, and is around 70% for those with metastatic disease. For both synchronous and metachronous Wilms tumours the prognosis is less favourable with reported cure rates approaching 80% in the best centres and lower in resource poor settings. There is potential for a reduced quality of life due to renal insufficiency and the possible need for renal transplantation. The major clinical challenge in BWTs is preservation of functioning renal tissue using nephron sparing surgical techniques, while achieving cure with minimum therapy-related morbidity. Mortality is generally associated with progressive disease of anaplastic tumours. Chemotherapy followed by nephron sparing surgery has been able, in most cases, to eradicate the tumour while preserving renal function. Radiotherapy has largely been avoided because of fears of long term radiation injury to the residual functioning renal mass. Patient selection, appropriate pre- and post-operative chemotherapy and skilled surgical techniques all contribute to excellent outcomes where these are achievable.

Management of Bilateral Wilms' Tumor: Our Experience

Management of bilateral Wilms' tumor is particularly challenging, considering the chances of recurrence and long-term renal function for affected patients. Aggressive surgical resection to prevent recurrence must be balanced with the desire to preserve renal function. We evaluated our experience in the management of bilateral Wilms' tumor stressing the challenges encountered in decision making and the role of nephron sparing surgery. We had four children presenting with bilateral Wilms' tumor. All of them were appropriately staged and given standard chemotherapy as per NWTS-5 guidelines. Tumors were considered to have a 'good' response to chemotherapy if sufficient tumor shrinkage was observed so that renal hilum was seen free of tumor and vice versa. Nephron-sparing surgery was considered in all and was performed when feasible, followed by completion adjuvant chemotherapy. All patients were followed up with serial ultrasound scans (3-6 monthly) and CECT abdomen (yearly once). Blood urea and serum creatinine, hypertension, and proteinuria were assessed during follow-up visits. All four children received neo-adjuvant chemotherapy as per NWTS-5 guidelines. The first child had poor response to chemotherapy and was considered for left radical and right partial nephrectomy. However, patient attenders refused any surgical intervention and the child was taken home. The second child had a 'good' response on left side and was planned for left partial and right radical nephroureterectomy based on pre-operative imaging analysis. However, intra-operatively, bilateral partial nephrectomy with good margins was feasible. The third child though, showed 'poor' response to pre-op chemotherapy and warranted bilateral nephroureterectomy, right partial and left radical nephroureterectomy was feasible. However, in the fourth child, we were not able to perform nephron sparing surgery and left nephroureterectomy with right tumor biopsy was done. Following this, child was started on 2nd-line chemotherapy, now awaiting right partial nephrectomy. The second child is on follow up for 1.5 years, doing well. However, the third child expired 1.5 years following surgery due to recurrence (lung metastasis). Management of bilateral Wilm's tumor is challenging and nephron-sparing surgery should be considered in all patients having bilateral Wilm's tumor with favorable histology, even if pre-operative imaging studies suggest that the lesions are unresectable.

Biomarkers for Wilms Tumor: A Systematic Review

PURPOSE

Wilms tumor is the most common childhood renal malignancy and the fourth most common childhood cancer. Many biomarkers have been studied but there has been no comprehensive summary. We systematically reviewed the literature on biomarkers in Wilms tumor to quantify the prognostic implications of the presence of individual tumor markers.

MATERIALS AND METHODS

We searched for English language studies from 1980 to 2015 performed in patients younger than 18 years with Wilms tumor and prognostic data. The protocol was conducted per PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) guidelines. Two reviewers abstracted data in duplicate using a standard evaluation form. We performed descriptive statistics, then calculated relative risks and 95% confidence intervals for markers appearing in multiple level II or III studies.

RESULTS

A total of 40 studies were included examining 32 biomarkers in 7,381 patients with Wilms tumor. Studies had a median of 61 patients, 24 biomarker positive patients per series and a median followup of 68.4 months. Median percentages of patients with stages 1, 2, 3, 4 and 5 tumors were 28.5%, 26.4%, 24.5%, 14.1% and 1.7%, respectively, and 10.2% had anaplasia. The strongest negative prognostic association was loss of heterozygosity at 11p15, with a risk of recurrence of 5.00, although loss of heterozygosity at 1p and gain of function at 1q were also strongly linked to increased recurrence (2.93 and 2.86, respectively).

CONCLUSIONS

Several tumor markers are associated with an increased risk of recurrence or a decreased risk of overall survival in patients with Wilms tumor. These data suggest targets for development of diagnostic tests and potential therapies.

A Rare Coexistence of Bilateral Congenital Wilms Tumor with Ductal Plate Malformation at Autopsy

Congenital Wilms tumor is a tumor of childhood. Here we present an unusual case of bilateral congenital Wilms tumor with associated ductal plate malformation. In addition, there was also associated oligohydramnios, pulmonary hypoplasia, and multiple skeletal anomalies in this index case. Although various syndromic associations of Wilms tumor are well described in the literature, an association of congenital Wilms tumor with ductal plate malformation, polysplenia, and skeletal malformations is not reported. We believe that this is the first reported case of such an association.

