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Keywords:

  • Denys–Drash syndrome;
  • Frasier syndrome;
  • genetic predisposition to disease;
  • Wilms tumor;
  • WT1 proteins

Abstract

  1. Top of page
  2. Abstract
  3. INTRODUCTION
  4. PATIENTS AND METHODS
  5. RESULTS
  6. DISCUSSION
  7. Acknowledgements
  8. REFERENCES
  9. Supporting Information

Background

Children with WT1 gene-related disorders such as Denys–Drash syndrome (DDS) and Frasier syndrome (FS) are at increased risk of Wilms tumor and end-stage renal disease. We investigated whether Wilms tumors in these patients displayed a specific phenotype or behavior and whether nephron-sparing surgery was beneficial.

Procedure

We retrospectively studied all patients with DDS, FS, or other WT1 mutations treated at our institutions between 1980 and 2007.

Results

We identified 20 patients, of whom 18 had benign or malignant tumors. Wilms tumors occurred in 15 patients, being unilateral in 10 and bilateral in 5 (20 tumors). Median age at Wilms tumor diagnosis was 9 months. No patients had metastases. According to the International Society of Pediatric Oncology Working Classification, there were 19 intermediate-risk tumors and one high-risk tumor; no tumor was anaplastic. In patients with nephropathy who underwent unilateral nephrectomy for Wilms tumor or nephron-sparing surgery for bilateral Wilms tumor, mean time to dialysis was 11 or 9 months, respectively. Other tumors included three gonadoblastomas (in two patients), one retroperitoneal soft-tissue tumor, and one transitional cell papilloma of the bladder. Two patients, both with stage I Wilms tumor, died from end-stage renal disease-related complications. The median follow-up time for the 18 survivors was 136 months (range, 17–224 months).

Conclusion

Most Wilms tumors in children with WT1-related disorders were early-stage and intermediate-risk tumors, with a young age at diagnosis. In patients without end-stage renal disease, nephron-sparing surgery should be considered for delaying the onset of renal failure. Pediatr Blood Cancer 2009;52:55–59. © 2008 Wiley-Liss, Inc.


INTRODUCTION

  1. Top of page
  2. Abstract
  3. INTRODUCTION
  4. PATIENTS AND METHODS
  5. RESULTS
  6. DISCUSSION
  7. Acknowledgements
  8. REFERENCES
  9. Supporting Information

WT1 is a zinc-finger transcription-factor gene on chromosome band 11p13 that acts as a tumor suppressor and plays multiple roles during kidney and gonad development 1. Heterozygous constitutional WT1 mutations have been found in a variety of disorders associated with cancer, including Denys–Drash syndrome (DDS) 1–3 and Frasier syndrome (FS) 4, 5. DDS consists of 46,XY disorder of sex development, Wilms tumor, and congenital nephropathy leading to end-stage renal disease 6, 7; whereas FS is characterized by 46,XY complete gonadal dysgenesis and nephrotic syndrome, occasionally with Wilms tumor or gonadoblastoma 4, 8, 9. Both are rare and complex syndromes that pose difficult treatment problems. The occurrence of Wilms tumor in a patient at risk for, or having, severe renal failure creates specific challenges. Whether nephron-sparing surgery or definitive bilateral nephrectomy is best remains unclear.

We investigated whether Wilms tumors in children with WT1-related disorders exhibited specific characteristics regarding phenotype, behavior, and prognosis. A secondary goal was to assess the impact of nephron-sparing surgery on the outcome of these patients. Based on our results, we suggest recommendations for the management of Wilms tumor in children with WT1 mutations.

