Malignant renal tumours incidence and survival in European children (1978-1997): report from the Automated Childhood Cancer Information System project

Unusual association of non-anaplastic Wilms tumor and Cornelia de Lange syndrome: case report

Background

Cornelia de Lange syndrome is the prototype for cohesinopathy disorders, which are characterized by defects in chromosome segregation. Kidney malformations, including nephrogenic rests, are common in Cornelia de Lange syndrome. Only one post-mortem case report has described an association between Wilms tumor and Cornelia de Lange syndrome. Here, we describe the first case of a living child with both diseases.

Case presentation

Non-anaplastic triphasic nephroblastoma was diagnosed in a patient carrying a not yet reported mutation in NIPBL (c.4920 G > A). The patient had the typical facial appearance and intellectual disability associated with Cornelia de Lange syndrome in absence of limb involvement. The child’s kidneys were examined by ultrasound at 2 years of age to exclude kidney abnormalities associated with the syndrome. She underwent pre-operative chemotherapy and nephrectomy. Seven months later she was healthy and without residual detectable disease.

Conclusion

The previous report of such co-occurrence, together with our report and previous reports of nephrogenic rests, led us to wonder if there may be any causal relationship between these two rare entities. The wingless/integrated (Wnt) pathway, which is implicated in kidney development, is constitutively activated in approximately 15–20 % of all non-anaplastic Wilms tumors. Interestingly, the Wnt pathway was recently found to be perturbed in a zebrafish model of Cornelia de Lange syndrome. Mutations in cohesin complex genes and regulators have also been identified in several types of cancers. On the other hand, there is no clear evidence of an increased risk of cancer in Cornelia de Lange syndrome, and no other similar cases have been published since the fist one reported by Cohen, and this prompts to think Wilms tumor and Cornelia de Lange syndrome occurred together in our patient by chance.

Evidence for a delay in diagnosis of Wilms' tumour in the UK compared with Germany: implications for primary care for children

The UK has a longstanding system of general practice which provides the vast majority of primary care, including that for children. It acts as a 'gatekeeper' to more specialist care. Parents may also use accident and emergency departments as their first point of medical contact for their children. Outcomes in the UK for many conditions in children appear to be worse than in comparable European countries where there is direct access to care by paediatricians. We have therefore looked at pathways to diagnosis and compared outcomes in the childhood kidney cancer, Wilms' tumour, which has been treated in the UK and Germany within the same clinical trial for over a decade. We find that Wilms' tumours are significantly larger in volume and have a more advanced tumour stage at diagnosis in the UK compared to Germany. There is a small (∼3%) difference in event free and overall survival between the two countries. Our data suggest that the system of primary care for children in the UK is less likely to result in the incidental finding of an abdominal mass in a child with no or vague symptoms. This may be a reason for the poorer outcome.

Association between residential proximity to environmental pollution sources and childhood renal tumors

BACKGROUND

Few risk factors for childhood renal tumors are well established. While a small fraction of cases might be attributable to susceptibility genes and congenital anomalies, the role of environmental factors needs to be assessed.

OBJECTIVES

To explore the possible association between residential proximity to environmental pollution sources (industrial and urban areas, and agricultural crops) and childhood renal cancer, taking into account industrial groups and toxic substances released.

METHODS

We conducted a population-based case-control study of childhood renal cancer in Spain, including 213 incident cases gathered from the Spanish Registry of Childhood Tumors (period 1996-2011), and 1278 controls individually matched by year of birth, sex, and region of residence. Distances were computed from the respective subject's residences to the 1271 industries, the 30 urban areas with ≥75,000 inhabitants, and the agricultural crops located in the study area. Using logistic regression, odds ratios (ORs) and 95% confidence intervals (95%CIs) for categories of distance to pollution sources were calculated, with adjustment for matching variables and socioeconomic confounders.

RESULTS

Excess risk (OR; 95%CI) of childhood renal tumors was observed for children living near (≤2.5km) industrial installations as a whole (1.97; 1.13-3.42) - particularly glass and mineral fibers (2.69; 1.19-6.08), galvanization (2.66; 1.14-6.22), hazardous waste (2.59; 1.25-5.37), ceramic (2.35; 1.06-5.21), surface treatment of metals (2.25; 1.24-4.08), organic chemical industry (2.22; 1.15-4.26), food and beverage sector (2.19; 1.18-4.07), urban and waste-water treatment plants (2.14; 1.07-4.30), and production and processing of metals (1.98; 1.03-3.82) -, and in the proximity of agricultural crops (3.16; 1.54-8.89 for children with percentage of crop surface ≥24.35% in a 1-km buffer around their residences).

CONCLUSIONS

Our study provides some epidemiological evidence that living near certain industrial areas and agricultural crops may be a risk factor for childhood renal cancer.

[Secondary TFE3-associated renal cell carcinoma in a child treated for Ewing sarcoma]

Renal cell carcinoma is a rare pediatric malignant tumor of the kidney. Unlike Wilms tumor, the efficacy of chemotherapy and radiation therapy in pediatric renal cell carcinoma remains uncertain. Surgery is the best treatment and prognosis is favorable when the tumor is localized and completely eradicated. We report an exceptional observation in a 7-year-old girl with renal cell carcinoma who had been treated 20 months previously for Ewing sarcoma with chemotherapy and radiotherapy. The renal tumor was revealed by abdominal pain without hematuria. She underwent a radical nephrectomy, and histopathology concluded in renal carcinoma associated with translocation Xp 11.2 grade 3 of Furhrman pT3a N1. No adjuvant therapy was given. After 3 years of follow-up, there is no evidence of local or metastatic recurrence. This observation is significant given the very young age of this patient, the occurrence after Ewing sarcoma with a short disease-free interval. It seems that translocation renal cell carcinoma is associated with previous exposure to chemotherapy, particularly topoisomerase II inhibitors or alkylating agents.

Clinicohistological characteristics of renal cell carcinoma in children: A multicentre study

INTRODUCTION

In this retrospective multicentre study, we compared the clinicohistological characteristics of renal cell carcinoma (RCC) between pediatric and adult patients.

METHODS

Data for patients who underwent radical or partial nephrectomy for RCC between 1988 and 2014 at multiple institutions were collected. Patients were divided into 2 groups according to age at diagnosis: pediatric patients (age ≤18 years) and adult patients (age ≥40 years). The groups were compared for clinical and pathologic variables, and survival analysis was performed.