Overall Survival and Renal Function of Patients With Synchronous Bilateral Wilms Tumor Undergoing Surgery at a Single Institution

OBJECTIVES

Wilms tumor is the most common renal cancer in children. Approximately 5% of children with Wilms tumor present with disease in both kidneys. The treatment challenge is to achieve a high cure rate while maintaining long-term renal function. We retrospectively reviewed our institutional experience with nephron sparing surgery (NSS) in patients with synchronous bilateral Wilms tumor (BWT) operated on between 2001 and 2014.

METHODS

Imaging studies, surgical approach, adjuvant therapy, and pathology reports were reviewed. Outcomes evaluated included surgical complications, tumor recurrence, patient survival, and renal function, as assessed by estimated glomerular filtration rate.

RESULTS

A total of 42 patients with BWT were identified: 39 (92.9%) patients underwent bilateral NSS; only 3 patients (7.1%) underwent unilateral nephrectomy with contralateral NSS. Postoperative complications included prolonged urine leak (10), infection (6), intussusception (2), and transient renal insufficiency (1). Three patients required early (within 4 months) repeat of NSS for residual tumor. In the long-term, 7 (16.7%) patients had local tumor recurrence (managed with repeat NSS in 6 and completion nephrectomy in 1) and 3 had an episode of intestinal obstruction requiring surgical intervention. Overall survival was 85.7% (mean follow-up, 4.1 years). Of the 6 patients who died, 5 had diffuse anaplastic histology. All of the patients had an estimated glomerular filtration rate more than 60 mL/min/1.73 m at the last follow-up; no patient developed end-stage renal disease.

CONCLUSIONS

In patients with synchronous, BWT, bilateral NSS is safe and almost always feasible, thereby preserving maximal renal parenchyma. With this approach, survival was excellent, as was maintenance of the renal function.

Nephron-sparing surgery for Wilms tumor: A systematic review

INTRODUCTION

Radical nephrectomy (RN, or total nephrectomy) is the current gold-standard surgical treatment for children with Wilms tumors (WT). However, nephron-sparing surgery (NSS, or partial nephrectomy) has recently been gaining increasing attention. The objective of this systematic review is to compare the effectiveness of NSS as compared with RN for the treatment of children with WT.

METHODS

We searched the Cochrane Controlled Trials Register, clinicaltrials.gov, MEDLINE, EMBASE, Google Scholar, and recently presented meeting abstracts for reports in English. The bibliographies of included studies were then hand-searched for any missed articles. The protocol was prospectively registered. Manuscripts were assessed and data abstracted in duplicate with differences resolved by the senior author. Owing to high heterogeneity among the final included studies, only a qualitative systematic review was performed; no formal meta-analysis was undertaken.

RESULTS

We identified 694 articles, 118 of which were selected for full-text review and 66 of which were included in the final analysis. Most studies were single- or multi-institution retrospective case series (60, 91%), with a small number of prospective cohort studies (6, 9%) and 1 administrative database analysis. Most studies were from Europe (27, 41%) or North America (21, 32%). Nearly half (32, 48%) of studies those were included were dated from 2010 or later. In total, data on 4,002 patients were included, of whom 1,040 (26%) underwent NSS and 2,962 (74%) underwent NSS. Reported rupture rates were similar between RN and NSS (13% vs. 7%), as were recurrence rates (12% vs. 11%) and survival rates (85% vs. 88%). However, these comparisons are limited by inherent biases in the design and reporting of most included studies.

CONCLUSIONS

Most contemporary studies reporting the use of NSS in children with WT report similar long-term outcomes to RN. However, most existing studies are limited by their small numbers, inconsistent reporting, and methodological biases. There are significant opportunities for future research on the use of NSS in children with WT, including issues related to surgical quality, optimal technique, timing and duration of chemotherapy, and variation in the use of NSS among centers.

Bilateral Wilms tumors treated according to the Japan Wilms Tumor Study Group protocol

BACKGROUND

The introduction of multimodal therapy has improved the survival rate of bilateral Wilms tumors (BWT); however, the results are still not satisfactory in terms of the renal preservation. To establish a new treatment strategy for BWT, we reviewed the results of the cases registered in the Japan Wilms Tumor Study Group (JWiTS).

PROCEDURE

This analysis concerned patients with synchronous BWT registered in the JWiTS between 1996 and 2011. In these patients, the management of BWT included initial tumor resection or biopsy followed by chemotherapy. The details of the treatments and outcomes were analyzed.

RESULTS

Among the 355 cases registered in the JWiTS database, 31 (8.7%) had BWT. They were 16 males and 15 females with a mean age of 15.5 months. Preoperative chemotherapy was performed in 24 cases. Bilateral nephron-sparing surgery (NSS) was achieved in 10 of 28 cases (36%). All of the cases were of favorable nephroblastoma without anaplasia, and a WT1 mutation was detected in 21 of the 27 cases (78%) examined. The 5-year overall survival was 92.6%; however, 10 children (40%) developed impaired renal function and three of them developed renal failure.

CONCLUSIONS

The long-term survival rates for patients with synchronous BWT have improved. However, more than half of patients receive nephrectomy. The protocol should be changed to improve the rate of preservation of the renal parenchyma. Preoperative chemotherapy should be performed to shrink the tumors in every case, and subsequent NSS should be carried out after a central imaging evaluation.

