Preoperative Wilms tumor rupture in children

Purpose

According to the guidelines of International Society of Pediatric Oncology (SIOP) and National Wilms Tumor Study (NWTS), Wilms tumor with preoperative rupture should be classified as at least stage III. Few clinical reports can be found about preoperative Wilms tumor rupture. The purpose of this study was to investigate our experience on the diagnosis, treatment and prognosis of preoperative Wilms tumor rupture.

Methods

Patients with Wilms tumor who underwent treatment according to the NWTS or SIOP protocol from January 2008 to September 2017 in Beijing Children’s Hospital were reviewed retrospectively. The clinical signs of preoperative tumor rupture were acute abdominal pain, and/or fall of hemoglobin. The radiologic signs of preoperative tumor rupture are as follows: (1) retroperitoneal and/or intraperitoneal effusion; (2) acute hemorrhage located in the sub-capsular and/or perirenal space; (3) tumor fracture communicating with peritoneal effusion; (4) bloody ascites. Patients with clinical and radiologic signs of preoperative tumor rupture were selected. Patients having radiologic signs without clinical symptoms were also selected. The clinical data, treatments and outcomes were analyzed. Meanwhile, patients without preoperative Wilms tumor rupture during the same period were collected and analyzed.

Results

565 Patients with Wilms tumor were registered in our hospital. Of these patients, 45 patients were diagnosed with preoperative ruptured Wilms tumor. All preoperative rupture were confirmed at surgery. Spontaneous tumor rupture occurred in 41 patients, the other 4 patients had traumatic history. Of the 45 patients, 41 were classified as stage III, 3 patients with pulmonary metastases were classified as stage IV, and one patient with bilateral tumors were classified as stage V. Of these patients with preoperative tumor rupture at stage III, 30 patients had clinical and radiologic signs of tumor rupture, the other 11 patients had radiologic signs without clinical symptoms. Among the 41 patients at stage III, 13 patients had immediate surgery without preoperative chemotherapy (immediate group), and 28 patients had delayed surgery after preoperative chemotherapy (delayed group). In immediate group, 12 patients had localized rupture, 1 patient underwent emergency surgery because of continuous bleeding. In delayed group, 4 had inferior vena cava tumor embolus (1 thrombus extended to inferior vena cava behind the liver, three thrombi got to the right atrium), 4 crossed the midline with large tumors, 20 had extensive rupture without localization. In immediate group, tumor recurrence and metastasis developed in 2 patients, and no death occurred. In the delayed group, tumor recurrence and metastasis developed in 8 patients, and 7 patients died. During the same period, 41 patients were classified as stage III without preoperative rupture. In the non-ruptured group, tumor recurrence and metastasis developed in 3 patients, and 4 patients died. The median survival time in the ruptured group (both immediate group and delayed group) and non-ruptured group were (85.1 ± 7.5) and (110.3 ± 5.6) months, and the 3-year cumulative survival rates were 75.1% and 89.6%, respectively. The overall survival rate between the ruptured and non-ruptured groups showed no statistic difference (P = 0.256). However, there was significant difference in recurrence or metastasis rate between the ruptured and non-ruptured groups (24.4% vs 7.3%; P = 0.031).

Conclusion

Contrast-enhanced computed tomography (CT) and ultrasonography (US) are of major value in the diagnosis of preoperative tumor rupture, and immediate surgery or delayed surgery are available therapeutic methods. The treatment plan was based on patients’ general conditions, tumor size, position and impairment degree of tumor rupture, extent of invasion and experience of a multidisciplinary team (including surgeon and anesthesiologists). In our experience, for ruptured preoperative tumor diagnosed with stage III, the criteria for immediate surgery are as follows: tumor not acrossing the midline, tumor without inferior vena cava thrombus, localized rupture, being capable of complete resection. Selection criteria for delayed surgery after preoperative chemotherapy are as follows: large tumors, long inferior vena cava tumor thrombus, tumors infiltrating to surrounding organs, unlocalized rupture, tumors can not being resected completely. Additionally, patients with preoperative Wilms tumor rupture had an increased risk of postoperative recurrence or metastasis.