RESULTS

The median follow-up period was 64 (range: 30-91) months for pediatric patients versus 44 (range: 19-59) months for adult patients (p = 0.026). Pediatric patients were mostly female (p = 0.003), had symptoms at presentation (p < 0.001), and had a high-stage tumour (p = 0.014) than adult patients. Among the symptomatic patients, gross hematuria was the most common symptom. The median tumour size was not different between groups. Regarding histologic types, pediatric patients had more papillary tumours (p < 0.001), more unclassified tumours (p < 0.001), and fewer clear cell carcinomas (p < 0.001). Five-year cancer-specific survival rates were 85% and 87.4% in pediatric and adult patients, respectively (log rank p = 0.901). Recurrence-free survival was better in adult patients, although this did not reach statistical significance (log rank p = 0.272). This study has several limitations, including its retrospective nature and the relatively small number of pediatric RCC cases.

CONCLUSION

RCC in children is rare and is characterized by features that differ from those in adult RCC. Prognosis did not differ between groups.

Omission of doxorubicin from the treatment of stage II-III, intermediate-risk Wilms' tumour (SIOP WT 2001): an open-label, non-inferiority, randomised controlled trial

BACKGROUND

Before this study started, the standard postoperative chemotherapy regimen for stage II-III Wilms' tumour pretreated with chemotherapy was to include doxorubicin. However, avoidance of doxorubicin-related cardiotoxicity effects is important to improve long-term outcomes for childhood cancers that have excellent prognosis. We aimed to assess whether doxorubicin can be omitted safely from chemotherapy for stage II-III, histological intermediate-risk Wilms' tumour when a newly defined high-risk blastemal subtype was excluded from randomisation.

METHODS

For this international, multicentre, open-label, non-inferiority, phase 3, randomised SIOP WT 2001 trial, we recruited children aged 6 months to 18 years at the time of diagnosis of a primary renal tumour from 251 hospitals in 26 countries who had received 4 weeks of preoperative chemotherapy with vincristine and actinomycin D. Children with stage II-III intermediate-risk Wilms' tumours assessed after delayed nephrectomy were randomly assigned (1:1) by a minimisation technique to receive vincristine 1·5 mg/m(2) at weeks 1-8, 11, 12, 14, 15, 17, 18, 20, 21, 23, 24, 26, and 27, plus actinomycin D 45 μg/kg every 3 weeks from week 2, either with five doses of doxorubicin 50 mg/m(2) given every 6 weeks from week 2 (standard treatment) or without doxorubicin (experimental treatment). The primary endpoint was non-inferiority of event-free survival at 2 years, analysed by intention to treat and a margin of 10%. Assessment of safety and adverse events included systematic monitoring of hepatic toxicity and cardiotoxicity. This trial is registered with EudraCT, number 2007-004591-39, and is closed to new participants.

FINDINGS

Between Nov 1, 2001, and Dec 16, 2009, we recruited 583 patients, 341 with stage II and 242 with stage III tumours, and randomly assigned 291 children to treatment including doxorubicin, and 292 children to treatment excluding doxorubicin. Median follow-up was 60·8 months (IQR 40·8-79·8). 2 year event-free survival was 92·6% (95% CI 89·6-95·7) for treatment including doxorubicin and 88·2% (84·5-92·1) for treatment excluding doxorubicin, a difference of 4·4% (95% CI 0·4-9·3) that did not exceed the predefined 10% margin. 5 year overall survival was 96·5% (94·3-98·8) for treatment including doxorubicin and 95·8% (93·3-98·4) for treatment excluding doxorubicin. Four children died from a treatment-related toxic effect; one (<1%) of 291 receiving treatment including doxorubicin died of sepsis, three (1%) of 292 receiving treatment excluding doxorubicin died of varicella, metabolic seizure, and sepsis during treatment for relapse. 17 patients (3%) had hepatic veno-occlusive disease. Cardiotoxic effects were reported in 15 (5%) of 291 children receiving treatment including doxorubicin. 12 children receiving treatment including doxorubicin, and ten children receiving treatment excluding doxorubicin, died, with the remaining deaths from tumour recurrence.

INTERPRETATION

Doxorubicin does not need to be included in treatment of stage II-III intermediate risk Wilms' tumour when the histological response to preoperative chemotherapy is incorporated into the risk stratification.

FUNDING

See Acknowledgments for funders.

Incidence, Trends, and Survival of Children With Embryonal Tumors

BACKGROUND

Central nervous system (CNS) and non-CNS embryonal tumors occur principally in children and are rarely seen in adults. The incidence rates for rare entities such as atypical teratoid/rhabdoid tumors (AT/RT) or primitive neuroectodermal tumors in the CNS are rarely published. Incidence rates for certain subgroups, such as hepatoblastomas, have been increasing in some countries.

METHODS

Data of 8337 embryonal tumors, registered in children (0-14 years) between 1991 and 2012 (for AT/RT 2000-2012) in the population-based German Childhood Cancer Registry with complete national coverage were analyzed for incidence rates, time trends, and survival.

RESULTS

For most entities, the incidence rates were the highest for children <1 year. An important exception was medulloblastomas, which occurred mainly in 1- to 9-year-olds. Neuroblastomas and ganglioneuroblastomas as well as Wilms tumors (nephroblastomas) had the highest age standardized incidence rates (13.7 and 9.4 per million, respectively). A statistically significant increasing trend for hepatoblastomas (annual average percent change 4.6%) was detected. The survival probabilities varied between the diagnostic groups: primitive neuroectodermal tumors and AT/RT had the lowest and retinoblastomas the highest. The survival was dependent on the age at diagnosis, the most extreme examples being neuroblastomas, for which the survival probability declined steeply for children ≥1 year and medulloblastomas, for which the highest survival was seen for 10- to 14-year-olds.

CONCLUSIONS

This study presents a comprehensive overview of pediatric embryonal tumors from a well-established, complete nationwide cancer registry. Significant increasing trend for hepatoblastomas was detected for the first time in Europe.