Synchronous bilateral Wilms tumor: a report from the Associazione Italiana Ematologia Oncologia Pediatrica (AIEOP)

BACKGROUND

The optimal management of bilateral Wilms tumor (BWT) is challenging, and their survival is lower than for unilateral tumors. This report discusses a large series of BWTs treated in Italy in the last 2 decades.

METHODS

This analysis concerns patients with synchronous BWT registered at Associazione Italiana Ematologia Oncologia Pediatrica (AIEOP) centers between 1990 and 2011; details on their treatment and outcome are presented and discussed.

RESULTS

Ninety BWTs were registered in the AIEOP Wilms tumor database. Preoperative chemotherapy was given for a median 12 weeks before definitive tumor resection was attempted. Forty-eight percent of the patients had preservation of bilateral renal parenchyma. The proportion of bilateral nephron-sparing surgeries was not higher in the 37 patients initially given doxorubicin/vincristine/actinomycin D (32%) than in the 43 children receiving vincristine/actinomycin D alone (58%). The 4-year disease-free survival rate was 66.5% ± 5% and overall survival was 80% ± 5% for the cohort as a whole. The 4-year disease-free survival (overall survival) for 18 children with diffuse anaplasia or postchemotherapy blastemal-type tumors was 51% ± 13% (62% ± 13%), as opposed to 72% ± 3% (88% ± 4%) for 68 children with a favorable histology (log-rank P = .04 [P = .007]).

CONCLUSIONS

These results provide further evidence that the optimal duration and choice of drugs for preoperative chemotherapy remain an open question. Outcome remained significantly worse for BWT than for unilateral Wilms tumor. To enable the conservative treatment of as many affected kidneys as possible, only centers with experience in BWT should manage such cases.

Bilateral Wilms tumors (WT) treated with the SIOP 93 protocol in France: epidemiological survey and patient outcome

BACKGROUND

The treatment of bilateral Wilms tumors (WT) requires multimodality therapy with individualized decision to ensure cure while preserving as much renal parenchyma as possible.

PROCEDURE

We analyzed the clinical records of 49 children with bilateral WT treated in France between 1993 and 2001, according to the SIOP-93 guidelines (individual treatment program: Treatment was continued as long as there was imaging evidence of tumor regression). Pathology reports, duration of preoperative chemotherapy and surgical records were also reviewed. Overall Survival (OS) and Event-Free Survival (EFS) rates were studied and relationships between possible prognostic factors and survival were assessed.

RESULTS

Imaging studies revealed bilateral involvement in 98% of the cases. Whatever the response to preoperative chemotherapy, the mean duration of neoadjuvant chemotherapy was 80 days (Q1-Q3: 47-89 days). Forty-eight children underwent nephron sparing surgery (NSS) at least for one kidney and 19 for both. Five-year EFS and OS rates were, respectively, 83.4 and 89.5%. Only the most advanced stages were shown to affect OS (P = 0.03). At study endpoint, end-stage renal disease (ESRD) was reported in seven children, associated with a predisposing phenotype in three.

CONCLUSIONS

Results of this study demonstrate a favorable outcome of patients with bilateral WT receiving an individual treatment program. With a tailored approach to treatment according to the tumor response, 77% of our patients were operated before the third month of preoperative chemotherapy. In spite of good survival, 14% of our patients have ESRD.

Bilateral Wilms' tumor: Mansoura multi-centers 15 years experience

Purpose. Bilateral Wilms' tumor (WT) is a challenge. Aggressive surgical resection is needed to prevent recurrence. We revised the clinico-epidemiological criteria of bilateral WT patients in our locality and relation to outcome.

Subjects and methods. 462 WT patients were registered in three medical centers at Mansoura, Egypt. Twenty five patients had bilateral WT whose medical records were revised for all clinico-epidemiologic data plus treatment details, toxicity, and outcome.

Results. The mean age was 34.5 months; 64% of cases were female. Abdominal mass was the commonest presentation (72%). Congenital anomalies were reported in two cases (one case showed hemihypertrophy and the other showed aniridia). About 60% had favorable pathology. Nineteen cases had synchronous bilateral WT (76%) and the remaining (six cases) had metachronous tumors. For the synchronous cases, the response rate to preoperative chemotherapy was 79% and nephron sparing surgery for the least involved kidney was possible in all. Survival rate was 74%. Metachronous tumor management included nephrectomy followed by chemotherapy for the initially diagnosed tumors. However, nephron sparing surgery of the contralateral tumors following preoperative chemotherapy was possible in two cases and the survival rate was 33%. No renal failure or any therapy-related complications were reported.

Conclusions. Bilateral WT is predominantly synchronous with favorable histology, with female predilection and possibly congenital anomalies. Preoperative chemotherapy followed by nephron sparing surgery has a favorable outcome with preserved renal function especially in patients with synchronous WT. Response to preoperative chemotherapy had a statistically significant prognostic impact.