     

Management of unresectable Wilms tumor

Wilms tumor has become a model of highly curable cancer. With the addition and refinement of chemotherapy protocols, survival rates have risen from 20 per cent three decades ago to 80 per cent or greater in the past decade. Surgery remains an integral part of the management of Wilms tumor both as a diagnostic tool and for removal of tumor bulk. Few primary tumors cannot be surgically removed during the initial phase of therapy. However, bilateral Wilms tumor and large unilateral tumors may occasionally be initially unresectable without prohibitive loss of renal or nonrenal organ function. The National Wilms Tumor Study group has no protocol for management of these tumors but does offer guidelines unsupported by large numbers of patients. Two cases are presented in which the tumors were initially deemed surgically unresectable. Initial management with chemotherapy (both cases) and radiotherapy (1 case) followed by surgical removal of tumor left both patients free of gross tumor, with relapse-free survivals of two and one-half years and six years thus far. Based on our experience and that found in the literature, we believe that preoperative chemotherapy is indicated for children suspected of having Wilms tumors judged surgically unresectable.     

Wilms tumor in horseshoe kidneys: a report from the National Wilms Tumor Study

An analysis of information on 2,961 patients with Wilms tumor entered in the National Wilms Tumor Study up to July 1983 revealed 13 tumors occurring in horseshoe kidneys. The correct preoperative diagnosis was made in 6 of the 13 patients. At presentation 5 patients had stage 1, 3 stage 2 and 5 stage 3 disease. Major preoperative or intraoperative tumor spillage occurred in 3 patients. The over-all survival rate was 85 per cent after a mean followup of 45 months. The surgical, pathological and therapeutic aspects of Wilms tumor in horseshoe kidneys were analyzed carefully. The frequency of horseshoe kidneys in patients with Wilms tumor registered with the National Wilms Tumor Study was determined and was used in conjunction with population data to estimate the relative risk of Wilms tumor occurrence in children with horseshoe kidneys.     

p53 immunopositivity in histologically favorable Wilms tumor is not related to stage at presentation or to biological aggression

PURPOSE: Previous studies have suggested that increased p53 expression is associated with advanced stage and biologically aggressive (chemotherapy resistant) Wilms tumors. We decided to test the hypothesis that increased immunopositivity of p53 is associated with biological aggressiveness in patients with histologically favorable Wilms tumors. MATERIALS AND METHODS: We reviewed the charts of all patients with unilateral Wilms tumor treated at our institution between 1976 and 2001. Histological characteristics, tumor stage, clinical course and p53 expression as determined by immunohistochemical analysis were determined. All immunohistological evaluations were performed on tissue obtained before administration of chemotherapy. RESULTS: A total of 63 cases of unilateral histologically favorable Wilms tumor were assessed. Five cases (8%) were p53 positive. No significant relationship to p53 expression or stage at presentation was noted in 1 of 21 (5%) stage 1, 3 of 21 (14%) stage 2, 1 of 11 (9%) stage 3 and 0 of 10 stage 4 tumors positive for up-regulation of p53. Of the 5 patients with up-regulated p53 expression 1 (20%) had documented disease progression or relapse while on standard National Wilms Tumor Study chemotherapy. Of the 58 patients who were p53 negative 10 (17%) had disease progression or relapse while on standard National Wilms Tumor Study chemotherapy (p >0.3). CONCLUSION: In contrast to previously published studies, we found no correlation of p53 expression to either tumor stage at presentation (p >0.3) or prognosis (p >0.3) in individuals with histologically favorable Wilms tumor assessed for immunopositivity before administration of chemotherapy.     

Metachronous bilateral Wilms tumor. Report of longest-known survivor and guidelines for conservative management

In a one-year-old black male patient a classic Wilms tumor of the left kidney was treated with left nephrectomy, chemotherapy, and irradiation to the entire abdomen. Two years later a mature Wilms tumor, consisting predominantly of rhabdomyomatous elements, was discovered in the right kidney. Although a second course of chemotherapy was given and 2,000 rad were delivered to the right flank, the mass continued to enlarge with progressive deterioration of renal function. A nephron-sparing procedure was performed, in which a 3,400-g tumor measuring 19 cm X 16 cm X 9 cm was enucleated from the right kidney without compromise to the remaining normal tissue. Pathologic examination of the surgical specimen revealed a mature Wilms tumor with a malignant anaplastic sarcoma arising in the central portion. Currently, he is disease-free with normal renal function more than twenty years after diagnosis of the metachronous bilateral Wilms tumor. We believe he is the longest known surviving metachronous Wilms tumor patient and emphasizes the importance of conservative, meticulous surgery in the management of both unilateral and bilateral Wilms tumors. The role of multimodal therapy (chemotherapy, irradiation, and surgery) as well as the current guidelines for the management of bilateral Wilms tumors as proposed by the National Wilms Tumor Study are reviewed.     