A multi-Gaussian model for apparent diffusion coefficient histogram analysis of Wilms' tumour subtype and response to chemotherapy

Wilms' tumours (WTs) are large heterogeneous tumours, which typically consist of a mixture of histological cell types, together with regions of chemotherapy-induced regressive change and necrosis. The predominant cell type in a WT is assessed histologically following nephrectomy, and used to assess the tumour subtype and potential risk. The purpose of this study was to develop a mathematical model to identify subregions within WTs with distinct cellular environments in vivo, determined using apparent diffusion coefficient (ADC) values from diffusion-weighted imaging (DWI). We recorded the WT subtype from the histopathology of 32 tumours resected in patients who received DWI prior to surgery after pre-operative chemotherapy had been administered. In 23 of these tumours, DWI data were also available prior to chemotherapy. Histograms of ADC values were analysed using a multi-Gaussian model fitting procedure, which identified 'subpopulations' with distinct cellular environments within the tumour volume. The mean and lower quartile ADC values of the predominant viable tissue subpopulation (ADC(1MEAN), ADC(1LQ)), together with the same parameters from the entire tumour volume (ADC(0MEAN), ADC(0LQ)), were tested as predictors of WT subtype. ADC(1LQ) from the multi-Gaussian model was the most effective parameter for the stratification of WT subtype, with significantly lower values observed in high-risk blastemal-type WTs compared with intermediate-risk stromal, regressive and mixed-type WTs (p < 0.05). No significant difference in ADC(1LQ) was found between blastemal-type and intermediate-risk epithelial-type WTs. The predominant viable tissue subpopulation in every stromal-type WT underwent a positive shift in ADC(1MEAN) after chemotherapy. Our results suggest that our multi-Gaussian model is a useful tool for differentiating distinct cellular regions within WTs, which helps to identify the predominant histological cell type in the tumour in vivo. This shows potential for improving the risk-based stratification of patients at an early stage, and for guiding biopsies to target the most malignant part of the tumour.

A case of chromophobe renal cell carcinoma in a 12-year-old girl

Renal cell carcinoma (RCC) accounts for only 2-6 % of pediatric renal tumors. Chromophobe RCC is very rare in pediatric patients, with only a few cases reported. A 12-year-old girl who had abdominal and left flank pain visited the pediatric clinic of a local hospital. A uniformly enhanced tumor measuring 2.5 cm × 2.3 cm was found on computed tomography. On magnetic resonance imaging, T2-weighted images showed a solid tumor with hyperintensity suggesting intratumoral necrosis. We considered RCC and Wilms' tumor as differential diagnoses, but we could not reach a definitive diagnosis from the radiographic findings. We then performed right partial nephrectomy with regional lymph node dissection. The histopathological diagnosis was pT1aN0 chromophobe RCC. After the surgery, no recurrence has been observed for 15 months.

Neuroblastoma and nephroblastoma: a radiological review

Neuroblastoma (NBL) is the most common extra-cranial tumour in childhood. It can present as an abdominal mass, but is usually metastatic at diagnosis so the symptomatology can be varied. Nephroblastoma, also more commonly known as a Wilms tumour, is the commonest renal tumour in childhood and more typically presents as abdominal pathology with few constitutional symptoms, although rarely haematuria can be a presenting feature. The pathophysiology and clinical aspects of both tumours including associated risk factors and pathologies are discussed. Oncogenetics and chromosomal abnormalities are increasingly recognised as important prognostic indicators and their impact on initial management is considered. Imaging plays a pivotal role in terms of diagnosis and recent imaging advances mean that radiology has an increasingly crucial role in the management pathway. The use of image defined risk factors in neuroblastoma has begun to dramatically change how this tumour is characterised pre-operatively. The National Wilms Tumour Study Group have comprehensively staged Wilms tumours and this is reviewed as it impacts significantly on management. The use of contrast-enhanced MRI and diffusion-weighted sequences have further served to augment the information available to the clinical team during initial assessment of both neuroblastomas and Wilms tumours. The differences in management strategies are outlined. This paper therefore aims to provide a comprehensive update on these two common paediatric tumours with a particular emphasis on the current crucial role played by imaging.

Wilms tumor: experience of a hospital in southern Brazil

BACKGROUND

Wilms tumor (WT) is the most common renal malignancy of childhood. The aim of this study was to verify the epidemiological profile and prognosis of a sample of patients from Brazil and compare them to similar data from other Latin American studies.

METHOD

The sample consisted of consecutive patients diagnosed with WT in an oncohematology service of a referral hospital in Southern Brazil, between 1989 and 2009. Clinical, radiological, pathological and survival data were collected from the medical records. Analysis was done using Excel and SPSS version 18.0. The significance level was set at P < 0.05.

RESULTS

The final sample consisted of 45 patients. The male/female ratio was 1.25:1. Mean age at diagnosis was 43.9 months and all patients were of European descent. Thirty-three patients (73.3%) had both signs/symptoms of abdominal mass and hypertension. Malformation was observed in nine patients (20%) and there was one case of Fanconi's anemia (2.2%). Three patients had bilateral disease (6.7%). The majority of patients had stage III and IV (62.2%). Patients with malformation had an earlier age at diagnosis (P = 0.018) and a higher prevalence of bilateral disease (P = 0.044). Overall survival was 75%. Age at diagnosis was the only significant independent predictor associated with death.

CONCLUSION

Death is closely related to late diagnosis in WT. Oncologic services should also be concerned about morbidity caused by therapeutic options in cases of late diagnosis, and the consequences for quality of life.

WARM N COLD: malignant and benign renal tumors in children

Although Wilms tumor is the most common renal malignancy in children, the differential diagnosis is extensive and includes both malignant and benign disorders. We present a simple mnemonic-WARM N COLD, to aid in remembering these diverse tumors. Imaging clues including age of the patient, associated disease or syndrome as well as salient imaging characteristics such as bilaterality, and type or presence of metastasis are also presented and can help differentiate between these renal tumors of childhood.

Wilms' tumor: biology, diagnosis and treatment

Wilms' tumor is the commonest renal tumor of childhood affecting one in 10,000 children. It is also one of the successes of paediatric oncology with long term survival above 90% for localised disease and 75% for metastatic disease. Successful management of Wilms' tumor necessitates meticulous attention to correct staging of the tumor and a collaborative effort between paediatric oncologists, specialist surgeons, radiologists, pathologists, and radiation oncologists. Although current treatment protocols are based on risk assignment to minimise toxicity for low risk patients and improve outcomes for those with high risk disease, challenges remain in identifying novel molecular, histological and clinical risk factors for stratification of treatment intensity. Knowledge about Wilms' tumor biology and treatment is evolving rapidly and remains a paradigm for multimodal malignancy treatment. Future efforts will focus on the use of biomarkers to improve risk stratification and the introduction of newer molecularly targeted therapies that will minimise toxicity and improve the outcomes for patients with unfavourable histology and recurrent disease. The aim of this article is to summarise advances in our understanding of the biology of Wilms' tumor and to describe the current approaches to clinical management of patients.