The management of synchronous bilateral Wilms tumor: a report from the National Wilms Tumor Study Group

OBJECTIVE

To provide guidelines for future trials, we reviewed the outcomes of children with synchronous bilateral Wilms tumors (BWT) treated on National Wilms Tumor Study-4 (NWTS-4).

METHODS

NWTS-4 enrolled 3335 patients including 188 patients with BWT (5.6%). Treatment and outcome data were collected.

RESULTS

Among 188 BWT patients registered with NWTS-4, 195 kidneys in 123 patients had initial open biopsy, 44 kidneys in 31 patients had needle biopsies. Although pre-resection chemotherapy was recommended, 87 kidneys in 83 patients were managed with primary resection: Complete nephrectomy 48 in 48 patients, 31 partial/wedge nephrectomies in 27 patients, enucleations 8 in 8 patients. No initial surgery was performed in 45 kidneys in 43 patients, 5 kidneys in 3 patients not coded. Anaplasia was diagnosed after completion of the initial course of chemotherapy in 14 patients (initial surgical procedure: 9 open biopsies, 4 needle biopsies, 1 partial nephrectomy). The average number of days from the start of chemotherapy to diagnosis of anaplasia was 390 (range 44-1925 days). Relapse or progression of disease occurred in 54 children. End stage renal failure occurred in 23 children, 6 of whom had bilateral nephrectomies. The 8 year event free survival for BWT with favorable histology was 74%, and overall survival was 89%; whereas the event free survival for BWT with unfavorable histology was 40%, overall survival was 45%.

CONCLUSION

The current analysis of patients with BWT treated on NWTS-4 shows that preservation of renal parenchyma is possible in many patients after initial preoperative chemotherapy. The incidence of end-stage renal disease remains significantly higher in children with BWT. Future studies are warranted to address the need for earlier biopsy in nonresponsive tumors and earlier definitive surgery to recognize unfavorable histology in these high-risk patients.

Bilateral Wilms' tumors: single-center experience with 22 cases and literature review

OBJECTIVES

Bilateral Wilms' tumors represent a therapeutic challenge. The primary aim of management is eradication of the neoplasm and preservation of renal function. We present our experience in the management of such cases in a single-center experience.

METHODS

This was a retrospective study of 22 patients with histologically proven bilateral nephroblastoma who were treated from 1993 to 2008 at our center. Of the 22 patients, 12 were girls and 10 were boys, with a median age of 3 years (range 1-9); 19 had a synchronous presentation and 3 a metachronous presentation. Of the 22 patients, 6 underwent initial surgical resection followed by chemotherapy and 16 underwent initial biopsy and preoperative chemotherapy. The final oncologic and renal outcomes were assessed.

RESULTS

The median follow-up period was 3 years (range 1-11). Of the 22 patients, 8 died, for an overall survival rate of 63.5%. The survival for the initial chemotherapy and initial surgery groups was essentially similar. Of all the variables studied, unfavorable histologic findings had a significant negative effect on survival. Of the 5 patients with unfavorable histologic findings, 4 died during the follow-up period. The median volume of preserved renal parenchyma was 40%. All patients had good renal function during follow-up, except for 1 patient who had undergone bilateral nephrectomy.

CONCLUSIONS

Bilateral Wilms' tumors impose 2 conflicting issues: elimination of the pathology and preservation of the renal function. Currently, treatment regimens involving initial chemotherapy followed by conservative surgery can achieve these goals in an important proportion of patients.

Pediatric urologic oncology: organ-sparing surgery in kidney and testis

Technological advances in imaging as well as increased knowledge of tumor-specific biology have promoted the role of organ-sparing approaches to pediatric renal and testicular tumors. Application of these techniques continues to evolve as data on long-term follow-up become available and as protocol-guided investigation provides answers to therapeutic outcomes of these approaches. Optimally, organ-sparing surgery will continue to provide increased potential for preservation of both renal function and fertility.

Outcome of pediatric renal tumor treated using the Japan Wilms Tumor Study-1 (JWiTS-1) protocol: a report from the JWiTS group

PURPOSE

In 1996, the Japan Wilms Tumor Study (JWiTS) group was founded to elucidate the efficacy and safety of the regimen established by the National Wilms Tumor Study (NWTS) group in the USA, and a multicenter cooperative study (JWiTS-1) was started in Japan. This report reviews the results of JWiTS-1.

METHODS

A total of 307 patients with malignant renal tumor were enrolled in the JWiTS-1 study between 1996 and 2005. Central pathological diagnosis and follow-up data were available in 210 cases. The protocol regimens were similar to the NWTS-5 regimens. Clinical stage was classified according to the Japanese Staging System.

RESULTS

Five-year overall survival (OS) rate was 91.1% for nephroblastoma, 72.9% for clear cell sarcoma of the kidney (CCSK), and 22.2% for rhabdoid tumor of the kidney (RTK). In the nephroblastoma patients, 5-year OS was 90.5% for stage I disease, 92.2% for stage II, 90.9% for stage III, 86.7% for stage IV, and 78.7% for stage V.

CONCLUSIONS

The OS of patients in the JWiTS-1 study were comparable with the results of other multicenter studies in the USA and Europe. The outcome for patients with nephroblastoma and CCSK was fair. In contrast, the cure rate for those with RTK was not satisfactory. New treatment strategies are needed for patients with RTK.