The occurrence of Wilms tumor in horseshoe kidneys: a report from the National Wilms Tumor Study Group (NWTSG)

Background/Purpose: An increased incidence of Wilms tumor has been noted in patients with a horseshoe kidney. These represent a difficult diagnostic and therapeutic challenge. The charts of all National Wilms Tumor Study Group (NWTSG) patients with Wilms tumor occurring in a horseshoe kidney were reviewed. Methods: From 1969 to 1998, 8,617 patients were enrolled in the NWTSG. Forty-one patients were found to have a Wilms tumor arising in a horseshoe kidney for an incidence of 0.48%. Their records were reviewed retrospectively. Results: Horseshoe kidney was not recognized preoperatively in 13 patients, 10 of whom were evaluated with computed tomography (CT). Four of the 10 also had renal ultrasonography and one an intravenous pyelogram (IVP). Two of the 13 were evaluated with an IVP only, and the last had no preoperative imaging studies performed. Stage at presentation was stage I, 10 pts; stage II, 10; stage III, 12; stage IV, 6; stage V, 3. Primary surgical resection was performed in 26 patients, including 23 nephrectomies and 3 partial nephrectomies. Fifteen children were treated with preoperative chemotherapy after initial biopsy of the tumor. The mean total remaining renal parenchyma after all operations (excluding treatment of relapses) was approximately 75%. Surgical complications occurred in 14.6% of patients, including 2 urine leaks, 2 ureteral obstructions, and 1 ureteral injury. Two patients had transient renal failure. Conclusions: The diagnosis of horseshoe kidney often was missed on preoperative imaging. Accurate preoperative diagnosis is important in planning the operative approach and may help to decrease complications related to transection of the urinary collecting system. Although 37% of patients with Wilms tumor arising in a horseshoe kidney were judged inoperable at initial exploration, all were amenable to resection after chemotherapy. J Pediatr Surg 37:1134-1137.     

Distinct features of teratoid Wilms tumor

Teratoid Wilms tumor is an unusual variant of nephroblastoma in which heterologous tissue predominates. Typically, histopathologic examination shows a mixture of mature squamous and mucus-producing columnar epithelium and a prominent component of mature adipose tissue. The treatment of this tumor has not been established because of its rarity with some reports doubting the value of chemotherapy. We report 3 new cases and review the 23 previously reported cases that we were able to identify. The first case was a 2-year-old boy with a huge tumor that occupied most of the abdominal cavity. The second case was a 5-year-old girl with a metastatic tumor in association with horseshoe kidney and is the first case of teratoid Wilms tumor with brain metastasis. The third case was an 11-month-old girl with bilateral involvement. Imaging studies of our patients were similar to those reported in the literature with areas of fat attenuation and calcification. Failure to respond to preoperative chemotherapy was seen in our patients and in most previously reported cases that were treated with preoperative chemotherapy. We recommend treating this entity with protocols designed for Wilms tumor and to conduct further basic research to understand its biologic nature.     

Intravascular Extension of Wilms Tumor

OBJECTIVE: To define the incidence and manifestations of and optimal therapy for children with intravascular extension of Wilms tumor. METHODS: Children on a collaborative study of Wilms tumor who had intravascular extension into the inferior vena cava (IVC) or atrium were identified. Surgical checklists and surgical and pathology reports were reviewed. RESULTS: One hundred sixty-five of 2,731 patients had intravascular extension of Wilms tumor. The level of extension was IVC in 134 and atrium in 31. Sixty-nine had received preoperative therapy (55 with IVC extension and 14 with atrial extension) for a median of 8 weeks. Complications during preoperative chemotherapy were seen in five patients (tumor embolism and tumor progression in one each, and three with adult respiratory distress syndrome, one of which was fatal). The intravascular extension of the tumor regressed in 39 of 49 children with comparable pre- and posttherapy radiographic studies, including 7 of 12 in whom the tumor regressed from an atrial location, thus obviating the need for cardiopulmonary bypass. Surgical complications occurred in 36.7% of the children in the atrial group and 17.2% in the IVC group. The frequency of surgical complications was 26% in the primary resection group versus 13.2% in children with preoperative therapy. When all the complications of therapy were considered, including those that occurred during the interval of preoperative chemotherapy (one of the five also had a surgical complication), the incidence of complications among those receiving preoperative therapy was not statistically different from the incidence among those who underwent primary resection. The difference in 3-year relapse-free survival (76.9% for 165 patients with intravascular extension, 80.3% for 1,622 patients with no extension) was not statistically significant whether or not it was adjusted for stage and histology. CONCLUSIONS: Preoperative treatment of these children may facilitate resection by decreasing the extent of the tumor thrombus, but the overall frequency of complications is similar in both groups.     