PATIENTS AND METHODS

  1. Top of page
  2. Abstract
  3. INTRODUCTION
  4. PATIENTS AND METHODS
  5. RESULTS
  6. DISCUSSION
  7. Acknowledgements
  8. REFERENCES
  9. Supporting Information

We retrospectively studied patients with DDS, FS, or other WT1 mutations managed at either of two pediatric teaching hospitals (Necker or Trousseau) between 1980 and 2007. We included all patients who met at least two of the following four criteria: Wilms tumor, 46,XY disorder of sex development, glomerular disease with proteinuria, and constitutional WT1 point mutations.

The following data were extracted from each patient chart: assigned gender, clinical phenotype, tumor type and stage, age at diagnosis of the tumor(s), surgical management, adjuvant therapies, histopathological results, and long-term follow-up findings. If available, karyotype and WT1 mutations were correlated to our findings. WT1 from leukocyte genomic DNA was sequenced as described elsewhere 1, 10. Written informed consent was obtained from the parents before each surgical procedure, each genetic analysis and karyotyping. The following classifications were used: Revised International Society of Pediatric Oncology (SIOP) Working Classification, SIOP Staging Criteria of Renal Tumors of Childhood 11, and Consensus Statement on Management of Intersex Disorders 12.

RESULTS

  1. Top of page
  2. Abstract
  3. INTRODUCTION
  4. PATIENTS AND METHODS
  5. RESULTS
  6. DISCUSSION
  7. Acknowledgements
  8. REFERENCES
  9. Supporting Information

We identified 20 patients with DDS, FS, or other WT1 mutations who met our inclusion criteria (Table I). Median follow-up time for the 20 patients was 113 months (range, 8–224 months). Twenty Wilms tumors occurred in 15 of these patients. Mean and median ages at Wilms tumor diagnosis were 13.5 and 9 months, respectively (range, 1–40 months). The tumor was unilateral in 10 patients and bilateral in 5. Thirteen tumors were stage I, four were stage II, and three were stage III.

Table I. Characteristics of the 20 Patients With WT1-Related Disorders
Pt #KarAssign. genderExternal genitaliaProtNephrotic syndromeRenal failureWilms tumor (age in months)Kidney surgeryWT1 mutationFollow-up in months
  • Pt, patient; Kar, karyotype; Assign. gender, assigned gender; Prot, proteinuria; ESRD, end-stage renal disease; IR, intermediate risk; HR, high risk, ILNR, intralobar nephrogenic rests; DMS, diffuse mesangial sclerosis.

  • a

    Because of ESRD;

  • b

    Other tumor;

  • c

    Contralateral partial nephrectomy for suspected Wilms tumor subsequently found to be ILNR by histological examination.