Bilateral Wilms' tumor with anaplasia: lessons from the National Wilms' Tumor Study

PURPOSE

The purpose of this study was to evaluate whether initial diagnostic technique influenced the ability to identify anaplastic histology, to determine the time interval to diagnosis of anaplasia, and to delineate the incidence of discordant pathology in bilateral Wilms' tumor. We hypothesized that delay in diagnosis of anaplasia could affect time to appropriate surgery and intensive multimodality therapy.

METHODS

One hundred eight-nine children were enrolled in the fourth National Wilms' Tumor Study with synchronous bilateral tumors, 27 of whom were eventually shown to have anaplastic histology. Initial diagnostic technique, time interval to diagnosis of anaplasia, and the incidence of discordant pathology were determined.

RESULTS

Anaplasia was identified in 0 of 7 tumors by core needle biopsy, 3 of 9 tumors by open wedge biopsy, and in 7 of 9 cases by partial or complete nephrectomy. The mean duration of first chemotherapy regimen (DD or EE) was 20, 39, and 36 weeks, respectively, before anaplasia was identified at second surgery. Discordant pathology between bilateral tumors was identified on final tissue diagnosis in 20 patients. Only 4 patients had anaplastic tumors in both kidneys.

CONCLUSIONS

Core needle biopsy did not identify anaplasia in 7 of 7 children. Open biopsy or partial/complete nephrectomy identified anaplasia at initial diagnostic procedure in 10 of 18 children. Twenty of 24 patients at final tissue diagnosis had discordant pathology between the 2 kidneys. Earlier interval incisional biopsy or resection may identify anaplastic histology and limit the duration of chemotherapy targeted to favorable histology for children with bilateral Wilms' tumor and anaplasia.

Bilateral Wilms' tumors with progressive or nonresponsive disease

BACKGROUND

To provide guidelines for future cooperative group trials, we reviewed the outcomes of children with bilateral Wilms' tumors (BWTs) treated on National Wilms Tumor Study-4 (NWTS-4) who had progressive or nonresponsive disease (PNRD).

METHODS

NWTS-4 enrolled 3335 patients from August 1986 to September 1994 including 188 patients with BWT (5.6%). Treatment and outcome data were collected on patients with BWT. Treatment guidelines were outlined in the protocol, but patients were not on study.

RESULTS

Thirty-eight children with BWT had PNRD. Preoperative chemotherapy was given for a median of 7 months (range, 2-29 months) before definitive resection. After the initial chemotherapy regimen, 36 children went on to a second regimen, and of these, 21 children received a third regimen before resection. Eleven patients received irradiation to one or both kidneys. Pathology at resection revealed previously undiagnosed anaplasia in 3 patients (2 diffuse and 1 focal) treated for 14, 15, and 15 months before resection. A fourth patient developed a diffusely anaplastic tumor 13 months after therapy. Other pathological findings included rhabdomyomatous (4 patients) or differentiated stromal elements (10 patients) and complete necrosis (1 patient). Ten kidneys from 7 patients lacked biopsy at presentation or pathology review of those specimens.

CONCLUSIONS

BWT patients with PNRD received prolonged courses of chemotherapy. Early and sequential biopsies to establish the reason for failure to respond should be obtained. This will identify anaplastic tumors managed best by early nephrectomy and intensive chemotherapy and will also distinguish differentiated tumors that are best managed with early resection, but less intensive therapy after nephrectomy.

Current therapy for Wilms' tumor

Wilms' tumor was the first solid malignancy in which the value of adjuvant chemotherapy was established. Multimodality treatment has resulted in a significant improvement in outcome from approximately 30% in the 1930s to more than 85% in the modern era. Although the National Wilms' Tumor Study Group and the International Society of Pediatric Oncology differ philosophically regarding the merits of preoperative chemotherapy, outcomes of patients treated with either up-front nephrectomy or preoperative chemotherapy have been excellent. The goal of current clinical trials is to reduce therapy for children with low-risk tumors, thereby avoiding acute and long-term toxicities. At the same time, current clinical trials seek to augment therapy for patients with high-risk Wilms' tumor, including those with bilateral, anaplastic, and recurrent favorable histology tumors.

Bilateral Wilms' tumors: a single-center experience with 19 cases

BACKGROUND/PURPOSE

Bilateral Wilms' tumors present a therapeutic challenge, particularly with delay in presentation, when there is poor response to chemotherapy and when associated with nephroblastomatosis. The primary aim of management is eradication of neoplasm, while at the same time preserving of renal function.

METHODS

Nineteen bilateral Wilms' tumors were seen in our service between 1981 and 2003. This represented 10% of the 190 patients with Wilms' tumors seen during this period. There were 12 female and 7 male patients ranging in age from 7 months to 8 years. Fourteen had synchronous presentation, one of whom had liver metastasis at diagnosis. Of the 5 patients with metachronous tumors, 3 had their initial nephrectomies done elsewhere. Nephroblastomatosis was identified in 18 (95%) of the patients. Treatment was, in most cases, according to National Wilms Tumor Study Group protocols, with initial bilateral biopsy, neoadjuvant chemotherapy, and tumorectomy. Where indicated, nephrectomy (partial or complete) involved using ice dam topical cooling and vascular control, and in one case, bench surgery and extensive renal reconstruction with orthotopic autotransplantation. Revision tumorectomy was used on 3 occasions for recurrence in areas of nephroblastomatosis. There were 6 extrarenal relapses.