Evaluation of effect of preoperative chemotherapy on Wilms' tumor histopathology

Purpose

To evaluate usefulness of cutting needle biopsy (CNB) to recognize pediatric renal tumors and to predict the evolution of histology during preoperative chemotherapy of Wilms tumors.

Management and outcome of inoperable Wilms tumor. A report of National Wilms Tumor Study-3.

METHODS: The authors reviewed 131 children enrolled in National Wilms Tumor Study-3 (NWTS-3) who received preoperative treatment for tumors unable to be resected at surgery or judged inoperable by imaging evaluation. Preoperative biopsies were performed on 103 patients. Patients were assigned a pretreatment stage: stage II (11 patients), stage III (39 patients), stage IV (66 patients), and unknown (15 patients). The chemotherapy regimen included dactinomycin and vincristine (81 patients), dactinomycin, vincristine, and doxorubicin (30 patients), dactinomycin, vincristine, doxorubicin, and cyclophosphamide (10 patients), and other (8 patients). Preoperative radiation therapy was started concurrently with chemotherapy (27 patients) or because of lack of response (14 patients). Two patients were given preoperative irradiation without chemotherapy. RESULTS: Response to therapy was assessed after the first trial of chemotherapy. Partial responses were noted in 110 patients (85%), 3 had complete responses, 13 had no response or progression of disease, and 5 patients were not able to be evaluated. There were no significant differences in preoperative response to the different chemotherapy regimens. Median time interval from diagnosis to nephrectomy was 58.5 days. When compared with NWTS-3 patients not receiving preoperative treatment, survival was reduced for patients treated preoperatively (88% vs. 74%, respectively, 4-year survival), which was only partially explained by differences in stage distribution. Median duration of follow-up was 5.9 years. Lack of response to the preoperative treatment was associated with a poor prognosis. Eight children died before removal of the primary tumor. All eight had either progressive disease or no response to the preoperative treatment. CONCLUSIONS: The use of preoperative treatment can facilitate subsequent surgical resection in selected patients with inoperable Wilms tumors. Although these very large tumors--judged unable to be resected--have a somewhat worse prognosis, nephrectomy was completed in 93% of patients after preoperative treatment. However, preoperative treatment will lead to less accurate surgical and pathologic staging, and undertreatment should be avoided in these high-risk patients.     

Malignant kidney tumors in children]

The authors have examined 92 children with renal tumors. The treatment for Wilms tumor should be combined: preoperative irradiation, nephrectomy, postoperative irradiation. Late results were studied in 48 patients. 16 patients (33.3%) are living without the recurrence and metastases for over two years, including 4 over 5 years.     

Wilms' tumor management

PURPOSE OF REVIEW: The management of Wilms' tumor continues to evolve with two different approaches being taken by the National Wilms Tumor Study in North America and the International Society of Pediatric Oncology in Europe in regards to preoperative chemotherapy. Limiting the duration, dosage, and number of chemotherapeutic agents and the dosage of radiotherapy are common goals in both trials. RECENT FINDINGS: Contralateral exploration of unilateral tumors will no longer be recommended in future National Wilms Tumor Studies. Percutaneous biopsy for tissue diagnosis is quite accurate, but there are concerning complications with its use. Partial nephrectomy is successful for low risk unilateral Wilms tumor, but its indications remain controversial. The surgical complication rate was similar between the National Wilms Tumor Study and the International Society of Pediatric Oncology, but intraoperative tumor spill was higher in the North American trials. Doxorubicin decreased the risk of recurrence in stage III tumors by 50%, and its current dose is not associated with late congestive heart failure. For selected patients, shorter courses of vincristine/dactinomycin or vincristine alone show equivalent results compared to current regimens. A longer course of chemotherapy (including doxorubicin) for clear cell sarcoma improves recurrence-free survival. Patients with Wilms' tumor, aniridia, major genitourinary malformations, and mental retardation, the WAGR syndrome, have a 50% chance of unexplained end-stage renal disease 20 years after treatment. SUMMARY: Less aggressive means of diagnosis and treatment for Wilms' tumor are continuing to achieve very good cure rates while lowering long term morbidity for low risk patients. High-risk patients with unfavorable histology or the WAGR syndrome benefit from more intensive treatment and long-term follow-up.     