 1XYFemaleFemale phenotypeYesYes (focal and segmental glomerular sclerosis)ESRDNobRight nephrectomya + renal transplantIntron 9210
 2XYMaleHypospadias, bilateral cryptorchidismYesYes (nonspecific)ESRDNoBilateral nephrectomya − renal transplantExon 9209
 3XYMaleHypospadias, bilateral cryptorchidismYesYes (DMS)ESRDUnilateral IR stage I (8)Unilateral extended nephrectomy − Contralateral nephrectomyaND33 (died)
 4XYFemaleHypospadias, bilateral cryptorchidismYesYes (DMS)ESRDUnilateral IR stage I (7)NoND8 (died)
 5XYFemaleHypospadias, bilateral cryptorchidismYesYes (DMS)ESRDNoBilateral nephrectomya − renal transplantExon 9180
 6XYMaleHypospadias, bilateral cryptorchidismNoNoNoBilateral synchronous IR stage I (18) + ILNRUnilateral extended nephrectomy + contralateral tumorectomyExon 7219
 7XYFemaleHypospadias, bilateral cryptorchidismYesYes (atypical DMS)ESRDNobBilateral nephrectomya − renal transplantExon 9156
 8XYMaleHypospadias, bilateral cryptorchidismNoNoNoUnilateral IR stage I (6)Unilateral extended nephrectomy + Redux surgery for local relapseExon 4224
 9XYFemaleFemale phenotype.YesYes (DMS)ESRDNobBilateral nephrectomya − renal transplantIntron 9116
10Not doneMaleBilateral cryptorchidismYesNoMildBilateral synchronous IR stages I and III (9)Bilateral partial nephrectomyExon 9186
11Not doneMaleUnilateral cryptorchidismYesYes (DMS)ESRDBilateral synchronous IR stages I and II (18)Unilateral extended nephrectomy + contralateral partial nephrectomy − renal transplant + nephrectomyaExon 9109
12XYMaleBilateral cryptorchidismNoNoNoUnilateral IR stage I (15) + ILNRcUnilateral extended nephrectomy + contralateral partial nephrectomycExon 736
13XYMaleHypospadias, bilateral cryptorchidismYesYesNoUnilateral HR stage III (3)Unilateral extended nephrectomyIntron 931
14XYMaleHypospadias, bilateral cryptorchidismYesYesESRDBilateral metachronous stage I IR (1 and 4)Bilateral partial nephrectomy − bilateral nephrectomyaExon 929
15XXFemaleFemale phenotypeYesYes (DMS)ESRDBilateral synchronous IR stage I (8) + ILNRUnilateral extended nephrectomy + contralateral partial nephrectomy renal transplant + nephrectomyaExon 9222
16XXFemaleFemale phenotypeYesYes (DMS)ESRDUnilateral IR stage II (27)Unilateral extended nephrectomy − Contralateral nephrectomya − renal transplantExon 9107
17XXFemaleFemale phenotypeYesYes (mesangial hyperplasia)ESRDUnilateral IR stage III (40)bUnilateral extended nephrectomy − Contralateral nephrectomya + renal transplantExon 9110
18XXFemaleFemale phenotypeYesNoNoUnilateral IR stage II (14)Unilateral extended nephrectomyExon 364
19XXFemaleFemale phenotype.YesYes (DMS)ESRDUnilateral IR stage I (9)Unilateral extended nephrectomy − Contralateral nephrectomya − renal transplantExon 9198
20XXFemaleFemale phenotypeYesYes (DMS)ESRDUnilateral IR stage II (19) + ILNRUnilateral extended nephrectomy − Contralateral nephrectomyaExon 917

Phenotype and Genotype

In the patients with a normal female phenotype and Wilms tumor, WT1-related disease was suspected before surgery because of proteinuria at diagnosis or during treatment. In male patients with ambiguous phenotype or cryptorchidism, WT1-related disease was suspected when Wilms tumor and/or proteinuria occurred.

The molecular diagnosis was available for 13 of the 15 patients with Wilms tumor and showed constitutional heterozygous point mutations in the WT1 gene. All 11 patients with point mutations in exon 9 progressed to renal failure. One XX patient with a mutation in exon 3 had isolated proteinuria throughout the 6-year follow-up. No proteinuria or nephropathy occurred in the three patients with 46,XY disorder of sex developments and mutations in exon 4 or 7. Two patients died before the molecular diagnosis of WT1 mutations became available.

Initial Treatment and Surgery

Eleven patients received primary chemotherapy consisting of vincristine with actinomycin D according to SIOP clinical trial regimen for 4 weeks (10 patients) or 8 weeks (1 patient). The usual doses used were 1.5 mg/m2/dose for vincristine and 45 mcg/kg/dose for actinomycin D. One patient received primary chemotherapy with ifosfamide, vincristine, and actinomycin D because the initial biopsy suggested an undifferentiated sarcoma. Three patients had primary surgery. Fourteen patients underwent surgery for Wilms tumor, and one patient died before surgery. Of the nine patients with unilateral Wilms tumors, seven underwent extended total unilateral nephrectomy because they did not have end-stage renal disease. Bilateral nephrectomy was performed in one patient with unilateral Wilms tumors and end-stage renal disease. One patient with suspected bilateral Wilms tumor underwent bilateral partial nephrectomy and histological studies showed unilateral stage I Wilms tumor with two nephrogenic rests on the other side. Of the four patients with synchronous bilateral Wilms tumor, three underwent extended unilateral nephrectomy with contralateral tumorectomy or partial nephrectomy, and one had bilateral partial nephrectomy. One patient had left partial nephrectomy at 2 months of age for Wilms tumor and was found by ultrasound screening 3 months later to have a metachronous Wilms tumor on the right side, which was managed by right partial nephrectomy. End-stage renal disease occurred 9 months later, and bilateral nephrectomy was therefore performed.