RESULTS

Ten patients are alive and free of disease 1 to 15 years after treatment, all with well preserved renal function (lowest recorded glomerular filtration rate was 85 mL/min per 1.73 m2). Nine have died (2 of unrelated disease), including 6 of the 7 with spread outside the kidney. All 3 with unfavorable histology are alive. Of the 5 with metachronous presentations, 4 are alive, as are 7 of 10 who presented in the last decade.

CONCLUSIONS

Appropriate chemotherapy and conservative nephron-sparing and innovative surgery can achieve good results with preservation of adequate renal function in nearly all cases. Nephroblastomatosis was an almost universal finding and requires close monitoring because Wilms' tumors developed in residual suspect areas. Revision surgery was effective. Unfavorable histology did not have a reduced survival in our series. Metastatic spread outside the kidney had a poor prognosis.

Nephroblastic Neoplasms

Nephroblastoma, or Wilms tumor, is a malignant embryonal neoplasm that is derived from nephrogenic blastemal cells, with variable recapitulation of renal embryogenesis. The pathogenesis of nephroblastoma is complex and has been linked to alterations of several genomic loci, including WT1, WT2, FWT1, and FWT2. Generally, nephroblastoma is composed of variable proportions of blastema, epithelium, and stroma, each of which may exhibit a wide spectrum of morphologic variations. Distinguishing nephroblastoma with favorable histology from tumors that exhibit anaplasia is an integral component of histologic assessment because of its prognostic and therapeutic implications. Nephrogenic rests and a special variant of nephroblastoma, cystic partially differentiated nephroblastoma, also are discussed.

Pediatric renal tumors: practical updates for the pathologist

Pediatric renal tumors were targeted by the National Wilms Tumor Study Group for 4 decades with extraordinary success. Within this historic context, this review provides a summary of the new Children's Oncology Group renal tumor protocols that will be opening in the very near future, focusing on their pathologic requirements. All renal tumors must first be registered on the Renal Tumor Classification and Banking Protocol, followed by registration on 1 of 4 primary therapeutic protocols based on histology, stage, and molecular analysis. This requires prompt submission of samples for molecular analysis and central pathologic review. Changes in staging criteria include classification of all tumor spillage as stage III, and requirement of regional lymph node evaluation for eligibility for stage I Wilms tumors (WTs) weighing less than 550 g in infants younger than 24 months and for stage I clear cell sarcoma. Patients with unilateral favorable histology WT with loss of heterozygosity for chromosomes 1p and 16q will receive more aggressive chemotherapy at each stage. Patients with bilateral WT and patients with diffuse hyperplastic perilobar nephroblastomatosis will be eligible for a novel therapeutic protocol requiring pathologic classification based on response of tumor to previous therapy. Stage I anaplastic WT will be targeted with more aggressive chemotherapy than in the past. For the first time, pediatric renal cell carcinoma will be eligible for a cooperative group protocol. All rhabdoid tumors outside the central nervous system will be eligible for a single protocol. In conclusion, these new protocols bring considerable change in their overall organization, in eligibility, and in therapy.

Renal function and outcome following salvage surgery for bilateral Wilms' tumor

PURPOSE

Maintaining adequate renal function without compromising cure in children with bilateral Wilms' tumor is surgically demanding and challenging. The aim of this study was to assess renal function and outcome in children treated in one institution for bilateral Wilms' disease by renal salvage procedures.

METHODS

This study is a retrospective review of all patients with histologically proven bilateral nephroblastoma who underwent a renal salvage procedure between November 1973 and June 2002. The median follow-up time was 52 months (range, 8 to 326 months).

RESULTS

Twenty-three patients were included in the study. The median age at diagnosis was 19 months (range, 5 to 65 months). Patients who presented before 1982 (n = 5) were treated surgically first followed by chemotherapy. The remainder (n = 18) received initial chemotherapy before the operation. Of the 46 kidneys, 18 had a nephrectomy. The remaining 28 underwent a renal salvage procedure. At follow-up, 19 patients had good renal function, 2 had satisfactory function, and 2 had renal failure. Seventeen of the 23 children are alive and tumor free at follow-up (74%). Four children died of distant metastases and 2 of renal failure. Local recurrence in the salvaged kidney was detected in 1 patient 12 years after surgery after the commencement of immunosuppression for renal transplantation.

CONCLUSIONS

These results confirm that renal salvage procedures, in combination with chemotherapy, are a safe and effective way of treating children with bilateral Wilms' disease. In addition, renal salvage surgery can maintain satisfactory renal function in the majority of these patients without an increased risk of local recurrence. When transplantation is required, the remaining native kidney should be removed to prevent tumor recurrence.