Defects in the DNA mismatch repair system do not contribute to the development of childhood wilms tumors

Wilms tumor is the most common childhood renal malignancy. Most Wilms tumors occur sporadically, whereas a genetic predisposition is described in 9-19% of the Wilms tumor patients. In addition to constitutional aberrations, somatic aberrations in multiple genetic loci such as WT1, WT2 or locus 11p15.5, CTNNB1, WTX, TP53, FBXW7, and MYCN have also been linked to Wilms tumorigenesis. In sporadic Wilms tumors, however, the driving somatic genetic aberrations need to be further unraveled. Therefore, it is necessary to obtain more insight into other underlying mechanisms. Little is known about the role of defects in the DNA mismatch repair system in the etiology of Wilms tumors. To detect mismatch repair deficiency in a full cohort of Wilms tumor patients, we combined immunohistochemistry for the expression of mismatch repair proteins and microsatellite instability (MSI) analysis by a fluorescent multiplex polymerase chain reaction-based assay. Of the 121 Wilms tumor patients treated between 1987 and 2010 in our institution, 100 samples from 97 patients were available for analysis. Nuclear staining for MLH1, MSH2, MSH6, and PMS2 proteins was present in all 100 Wilms tumor samples. No pattern of MSI was found in any of the 100 investigated Wilms tumor samples. The matching results of normal expression of the mismatch repair proteins detected by immunohistochemistry and the absence of MSI by DNA analysis in 100 Wilms tumor samples lead us to conclude that defects in the DNA mismatch repair system do not play a significant role in the development of Wilms tumors.

Metastatic renal cell carcinoma in children and adolescents: a 30-year unsuccessful story

BACKGROUND

Because of the rare occurrence of renal cell carcinoma (RCC) among children very little is known about this malignancy in pediatric age. We aimed adding knowledge on the clinical characteristics and outcome of metastatic (m) RCC in children and adolescents.

PATIENTS AND METHODS

The series included 14 stage 4 RCC patients with a median age at diagnosis of 155.5 months, observed at the Italian Pediatric Hematology and Oncology Association (AIEOP) centers from January 1973 to November 2010. We were able to reevaluate histopatology of 11 out of the 14 patients and perform immunostaining for TFE3 in 9 out of the 11 patients.

RESULTS

Of the 14 patients under study, 5 (3 girls) had a translocation morphology TFE+ RCC, 2 were reassigned as papillary type 1 or 2, respectively, 2 tumor specimens with primary clear cell histology had confirmed the initial histologic diagnosis, and 2-whose biopsy specimen was insufficient-had the diagnosis of RCC not further specified with subtyping. In the remaining 3 cases, the initial diagnosis of clear cell carcinoma was left. Overall, 6 patients received chemotherapy, 9 immunotherapy, and 2 adjuvant antiangiogenic therapy. Overall, 11 patients (78.5%) never achieved complete remission and died from progressive disease 1 to 16 months after diagnosis (median overall survival 5.5 mo). Three patients, 2 of whom received adjuvant antiangiogenic therapy, relapsed to lung at 3, 6, and 8 months after diagnosis, and died 18, 32, and 33 months after diagnosis, respectively.

CONCLUSIONS

Despite their possibly different biology, childhood and adult mRCC seems to be sharing comparable outcomes. Because of the very low incidence of mRCC (about 20%) in children and adolescents, an international pediatric cooperation to address biological studies and assess the novel targeted approaches is needed.

Long-term graft-versus-tumor effect following reduced intensity hematopoietic stem cell transplantation in a child with metastatic renal cell carcinoma

Pediatric renal cell carcinoma (RCC) is rare and different from adult RCC. Although target agents have recently been introduced, allogeneic hematopoietic stem cell transplantation exploiting graft-versus-tumor effect still remains an important treatment option for metastatic RCC. A 2-year-old male with RCC developed hepatic metastases 6 months following radical nephrectomy and subsequent cytokine therapy. Allogeneic reduced-intensity stem cell transplantation (RIST) with early withdrawal of immunosuppression and delayed donor lymphocyte infusions was performed. A second transplantation was undertaken following marrow aplasia. Now he remains progression-free with regression of hepatic metastases 5.7 years after RIST, along with complete donor chimerism.

Incidence of abdominal tumors in syndromic and idiopathic hemihypertrophy/isolated hemihyperplasia

BACKGROUND

There is a reported increased risk of intra-abdominal tumors in children with both syndromic (SH) and isolated idiopathic hemihyperplasia (IH). Recommendations for tumor surveillance have been made, although there is no consensus for frequency and duration of screening. Our objective was to review the incidence of abdominal neoplasms in our pediatric population with SH and IH.

METHODS

We reviewed the diagnostic criteria, imaging findings, and any associated syndrome in all patients diagnosed with hemihypertrophy over a 10-year period.

RESULTS

One of 10 patients with SH, a child with Beckwith-Wiedemann syndrome, developed a hepatoblastoma resulting in a 10% tumor incidence in patients with SH. Three of the 250 (1.2%) children with IH developed an abdominal neoplasm. One was diagnosed with adrenal carcinoma and the other 2 with Wilms tumor.

CONCLUSIONS

We found an increased incidence of abdominal tumors in both SH and IH, however, our incidence of tumors with IH is lower than earlier reported studies. On the basis of this lower 1.2% incidence, the current literature on IH and available molecular genetic testing, it is reasonable to recommend referral of these patients to a clinical geneticist to identify subgroups with a higher risk for tumor development that are more likely to benefit from routine imaging surveillance.

LEVEL OF EVIDENCE

II-Retrospective study.

Frequency of WT1 and 11p15 constitutional aberrations and phenotypic correlation in childhood Wilms tumour patients

INTRODUCTION

In 9-17% of Wilms tumour patients a predisposing syndrome is present, in particular WT1-associated syndromes and overgrowth syndromes. Constitutional WT1 mutations or epigenetic changes on chromosome 11p15 have also been described in Wilms tumour patients without phenotypic abnormalities. Thus, the absence of phenotypic abnormalities does not exclude the presence of a genetic predisposition, suggesting that more Wilms tumour patients may have a constitutional abnormality. Therefore, we investigated the frequency of constitutional aberrations in combination with phenotype.

PATIENTS & METHODS

Clinical genetic assessment, as well as molecular analysis of WT1 and locus 11p15 was offered to a single-centre cohort of 109 childhood Wilms tumour patients.