Management of intravascular thrombus in cases of bilateral Wilms tumor or horseshoe kidney

PurposeTo describe the oncologic and surgical management of bilateral Wilms tumor or Wilms tumor arising in a horseshoe kidney with intravenous tumor thrombus to help pediatric surgeons negotiate this rare and difficult anatomic circumstance.MethodsA single-institution, retrospective medical record review identified 4 cases of bilateral WT and one case of WT arising in a horseshoe kidney with intravenous tumor thrombus between 2009 and 2021. The presentation, imaging, chemotherapy regimen, intraoperative approach, and surgical and oncologic outcomes were reviewed for each of these patients.ResultsAll patients received a total of 12 weeks of neoadjuvant chemotherapy. In two patients, a staged approach to the bilateral tumors was undertaken with the first side being operated on after six weeks of therapy and the other side undergoing surgery after an additional six weeks of therapy. Of five patients, four underwent nephron-sparing surgery of all tumors and one underwent unilateral radical nephroureterectomy with contralateral nephron-sparing surgery. Tumor thrombectomy was performed in four of five cases; one patient demonstrated a complete response of the intravenous tumor thrombus to neoadjuvant chemotherapy and did not require thrombectomy. Three patients received adjuvant flank radiotherapy. Three patients developed medically managed stage II or III chronic kidney disease and no patient required renal replacement therapy or kidney transplant to date.ConclusionNephron-sparing surgery is feasible and safe to perform in selected cases of bilateral Wilms tumor with intravascular thrombus by utilizing three-drug neoadjuvant chemotherapy, staged approaches to each kidney when appropriate, and detailed preoperative and/or intraoperative mapping of renal venous anatomy. Successful nephron-sparing surgery with tumor thrombectomy is dependent on a branched renal venous system or the presence of accessory renal veins.Level of evidenceLevel 4.     

Wilms tumor, misdiagnosed preoperatively: a review of 19 National Wilms Tumor Study I cases.

This study establishes the difficulty in making specific diagnoses in children with retroperitoneal tumors when only excretory urograms are used in diagnosis. Complementary use of excretory urography and ultrasonography should make the number of preoperative errors less by separating cases of Wilms tumor from those with cystic disease. This investigation underscores the hazards inherent in the use of preoperative irradiation and chemotherapy, since some children with benign disease are likely to receive inappropriate therapy.     

All angiogenesis is not the same: Distinct patterns of response to antiangiogenic therapy in experimental neuroblastoma and Wilms tumor

BACKGROUND/PURPOSE: Neuroblastoma and Wilms tumor exhibit different patterns of metastasis, invasion, and therapeutic response. Vascular endothelial growth factor (VEGF) is an angiogenic factor expressed in both tumors. The authors hypothesized that because the clinical behavior of these tumors differs, the response to anti-VEGF therapy would be distinct, and tumor vascular architectures would reflect this distinction. METHODS: Xenografts were induced by intrarenal injection of cultured cells in athymic mice. After 1 week, anti-VEGF antibody or vehicle were administered for 5 weeks before sacrifice. Additional animals were maintained for 3 weeks after termination of antibody injections to assess rebound growth of tumors. Fluorescein angiography was performed in selected animals. RESULTS: Neuroblastoma control and treated tumor weights were not significantly different (1.48 g v 0.77 g, P =.34). By comparison, as previously reported, antibody-treated Wilms tumors were growth inhibited. Angiograms of treated (but not control) neuroblastomas displayed novel rounded structures at vessel branches, which the authors term terminal vascular bodies (TVBs). Wilms tumor vessels displayed no such alteration. CONCLUSIONS: Neuroblastoma xenografts are less effectively suppressed by anti-VEGF antibody than Wilms tumors. Neuroblastoma vascular architecture displays a novel alteration during antibody administration, which attenuates when antibody is withdrawn. These studies suggest that angiogenesis is differently regulated in experimental neuroblastoma and Wilms tumor.     