Among the five patients with nephropathy but no end-stage renal disease at diagnosis who underwent unilateral nephrectomy for Wilms tumor, the mean time from surgery to dialysis was 11 months (range, 2–16 months), and at last follow-up two patients did not have end-stage renal disease, 25 months and 4 years after surgery, respectively. Among the four patients with nephropathy and bilateral Wilms tumor who underwent nephron-sparing surgery, mean time from surgery to dialysis was 9 months (range, 3–17 months), and at last follow-up 15 years after surgery one patient did not have end-stage renal disease.

Histology

Of the 20 Wilms tumors, 12 exhibited a mixed histology. Presence of a stromal component and muscular differentiation were common (16 and 13 tumors, respectively). There were no anaplastic tumors. According to the SIOP Classification 11, one tumor was high-risk (blastemal type in a previously treated patient) and 19 were intermediate-risk.

Intralobar nephrogenic rests (ILNR) were seen in the renal parenchyma surrounding the tumor in five kidneys (four patients), with features of nephroblastomatosis in two patients. Perilobar nephrogenic rests were not observed. ILNR, stromal predominance, or muscular differentiation was not associated with a specific mutation type.

The renal parenchyma surrounding the tumor was suitable for histological examination in 11 kidneys and showed typical diffuse mesangial sclerosis, mesangial hyperplasia, or mesangial thickening. These findings contributed to the diagnosis of WT1-related disease.

Post-Operative Chemotherapy

Among the five patients with unilateral stage I Wilms tumor, two underwent a brief course of post-operative chemotherapy with vincristine and actinomycin D, whereas three received no chemotherapy. Ultrasound screening was positive in two of these three patients, 3 and 4 months after surgery, respectively, and showed a metachronous contralateral Wilms tumor in one patient and an ipsilateral local relapse in the other. Both patients achieved a complete remission after treatment, which consisted of chemotherapy, surgery and radiotherapy in the patient with local relapse and surgery alone in the patient with a contralateral tumor. All the three patients with unilateral stage II Wilms tumor received postoperative chemotherapy. Both patients with unilateral stage III Wilms tumor were treated with postoperative chemotherapy and radiotherapy. Of the four patients with bilateral synchronous Wilms tumor, three received postoperative chemotherapy with vincristine and anthracycline and one received no chemotherapy. Radiotherapy was not used in a patient with bilateral stage I and III Wilms tumor, in order to preserve the function of the remaining kidney parenchyma. Serious adverse events related to chemotherapy included arterial hypertension in four patients, veno-occlusive disease in two, severe thrombocytopenia with bleeding in one, transient 3rd and 6th cranial nerve palsy in one, severe varicella in one, and anthracycline-induced cardiomyopathy in one. Doses were reduced to two-thirds of the usual doses in patients with hematological toxicity or who weighed less than 12 kg.

Follow-Up and Deaths

Of the 15 patients with Wilms tumor, 13 were alive and in complete remission with a median follow-up time after surgery of 104 months (range, 15–212 months). One patient died at 8 months of age from end-stage renal disease-related multiple organ failure during neo-adjuvant chemotherapy. Another patient died at 33 months of age from overwhelming peritonitis during peritoneal dialysis.