RESULTS

Twelve patients (11%) had a WT1 aberration and eight patients (8%) had an 11p15 aberration. Of the 12 patients with a WT1 aberration, four had WAGR syndrome (Wilms tumor, aniridia, genitourinary malformations and mental retardation), one had Denys-Drash syndrome, four had genitourinary anomalies without other syndromic features and three had bilateral disease with stromal-predominant histology at young age without congenital anomalies. Of the eight patients with an 11p15 aberration, four had Beckwith-Wiedemann syndrome (BWS), two had minor features of BWS and two had no stigmata of BWS or hemihypertrophy.

CONCLUSION

Constitutional WT1 or 11p15 aberrations are frequent in Wilms tumour patients and careful clinical assessment can identify the majority of these patients. Therefore, we would recommend offering clinical genetic counselling to all Wilms tumour patients, as well as molecular analysis to patients with clinical signs of a syndrome or with features that may indicate a constitutional WT1 or 11p15 aberration.

Embryonal cancers in Europe

Embryonal cancers are a heterogeneous group of rare cancers which mainly occur in children and adolescents. The aim of the present study was to estimate the burden (incidence, prevalence, survival and proportion of cured) for the principal embryonal cancers in Europe (EU27), using population-based data from cancer registries (CRs) participating in RARECARE. We identified 3322 cases diagnosed from 1995 to 2002 (latest period for which data are available): 44% neuroblastoma, 35% nephroblastoma, 13% retinoblastoma and 6% hepatoblastoma. Very few cases of pulmonary blastoma (43 cases) and pancreatoblastoma (seven cases) were diagnosed. About 2000 new embryonal cancers were estimated every year in EU27, for an annual incidence rate of 4 per million (1.8 neuroblastoma, 1.4 nephroblastoma, and 0.5 retinoblastoma); 91% of cases occurred in patients under 15 years. Five-year relative survival for all embryonal cancers was 80% (99% retinoblastoma, 90% nephroblastoma, 71% hepatoblastoma and 68% neuroblastoma). Overall survival was lower in adolescents and adults than in those under 15 years. The cure rate was estimated at 80%. Slightly less than 40,000 persons were estimated alive in EU27 with a diagnosis of embryonal cancer in 2008. Nephroblastoma was the most prevalent (18,150 cases in EU27), followed by neuroblastoma (12,100), retinoblastoma (5200), hepatoblastoma (2700) and pulmonary blastoma (614). This is the first study to delineate the embryonal cancer burden in Europe by age, sex and European region. Survival/cure rate is generally high, but there are considerable gaps in our understanding of the natural histories of these rare diseases particularly in adults.

Dependence of Wilms tumor cells on signaling through insulin-like growth factor 1 in an orthotopic xenograft model targetable by specific receptor inhibition

We have previously demonstrated an increased DNA copy number and expression of IGF1R to be associated with poor outcome in Wilms tumors. We have now tested whether inhibiting this receptor may be a useful therapeutic strategy by using a panel of Wilms tumor cell lines. Both genetic and pharmacological targeting resulted in inhibition of downstream signaling through PI3 and MAP kinases, G(1) cell cycle arrest, and cell death, with drug efficacy dependent on the levels of phosphorylated IGF1R. These effects were further associated with specific gene expression signatures reflecting pathway inhibition, and conferred synergistic chemosensitisation to doxorubicin and topotecan. In the in vivo setting, s.c. xenografts of WiT49 cells resembled malignant rhabdoid tumors rather than Wilms tumors. Treatment with an IGF1R inhibitor (NVP-AEW541) showed no discernable antitumor activity and no downstream pathway inactivation. By contrast, Wilms tumor cells established orthotopically within the kidney were histologically accurate and exhibited significantly elevated insulin-like growth factor-mediated signaling, and growth was significantly reduced on treatment with NVP-AEW541 in parallel with signaling pathway ablation. As a result of the paracrine effects of enhanced IGF2 expression in Wilms tumor, this disease may be acutely dependent on signaling through the IGF1 receptor, and thus treatment strategies aimed at its inhibition may be useful in the clinic. Such efficacy may be missed if only standard ectopic models are considered as a result of an imperfect recapitulation of the specific tumor microenvironment.

Wilms tumor

Significant improvement has been made in the treatment of children with Wilms tumor. New protocols are in place designed to maintain a high rate of cure for these patients while minimizing toxicity, based on refinement of the risk-stratification system.

Retinoic acid pathway activity in Wilms tumors and characterization of biological responses in vitro

BACKGROUND

Wilms tumor (WT) is one of the most common malignancies in childhood. With current therapy protocols up to 90% of patients can be cured, but there is still a need to improve therapy for patients with aggressive WT and to reduce treatment intensity where possible. Prior data suggested a deregulation of the retinoic acid (RA) signaling pathway in high-risk WT, but its mode of action remained unclear.

RESULTS

The association of retinoid signaling and clinical parameters could be validated in a large independent tumor set, but its relevance in primary nephrectomy tumors from very young children may be different. Reduced RA pathway activity and MYCN overexpression were found in high risk tumors as opposed to tumors with low/intermediate risk, suggesting a beneficial impact of RA especially on advanced WT. To search for possible modes of action of retinoids as novel therapeutic options, primary tumor cell cultures were treated in vitro with all-trans-RA (ATRA), 9cis-RA, fenretinide and combinations of retinoids and a histone deacetylase (HDAC) inhibitor. Genes deregulated in high risk tumors showed opposite changes upon treatment suggesting a positive effect of retinoids. 6/7 primary cultures tested reduced proliferation, irrespective of prior RA signaling levels. The only variant culture was derived from mesoblastic nephroma, a distinct childhood kidney neoplasm. Retinoid/HDAC inhibitor combinations provided no synergistic effect. ATRA and 9cis-RA induced morphological changes suggestive of differentiation, while fenretinide induced apoptosis in several cultures tested. Microarray analysis of ATRA treated WT cells revealed differential expression of many genes involved in extracellular matrix formation and osteogenic, neuronal or muscle differentiation. The effects documented appear to be reversible upon drug withdrawal, however.

CONCLUSIONS

Altered retinoic acid signaling has been validated especially in high risk Wilms tumors. In vitro testing of primary tumor cultures provided clear evidence of a potential utility of retinoids in Wilms tumor treatment based on the analysis of gene expression, proliferation, differentiation and apoptosis.

Continuing response to subsequent treatment lines with tyrosine kinase inhibitors in an adolescent with metastatic renal cell carcinoma

A 14-year-old girl with metastatic renal cell carcinoma was treated with nephrectomy, interferon, and several lines of the targeted agents sorafenib, bevacizumab, sunitinib, and everolimus, either alone or in combination. Treatment was well tolerated, but the patient developed hypothyroidism and significant hypertension with bevacizumab and sunitinib. She responded to all agents and was given radiation treatment twice at the time of symptomatic disease progression; she died 33 months from diagnosis.