Controversies in the management of Wilms' tumor

Wilms' tumor is the most common malignant renal tumor of childhood; it represents 5% to 6% of childhood cancers in the United States. The survival rate of children with Wilms' tumor has improved dramatically, partly due to large multicenter studies conducted by the National Wilms' Tumor Study Group and the International Society of Pediatric Oncology. To ensure optimal patient outcome, the surgical management of these patients must be appropriate. Controversial issues in the management of Wilms' tumor include the value of preoperative chemotherapy; whether pre-resection biopsy is indicated and if so, how this is best performed; indications for partial nephrectomy; the treatment of low-risk patients with surgery only; and the reliability of preoperative imaging to assess the contralateral kidney.

Wilms' tumor. Overview of National Wilms' Tumor Study Group results

Since its inception in 1969, the NWTSG has performed successful studies that are now the model for the management of pediatric malignancies. Future studies may use genetic markers to stratify high-risk patients beyond the traditional staging system. Therapy will continue to be evaluated to determine the minimal therapy necessary to achieve the best outcome for children with Wilms' tumor.

Wilms' tumor. Surgical considerations and controversies

Although the therapeutic objectives for Wilms' tumor are to maximize outcomes and minimize treatment morbidity, there are some controversial issues related to different therapeutic protocols. In this article, the authors address some of the issues such as the roles of tumor biopsy, preoperative chemotherapy, contralateral exploration, and partial nephrectomy.

Childhood tumors

Pediatric solid tumors represent a distinct set of malignancies of embryonal origin whose incidence peaks in the first years of life. Specific genetic anomalies with pathogenic significance, which have helped to define the diagnosis better and to improve the prognosis of children with these tumors, recently have been discovered. Survival of children with solid tumors also has improved significantly because of effective multidisciplinary care, which, in this case, always involves chemotherapy and surgery. These favorable results require that children with these diseases are referred and treated at institutions that have multidisciplinary teams and the infrastructure and expertise for caring for these children. Diagnostic and therapeutic principles for the most common childhood solid tumors are discussed in this article, with an emphasis on surgical procedures.

Nephron-sparing surgery in synchronous bilateral Wilms' tumors

BACKGROUND

Synchronous bilateral Wilms' tumor is rare and experience with renal salvage procedures and their limitations accumulates slowly at single institutions. The authors analyzed whether their growing experience with atypical renal resections and awareness of nephroblastomatosis had influenced the outcome of surgical procedures.

METHODS

Retrospective analysis of patients treated from 1977 to 1995 was performed. Surgical reports, clinical sheets, and follow-up data were evaluated. All pathology slides were reviewed for histological classification and presence of nephroblastomatosis. Renal function was evaluated pre- and postoperatively and at final follow-up.

RESULTS

Fourteen patients were treated. Two to 20 years after surgery, 13 patients are alive, and none has had renal failure. Five patients had unilateral nephrectomies, and a renal salvage procedure was performed on 22 kidneys. One patient with an anaplastic bilateral Wilms' tumor died of tumor progress 1 year after surgery. Several kidneys, which would have been sacrificed by application of traditional criteria, could be salvaged by atypical and unconventional tumor resections and by superficial dissection and enucleation of supposed nephroblastomatosis. Nephrectomy appeared unavoidable with hilar invasion by tumor.

CONCLUSION

Atypical resections of localized lesions and superficial dissections of suspected nephroblastomatosis appeared as valid surgical treatment options for patients who would otherwise have been candidates for nephrectomy. In the case of hilar tumor invasion, however, nephrectomy seems unavoidable.

Pediatric renal tumors

A broad spectrum of renal tumors occurs in infants and children ranging from the benign cystic nephroma to the extremely aggressive malignant rhabdoid tumor of the kidney. A thorough understanding of these tumors is crucial to the optimal diagnosis and management of children with renal masses. The common renal tumors in infants and children are discussed and an orderly method for their evaluation is presented. Recent developments in the molecular biology of Wilms' tumor are outlined to provide insight into the origin of this tumor.

Bilateral Wilms' tumor: a clinicopathologic review

Bilateral Wilms' tumor occurs at a younger age than unilateral disease. While it generally has a good prognosis, it presents a therapeutic dilemma to balance curative surgical resection with preservation of renal tissue. A 15 year review of bilateral Wilms' tumors diagnosed at Princess Margaret Hospital was undertaken. Of 46 Wilms' tumor cases, eight were designated bilateral by diagnostic imaging (median age 1.1 years compared with 3.5 years for unilateral tumors). The surgical management entailed primary nephrectomy with contralateral biopsy in two patients, and bilateral biopsy and delayed resection in all remaining surviving patients (one patient died of perioperative complications). Seven patients had localized disease (stage I/II) and the six surviving patients received chemotherapy with vincristine and actinomycin; no patient received radiotherapy. All are alive and well (median follow-up 5.1 years). The remaining patient presented with pulmonary metastases and died of disease progression. Pathologic review revealed that four patients had truly bilateral disease demonstrable by histology, three had unilateral Wilms' tumor with contralateral nephrogenic rests, and in one patient the biopsies of the contralateral kidney showed neither tumor nor nephrogenic rests. In most cases pathological material was subject to external review. Follow-up demonstrates excellent renal function with compensatory hypertrophy in the remaining renal tissue. Conservative surgery and simple out-patient based, low toxicity chemotherapy is curative in most patients.