成人肾母细胞瘤的诊断与治疗（附12例报告）

目的探讨成人肾母细胞瘤的诊断和治疗方法。方法回顾性分析12例成人肾母细胞瘤患者的临床资料。结果本组患者年龄16-63岁,表现为肉眼血尿2例,腰腹痛6例,4例为体检发现;术前诊断为肾肿瘤9例,肾盂肿瘤3例。12例均行手术治疗,术后病理均诊断为肾母细胞瘤。按照美国国家肾母细胞瘤研究组（NWTS）分期标准,本组分别为Ⅰ期5例、Ⅱ期3例、Ⅲ期3例、Ⅳ期1例。术后辅以放疗和化疗,平均随访41个月,3年生存率为48%。结论成人肾母细胞瘤是一种比较少见的恶性肿瘤,术前确诊困难,手术治疗并辅以放疗、化疗是其主要的治疗方法。     

Peritoneal metastases after laparoscopic nephron-sparing surgery for localized Wilms tumor

A 2-year-old girl was referred for the management of the progression of her localized Wilms tumor. She had undergone laparoscopic nephron-sparing surgery for her right Wilms tumor 3 months earlier. Postoperative chemotherapy was commenced 6 weeks later. Subsequent computer tomographic evaluation 12 weeks postsurgery showed local recurrence and peritoneal tumors. These findings were confirmed at laparotomy. We report the first case of peritoneal tumor dissemination after laparoscopic nephron-sparing surgery for localized Wilms tumor.     

Wilms tumor presenting with abdominal pain: A special subgroup of patients

Background: Although significant progress has been made in the management of children with Wilms tumor, two major controversies still exist: the extent of radiographic evaluation necessary before surgery and the role of preoperative chemotherapy. This study sought to determine whether patients with Wilms tumor who presented with abdominal pain defined a special subset of patients who might require a more extensive preoperative work-up and neoadjuvant chemotherapy. Methods: From 1970 to 1995, 250 children were treated for Wilms tumor at a single pediatric institution. A retrospective chart review determined presenting signs and symptoms for each patient. Results: Thirty-four (14%) patients (mean age 5.5 years) sought medical attention with a chief complaint of abdominal pain. The stage distribution for these patients tended to be higher and was significantly different (P<.001, x²-analysis) from those presenting without pain. Four (14%) of 29 patients with tumor available for analysis were found to have anaplastic histology. Conclusion: These data suggest that patients with Wilms tumor who present with abdominal pain represent a special subgroup that tends to be older and has an increased incidence of tumor rupture, anaplasia, and higher stage. These patients may benefit from a more extensive preoperative evaluation and consideration of neoadjuvant chemotherapy.Presented at the 50th Annual Cancer Symposium of The Society of Surgical Oncology, Chicago, Illinois, March 20–23, 1997.     

Cavectomy for the treatment of Wilms tumor with vascular extension

PURPOSE: Vascular extension to the vena cava occurs in 4% of Wilms tumor cases and can reach the right atrium in up to 1%. When this happens the thrombus is usually not adherent to the vessel wall, and there is blood flow around it. Preoperative chemotherapy can cause thrombus regression and even resolution. If the thrombus persists after chemotherapy, surgery will be a challenge. On the other hand, if the thrombus invades the vessel wall, its removal may not be feasible. In this situation cavectomy is a good surgical strategy because it provides complete resection. The prerequisite for cavectomy is the absence of blood flow in the vena cava on preoperative Doppler ultrasonography. We report 3 cases of Wilms tumor with vena caval invasion in which cavectomy was performed, and discuss the principles, indications and operative technique. MATERIALS AND METHODS: A total of 171 patients with Wilms tumor were treated at our institution between 1984 and 2004. Of these patients 6 with intravascular extension of thrombus within the right atrium were treated with extracorporeal circulation, cardiac arrest and profound hypothermia, and 3 were treated with cavectomy. RESULTS: There were no instances of surgical complications or postoperative renal failure in our patients who underwent cavectomy. All remain well and free of disease. CONCLUSIONS: Cavectomy is a safe procedure for treating pediatric patients with Wilms tumor when there is extension and invasion of the vena cava wall without blood flow.     

The current management of bilateral Wilms tumor

The good prognosis of synchronous bilateral Wilms tumor seems inappropriate for the magnitude of the disease process. Our experience with 11 cases demonstrates the unusual tumor response to chemotherapy and limited preservative surgery. Although 2 patients died 2 with metastatic disease have responded to chemotherapy and are alive at 5 and 8 years after treatment. In addition, 1 patient has survived with biopsy only and no definitive surgery. Although all surgical options have been used, ranging from biopsy alone to bench surgery with autotransplantation to bilateral nephrectomy, our experience demonstrates the effectiveness of a conservative approach with initial biopsy, chemotherapy and subsequent partial nephrectomy if needed. Our survival data and the histological examination of the tumors after chemotherapy suggest a strong relationship of bilateral Wilms tumor to the nodular renal blastema-nephroblastomatosis complex, and a mechanism to explain the excellent tumor response to chemotherapy.