Birth characteristics and Wilms tumors in children in the Nordic countries: a register-based case-control study

Little is known about causes of Wilms tumor. Because of the young age at diagnosis, several studies have looked at various birth characteristics. We conducted a registry-based case-control study involving 690 cases of Wilms tumor aged 0-14 years, occurring in Denmark, Finland, Norway or Sweden during 1985-2006, individually matched to five controls drawn randomly from the Nordic childhood population. Information on birth characteristics was obtained from the population-based medical birth registries. We estimated odds ratios (ORs) and 95% confidence intervals (CIs) using conditional logistic regression analysis. We observed a distinct association between Wilms tumor and high birth weight (≥4 kg) for girls (OR 1.97, CI 1.50-2.59) but not for boys (1.04, 0.78-1.38); overall, the OR was 1.43 (1.17-1.74). Among girls, risk increased by 28% (15-42%) per 500 g increase in birth weight. Large-for-gestational age girls also had a higher risk (2.48, 1.51-4.05), whereas no effect was seen for boys (1.12, 0.60-2.07). An association was seen with Apgar score at 5 min < 7 for both sexes combined (5.13, 2.55-10.3). ORs close to unity were seen for parental age and birth order. In our large-scale, registry-based study, we confirmed earlier observations of an association between high birth weight and risk of Wilms tumor, but we found an effect only in girls. The higher risk of infants with low Apgar score might reflect hypoxia causing cell damage, adverse side effects of neonatal treatment or reverse causation as low Apgar score might indicate the presence of a tumor.

Renal tumors in children aged 10-16 Years: a report from the United Kingdom Children's Cancer and Leukaemia Group

Wilms tumor is the most common renal tumor of childhood. However, other epithelial, mesenchymal, and neuroectodermal neoplasms may also arise in the kidney during childhood, several of which show specific age distributions; in the 1st year of life, mesoblastic nephroma and rhabdoid tumor are more common, whereas renal cell carcinoma, primitive neuroectodermal tumor, and anaplastic Wilms tumors are relatively more frequent in older children and adolescents. The aim of this study is to describe the spectrum of renal tumors in children aged 10-16 years using data from 1492 patients registered in the UK Wilms Tumour 3 Trial (1991-2001) and International Society of Paediatric Oncology Wilms Tumour Trial 2001 (2002-2008) clinical trials of renal tumors in childhood. There were 67 (4.6%) tumors in children aged 10-16 years: 50 Wilms tumors (74.6%), 10 (14.9%) renal cell carcinomas, 3 (4.5%) renal medullary carcinomas, 2 (3%) primitive neuroectodermal tumors, 1 clear cell sarcoma of kidney, and 1 desmoplastic small round cell tumor. Fourteen percent of the Wilms tumors in this age group had diffuse anaplasia. Among the 10 renal cell carcinomas, 4 were associated with t(Xp-11.2), 3 were of papillary type II, 1 was papillary type I, 1 was clear cell type, and 1 was unclassified. Five-year overall survival for Wilms tumor was 63% (43% for anaplastic tumors), significantly lower than reported overall survival for all pediatric Wilms tumors. Only 40% of patients with renal cell carcinoma survived, and all patients with other tumors died.

Renal cell carcinoma in children and adolescents

Although rare in children and adolescents, renal cell carcinomas (RCCs) raise important questions concerning the best treatment approach and accurate pathologic classification. The differences emerging between childhood and adulthood RCC probably prevent any direct generalized application of therapies to children that are validated for adults. The translocation type of RCC, which forms a distinct category characterized by translocations involving Xp11.2 or, less frequently, 6p21, has recently emerged as the predominant type of RCC in children and adolescents, whereas it is rarely diagnosed in adults. This new finding emphasizes how important it is to prospectively classify RCCs in children with standardized 'modern' diagnoses. The standard cornerstone of therapy for RCC in children and adolescents remains radical nephrectomy. Nephron-sparing surgery is currently recommended in adults for selected small-volume tumors, but additional data are needed before this experience can be extensively transferred to the pediatric population. The therapeutic value of complete retroperitoneal lymph node dissection is still controversial, especially in patients without suspected nodal involvement, be they adults or children. The backbone of systemic therapies for adult RCC has recently been changed by the introduction of drugs designed to target tumor-related angiogenesis and signal transduction. It is worth noting that the largest clinical efficacy trials on targeted molecules have been conducted on clear-cell RCC. While targeted drugs have become the standard of care for adult metastatic RCC, there are currently no published reports on their role in children, and their use should be considered for patients with unresectable metastatic or advanced-stage RCC. On the other hand, the utility of targeted therapies in the adjuvant setting remains to be seen for both adults and children.

Pediatric Renal Cell Carcinoma

Renal cell carcinomas are rare in children, and they show significant differences in their histology and pathogenesis when compared to those common in adults. The most common subtypes seen preferentially in children are the translocation-associated tumors, papillary renal cell carcinoma, renal medullary carcinoma, and oncocytic renal cell carcinoma following neuroblastoma. The histological diagnosis of renal cell carcinoma is made difficult by the considerable heterogeneity within and overlap between each of the above subtypes and by similarities to other pediatric renal neoplasms. While no effective therapies have yet been identified, there is considerable promise that the new Children's Oncology Group protocol will provide knowledge that will guide the future therapy of these lesions.

Wilms' tumour: a systematic review of risk factors and meta-analysis

Wilms' tumour comprises 95% of all renal cancers among children less than 15 years of age. The purpose of this review is to examine the existing literature on perinatal and environmental risk factors for Wilms' tumour. A search for epidemiological studies that examined risk factors for Wilms' tumour was undertaken in Medline, LILACS, ISI Web of Science and Dissertation Abstracts. A total of 37 studies, including 14 cohort, 21 case-control and 2 case-cohort studies, were identified that examined environmental and perinatal risk factors. Most studies were from Western Europe and North America, and among case-control studies, 16 used randomly selected population-based controls. We observed a significantly increased risk of Wilms' tumour with maternal exposure to pesticides prior to the child's birth (OR = 1.37 [95% CI 1.09, 1.73]), high birthweight (OR = 1.36 [95% CI 1.12, 1.64]) and preterm birth (OR = 1.44 [95% CI 1.14, 1.81]), although the results regarding pesticide exposure may be subject to publication bias (Egger's test, P = 0.09). Further analyses to adjust for the heterogeneity in the results for high birthweight and preterm birth did not statistically change the significance of the results. Additionally, an increased though not statistically significant risk of Wilms' tumour was associated with maternal hypertension (OR = 1.30 [95% CI 0.99, 1.72]), and, compared with the first born, being a second or later birth was associated with a significantly decreased risk (OR = 0.82 [95% CI 0.71, 0.95]). This review suggests a role for several perinatal and environmental risk factors in the aetiology of Wilms' tumour.