Conservative surgical management of bilateral Wilms tumor: results of the United Kingdom Children's Cancer Study Group

PURPOSE

Bilateral Wilms tumor presents the clinician with a treatment dilemma. Since 1980 most centers of the United Kingdom Children's Cancer Study Group have used a conservative surgical approach with initial biopsy followed by chemotherapy and delayed surgical resection. We assess the outcome of this treatment approach in terms of survival, and preservation of renal mass and function.

MATERIALS AND METHODS

We retrospectively analyzed the records of 71 children with bilateral Wilms tumor diagnosed between 1980 to 1995 at 17 United Kingdom Children's Cancer Study Group centers. In 57 patients conservative surgical treatment with initial biopsy was followed by chemotherapy and delayed tumor resection, while 13 underwent initial surgical resection followed by chemotherapy. One patient was excluded from study because the lesion in 1 kidney proved to be a benign cyst. Mean followup was 6 years (range 1 to 15). The percentage of renal tissue involved with tumor and preserved was estimated, and renal function at the last followup was recorded.

RESULTS

Overall survival was 69% with similar survival in the conservatively treated and initial surgical resection groups. At the last followup renal function was normal in 80% of the patients in each group. Mean preserved renal mass was 45 and 35% in the conservatively treated and initial resection groups, respectively, with a trend toward better preservation in those treated conservatively. Bilateral Wilms tumor with an unfavorable histology was associated with a poor prognosis.

CONCLUSIONS

Conservative surgical treatment of favorable histology bilateral Wilms tumor may improve the preservation of renal mass and function without impairing patient survival.

Misleading leads: Wilms tumor with a metachronous lesion appearing in the remaining kidney

Medullary dysplasia may be present in the kidneys of children with the Beckwith-Wiedemann Syndrome (BWS). This is usually visible only at the microscopic level, but superimposed pyelonephritis in a child with the BWS led to gross changes that produced a filling defect on CT scanning of the remaining kidney. The finding could have been misinterpreted as a metachronous wilms tumor.

Long-term renal function in patients with irradiated bilateral Wilms tumor. National Wilms' Tumor Study Group

The treatment of bilateral Wilms tumor (BWT) involves a multidisciplinary approach including surgery, chemotherapy, and radiation therapy. The long-term renal function in patients receiving all three treatment modalities has not been evaluated. Long-term renal function was evaluated in 81 children with synchronous BWT who received radiation therapy as part of their treatment. Renal function was assessed by measuring blood urea nitrogen (BUN) and serum creatinine (Cr). The normal range for the BUN was defined as 10-24 mg/dl, and the Cr was considered normal at levels of <1.5 mg/dl. Moderate elevations were defined as a BUN of 25-50 mg/dl and/or a Cr of 1.6-2.5 mg/dl and marked elevations as a BUN of >50 mg/dl and/or a Cr of >2.5 mg/dl. BUN and Cr levels were measured prior to treatment and at the following intervals: 6 months after treatment, 1 year after treatment, 2 years after treatment, and at last follow-up. Any elevation during the posttreatment follow-up period was considered abnormal. A total of 28 children (34.6%) had elevated BUN and/or Cr levels, and 18 had moderate and 10 had marked renal insufficiency. No dose-response relationship was established when comparing the radiation doses of those with elevated values to those with normal values. The renal complication rate was moderate, and other factors including surgery, extent and nature of chemotherapy, and recurrent tumor must also be taken into account. The elevations present in several children could be attributed to tumor recurrence and in one case to gentamicin toxicity. The management of children with BWT should consider all of these risks, and attempts to preserve renal parenchyma are warranted.

A technique for the use of afterloading 137Cs brachytherapy in renal-sparing irradiation of bilateral Wilms tumor

PURPOSE

To describe a renal sparing brachytherapy technique for treating patients with bilateral Wilms tumor who have limited residual tumor measuring 2 cm or less after initial chemotherapy.

METHODS AND MATERIALS

A technique for using brachytherapy in the radiotherapeutic management of bilateral Wilms tumor is described. Three patients with bilateral Wilms tumor were treated at our institutions. All three patients had initial nephrectomy of the contralateral kidney followed by chemotherapy. Local excision of residual tumor in the remaining kidney was done in all three cases. A 137Cs isotopic source was placed in the tumor bed at the time of the second surgery using a simple afterloading applicator. The techniques of applicator placement, localization, and brachytherapy dosimetry are described. The minimum tumor dose varied from 16 to 25 Gy.

RESULTS

All three patients are alive and well at 28, 48, and 66 months after the procedure. There were no serious operative or postoperative sequelae.

CONCLUSIONS

This simple brachytherapy technique was effective in selected cases of bilateral Wilms tumor where a renal-sparing radiotherapy approach was needed. This technique is most applicable when there is residual intrarenal tumor after partial nephrectomy, when the tumor is unifocal, and when the tumor bed is less than 2 cm diameter.