Seven patients underwent removal of the contralateral or remaining kidney when end-stage renal disease developed, 3 to 48 months (mean, 17 months) after initial surgery. In the other six patients, who had residual renal parenchyma, ultrasound follow-up showed no evidence of relapse; mean follow-up after surgery in this subgroup was 6 years (range, 2–15 years).

Patients Without Renal Tumor

Five patients with WT1 mutations had no evidence of renal neoplasm at any time during follow-up (median, 180 months; range, 116–210). Among them, four underwent bilateral nephrectomy for end-stage renal disease at a median age of 48 months (range, 13–69 months).

Other Tumors

Three gonadoblastomas were found upon histological examination of bilateral gonadectomy specimens from two XY patients raised as females (patients #7 and #9). A retroperitoneal soft-tissue tumor occurred in a 22-year-old female with FS (patient #1), and a transitional cell papilloma of the bladder occurred in a 9-year-old female (patient #17). Details about these tumors are available in an online supplement on the PBC website.

DISCUSSION

  1. Top of page
  2. Abstract
  3. INTRODUCTION
  4. PATIENTS AND METHODS
  5. RESULTS
  6. DISCUSSION
  7. Acknowledgements
  8. REFERENCES
  9. Supporting Information

We report the features and long-term outcome of Wilms tumors in a large group of patients with WT1-related diseases. We identified a number of features that seem characteristic of Wilms tumors related to WT1 mutations. First, mean and median ages at diagnosis were 13.5 and 9 months, respectively, indicating a far earlier onset compared to the general population of patients with Wilms tumor 13. Second, five (33%) of the patients had bilateral tumors, compared to only 6% in the general population. Most of the tumors were early-stage lesions, with only 4 of 20 tumors being stage III and none causing metastases. Of the 15 patients, 14 had intermediate-risk Wilms tumors. Smooth or striated muscle differentiation was noted in 13 (65%) of the 20 tumors, in keeping with previous data from patients with WT1 mutations 14, 15. WT1 inactivation may be an early event leading to the formation of nephrogenic rests and/or nephroblastomatosis 16. ILNR has been found in 83% of patients with complete DDS 17, whereas only 4 (27%) of our 15 patients with Wilms tumors had ILNR.

WT1 Mutations and Wilms Tumors

Constitutional point mutations of the WT1 gene were identified in 18 of our 20 patients. WT1 encodes a transcription factor containing four zinc-finger regions. This transcription factor exists as two main isoforms that differ regarding the presence of three amino acids 4, 18.

We found no correlation between the type of WT1 mutation and the occurrence of Wilms tumor or of specific histopathological features. Conversely, there was a strong correlation between mutations in exon 9 or intron 9 and the development of nephropathy leading to end-stage renal disease. Exon 9 is part of the zinc finger-encoding region of the WT1 gene and is a hot spot for mutations in DDS patients, whereas heterozygous constitutional point mutations in intron 9 of WT1 are typical of FS 4. Constitutional and somatic WT1 mutations are infrequent in patients with sporadic Wilms tumors 19, 20. Whether all types of WT1 mutations predispose to cancer is unclear. Wilms tumor is rare in FS, with a single reported case to date 9. In our cohort, two patients with heterozygous constitutional point mutations in intron 9 of WT1 exhibited all the features of FS and did not develop Wilms tumor. The third patient with an intron 9 mutation, who was an XY child with hypospadias and cryptorchidism, was diagnosed with unilateral stage III Wilms tumor at 3 months of age and with nephrotic syndrome 20 months after surgery.

When and Why Should Patients With Wilms Tumor be Investigated for WT1 Mutations?

All patients with Wilms tumor should be examined for clinical evidence of cancer predisposition syndrome. Clinical and laboratory features of WT1-related disease include ambiguous genitalia or cryptorchidism, proteinuria, elevated serum creatinine and urea, and diffuse mesangial sclerosis. Diffuse mesangial sclerosis is typical of DDS 21. Patients with any of these signs should be tested for WT1 mutations. Uncertainty persists about whether DNA sequencing of the WT1 gene is beneficial in patients who have apparently sporadic Wilms tumor with predominant stromal features, INLR, or early age; this approach has been advocated by Little et al. 19.