Childhood cancer survival: a report from the United Kingdom Childhood Cancer Study

BACKGROUND

Improvements in diagnostic approaches and refinements to treatment protocols have resulted in 5-year survival levels above 70% for children diagnosed with cancer in economically developed parts of the world. For some cancers, including leukaemia and tumours of the central nervous system, age and sex have been identified as important prognostic indicators.

METHODS

We examined long-term survival, and affects of age and sex, in a population-based case-control study. Children (0-14 years) newly diagnosed with cancer were ascertained between 1991 and 1996 (n=4433). Follow-up information was obtained from the National Health Service (NHS) Information Centre for Health and Social Care which records all exits from the NHS including deaths.

RESULTS

For all cancer diagnoses combined, 5-year survival was 72.7% dropping to 67.9% at 15 years. As expected, survival differed between diagnostic subtypes ranging from 38.1% for intracranial embryonal tumours to 96.2% for Hodgkin lymphoma. Compared to girls, boys diagnosed with acute lymphoblastic leukaemia were at a higher risk of dying (RR=1.26, 95% CI 1.03-1.53), whereas boys diagnosed with an intracranial embryonal tumour were at a lower risk of death (RR=0.63, 95% CI 0.43-0.91).

CONCLUSION

Our initial findings are consistent with previous reports, and highlight the importance of considering differences by age and sex. The completeness and population-based nature of the original case-control study is an important feature which will provide the basis for future more detailed investigations linking disease determinants to outcome.

Malignant tumours of the kidney: imaging strategy

Primitive malignant renal tumours comprise 6% of all childhood cancers. Wilms tumour (WT) or nephroblastoma is the most frequent type accounting for more than 90%. Imaging alone cannot differentiate between these tumours with certainty but it plays an important role in screening, diagnostic workup, assessment of therapy response, preoperative evaluation and follow-up. The outcome of WT after therapy is excellent with an overall survival around 90%. In tumours such as those where the outcome is extremely good, focus can be shifted to a risk-based stratification to maintain excellent outcome in children with low risk tumours while improving quality of life and decreasing toxicity and costs. This review will discuss the imaging issues for WT from the European perspective and briefly discuss the characteristics of other malignant renal tumours occurring in children and new imaging techniques with potential in this matter.

Clear cell sarcoma of the kidney in children: experience in a developing country

INTRODUCTION

Clear cell sarcoma of the kidney (CCSK) is a rare tumour comprising 4% of primary renal tumours in children. It has a unique constellation of chromosomal and molecular features and should no longer be viewed as an unfavourable histological variant of Wilms tumour. Little is known of its clinical presentation and pathological profile in children living in a developing country.

AIM

To describe the clinical and pathological features of CCSK in children in our practice and to identify factors contributing to poor patient outcomes.

METHOD

A retrospective review of patients with a confirmed diagnosis of CCSK who presented for treatment at a single institution between 1990 and 2008.

RESULTS

14 patients fulfilled the inception criteria. They represented 4% of 356 patients presenting with primary renal tumours during the review period. Clinical and radiological features were indistinguishable from Wilms tumour. Tumours were large (Mean mass 1.4 kg; median 0.9 kg) and metastases were common (42%). Lung and lymph node metastases were more common than skeletal disease. Co-morbidity, particularly hypertension (64%) was common. Initial diagnosis by needle biopsy was correct in only two of seven patients (29%) leading to inappropriate neoadjuvant chemotherapy. Overall survival is poor with 57% of patients alive and disease free from 1 to 7 years off treatment.

CONCLUSION

In a developing country, CCSK is rare and clinically and radiologically indistinguishable from Wilms tumour. Associated hypertension is common. Pretreatment diagnosis is difficult and sampling errors using needle biopsies may be unavoidable. Treatment results are poor and, given the propensity for late recurrence in CCSK, may not be sustained.

A rare case of simultaneous occurrence of Wilms' tumor in the left kidney and the bladder

Wilms' tumor is the most common malignant solid tumor of the kidneys in children. Extrarenal Wilms' tumor is extremely rare. Herein, we report an 8-month-old boy with a chief complaint of frequent micturition and dysuria for 10 days. Physical examination and ultrasonography evaluation revealed simultaneous involvement of neoplasms in the left kidney and the bladder. Following excision of the masses, both were identified as Wilms' tumor by histopathology and immunohistochemistry. The two neoplasms are presumed to have developed independently because of the different pathological manifestation.

Nuclear accumulation of beta-catenin protein indicates activation of wnt signaling in chemically induced rat nephroblastomas

Aberrant wnt signaling caused by mutations in CTNNB1 occurs in about 15% of Wilms tumors, and these mutations appear to be dependent on the concomitant mutational inactivation of the zinc-finger protein WT1. Nuclear beta-catenin protein, a substitute marker of active wnt signaling, has been detected in an even higher proportion (>50%) of Wilms tumors, suggesting alternative genetic pathways leading to beta-catenin activation. Thus, targeting wnt signaling may become an important future therapeutic strategy in Wilms tumor patients. Currently, chemically induced rat nephroblastomas provide the only available rodent model for this tumor. To determine the contribution of active wnt signaling in this model, we investigated 24 chemically induced rat nephroblastomas for beta-catenin protein expression and for Ctnnb1 and WT1 mutations. Immunohistochemistry showed focal strong nuclear accumulation of beta-catenin protein in 18 of 24 tumors, although in a heterogenous pattern. Blastemal and mesenchymal compartments displayed nuclear-positive cells more frequently than areas of epithelial differentiation. Interestingly, we found no mutation of exon 3 of Ctnnb1 and no mutation within the zinc-finger region of WT1 in any of the 24 tumors analyzed. In conclusion, our findings suggest activation of wnt signaling in the majority (63%) of chemically induced rat nephroblastomas. Nuclear expression of beta-catenin in the absence of Ctnnb1 mutations implies, however, alternate mutational targets in rat nephroblastomas.