Treatment

The identification of a constitutional WT1 mutation may influence the surgical and oncologic management of patients with Wilms tumors. Chemotherapy must be tailored to the weight and renal function of each patient. The presence of arterial hypertension and nephrotic syndrome, which increase the risk for thrombotic events, should be carefully taken into account by surgeons and anesthesiologists. The appropriateness of nephron-sparing surgery in patients with Wilms tumor and WT1 mutations deserves discussion. In patients with end-stage renal disease, we recommend bilateral nephrectomy even when the tumor is unilateral. We advocate nephron-sparing surgery in patients who have bilateral tumors without end-stage renal disease, to postpone the onset of renal failure requiring dialysis. Nephron-sparing surgery may also be beneficial in patients with unilateral Wilms tumors and constitutional point mutations in exons 8–9 or intron 9, who are at high risk of progression to end-stage renal disease. In our study, among patients with nephropathy who underwent unilateral nephrectomy for unilateral Wilms tumor or nephron-sparing surgery for bilateral Wilms tumor, dialysis was not needed until 11 months and 9 months after surgery, respectively (range, 2–17 months). Expertise in surgical oncology and nephron-sparing surgery is crucial to maximize the benefits from these procedures. A non-tumor-free margin is associated with worse tumor stage, a subsequent need for intensified therapy, and a higher risk of relapse. After nephron-sparing surgery, ultrasound follow-up is essential to identify a recurrence or metachronous contralateral tumor at an early stage. We successfully managed one patient with local relapse and one patient with metachronous stage I contralateral tumor, both tumors identified by regular ultrasound follow-up. Patients with DDS who progress to end-stage renal disease after undergoing nephron-sparing surgery for Wilms tumor should undergo total nephrectomy before renal transplantation to prevent recurrences under immunosuppressive therapy. We also recommend waiting at least 2 years between the end of Wilms tumor treatment and renal transplantation.

Prognosis

The prognosis of WT1-related Wilms tumor does not seem worse than that of sporadic Wilms tumor. None of our patients had metastases or anaplastic tumors, and only one had a blastemal tumor. Two patients died from complications of end-stage renal disease.

In conclusion, our results suggest recommendations for achieving the best compromise between conservative management (including nephron-sparing surgery) and oncologic safety (including cancer-screening protocols and definitive nephrectomy when appropriate). Patients with WT1-related disorders suffer from a huge burden of disease related to the combination of cancer predisposition, high risk of early renal failure, impaired genital development, and long-term risks of gonadal deficiency and infertility. Establishing genotype–phenotype correlations and collecting information on long-term outcomes of WT1-related disease should help healthcare professionals offer high-quality and individually tailored care to these patients.

Acknowledgements

  1. Top of page
  2. Abstract
  3. INTRODUCTION
  4. PATIENTS AND METHODS
  5. RESULTS
  6. DISCUSSION
  7. Acknowledgements
  8. REFERENCES
  9. Supporting Information

We are grateful to the physicians and other healthcare professionals who made this study possible by taking care of the patients over the years. We thank Dr. C Loirat for helpful comments about the manuscript.

REFERENCES

  1. Top of page
  2. Abstract
  3. INTRODUCTION
  4. PATIENTS AND METHODS
  5. RESULTS
  6. DISCUSSION
  7. Acknowledgements
  8. REFERENCES
  9. Supporting Information

Supporting Information

  1. Top of page
  2. Abstract
  3. INTRODUCTION
  4. PATIENTS AND METHODS
  5. RESULTS
  6. DISCUSSION
  7. Acknowledgements
  8. REFERENCES
  9. Supporting Information

Additional supporting information may be found in the online version of this article.

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