Wilms' tumor

PURPOSE OF REVIEW

Wilms' tumor accounts for nearly 6% of all pediatric cancers and more than 95% of all kidney tumors in children. Fortunately, survival for patients with Wilms' tumor is generally excellent. This review will outline the results of prior clinical trials that have led to this excellent outcome and how information gleaned from these trials has led to the development of the current series of clinical trials for the management of children with Wilms' tumor.

RECENT FINDINGS

Tumor stage and histologic subtype have long been recognized as important prognostic factors in Wilms' tumor. More recent evidence suggests that, in certain instances, patient age, tumor size, response to therapy, and genetic abnormalities, specifically the loss of genetic material on chromosomes 1p and 16q, provide additional prognostic information. These factors have, therefore, been incorporated into a new risk stratification system that is currently being used to assign patients with Wilms' tumor to specific protocol-based therapies.

SUMMARY

Survival for patients with Wilms' tumor when considered as a whole, once less than 30%, is currently greater than 90%, with this dramatic improvement being due, in part, to the systematic manner in which the approach to therapy has evolved. Further refinement in therapy is being undertaken, with the current trials aiming to maintain the excellent survival for children being treated for Wilms' tumor, while minimizing therapy-related toxicity.

Renal cell carcinoma in the pediatric population: Results from the California Cancer Registry

BACKGROUND

Renal cell carcinoma (RCC) is a rare disease in children and adolescents. This study aimed to review epidemiologic characteristics and survival for pediatric RCC patients using a large, population-based database.

PROCEDURE

The California Cancer Registry (CCR) was reviewed from 1988 to 2004. All cases of RCC in patients younger than 21 years were identified and annual age-adjusted incidence rates were determined for the overall population and subdivided by ethnicity. Tumors were classified by stage and grade, and actuarial mortality rates were calculated.

RESULTS

From 1988 to 2004, 43 cases of RCC were identified in patients younger than 21 years, accounting for 4.3% of all renal tumors in this age group. The overall annual age-adjusted incidence was 0.01/100,000 with the tumor more common in non-Hispanic blacks (0.03/100,000) compared to non-Hispanic whites (0.01/100,000), Hispanics (<0.01/100,000), and non-Hispanic Asians/Pacific Islanders (<0.01/100,000). The mean age at presentation was 15.4 years (SD 4.03, SE 0.615). RCC was identified more frequently in females (58.14%). At the time of presentation, 53.49% of tumors were localized, 20.93% were regionally advanced, and 25.58% were metastatic. The observed actuarial survival at 5 and 10 years was 61% (+/-15.7%).

CONCLUSION

Pediatric RCC is an uncommon and aggressive tumor that occurs most frequently in children in the second decade of life, more often in females and blacks. The epidemiological characteristics of this tumor differ from adult RCC and Wilms tumor, suggesting its distinctive biology and potential need for alternative treatment strategies.

High-resolution molecular cytogenetic analysis of Wilms tumors highlights diagnostic difficulties among small round cell kidney tumors

Many solid tumors exhibit characteristic gene fusions, which are reflected by balanced translocations at the cytogenetic level. These changes might be useful diagnostic and prognostic tools. In Wilms tumor (WT, nephroblastoma) no fusions genes or recurrent balanced translocations have been described thus far. To screen for cryptic balanced translocations, we have analyzed 17 renal neoplasms, histopathologically classified as WT, by a combination of G-banding, multicolor FISH, and subtelomeric FISH. This approach revealed several submicroscopic chromosomal aberrations and three different seemingly balanced translocations, resulting in a heterozygous deletion of HACE1, an EWSR1/ERG fusion, and an EWSR1/FLI1 fusion, respectively. As EWSR1 rearrangements are known to be a characteristic of Ewing tumors (ET), our findings illustrate the diagnostic problems regarding small cell kidney tumors and strongly argue for the need of adjuvant diagnostic techniques in this group of neoplasms. In summary, our genomic screening approach proved efficient in finding structural chromosomal aberrations. The fact that no recurrent translocations were found in the WTs of this study argues against the presence of a frequent pathognomonic translocation in this disease entity.

Abdominal cancer during early childhood: a dosimetric comparison of proton beams to standard and advanced photon radiotherapy

PURPOSE

Evaluation of dosimetric benefits of advanced radiotherapy techniques for the treatment of abdominal lesions during early childhood.

PATIENTS AND METHODS

Treatment planning was performed for five Neuroblastoma (NBL) and four Wilms Tumor (WT) patients. Opposing fields (2F), photon intensity modulated radiotherapy (IMXT) and two proton techniques (passively scattered (PT) and scanned beams (IMPT)) were considered. Averaged dose-volume histograms, associated dosimetric parameters and a radiobiological model for the estimation of the therapy related carcinogenic effect were evaluated.

RESULTS

With respect to the 2F technique, both proton techniques enabled to reduce mean liver and kidney dose by 40-60%; Organ fractions irradiated at the level of the tolerance dose were reduced by 65% for kidneys and 75% for the liver in NBL patients and by additional 10% for WT patients. IMXT enabled to reduce parameters related to the steep high-dose gradient, e.g., V(15Gy) for the kidneys was reduced by a factor 2-3 compared to 2F. V(12Gy) was reduced by 40% in the liver. On the other side, the improvement of those parameters characterizing the low isodose domain was limited for IMXT. The risk for radiation-induced secondary cancer was doubled for IMXT and even more increased for PT if secondary neutrons were taken into account, while this risk remained the same or was reduced by IMPT with respect to 2F.

CONCLUSIONS

Proton beams improved all dosimetric parameters for NBL and WT patients compared to photon techniques. This improvement was limited for IMXT mainly to parameters related to the steep high-dose gradient. Further research is needed to minimize uncertainties for secondary cancer estimations.

Obstetric history and birth characteristics and Wilms tumor: a report from the Children's Oncology Group

Previous epidemiologic studies have suggested that various pregnancy and birth characteristics may be associated with Wilms tumor, a childhood kidney tumor. We evaluated obstetric events and birth characteristics in relation to Wilms tumor using data from a large North American case-control study. Mothers of 521 children with Wilms tumor and 517 controls, frequency matched on child's age and geographic region, provided information about their labor and delivery history and their children's birth characteristics through a detailed computer-assisted telephone interviews. Most obstetric factors were not associated with Wilms tumor, but modest associations were observed for labor induction (OR: 1.4, 95% Confidence Interval (CI): 1.1, 1.8), prenatal vaginal infection (OR: 1.8, 95% CI: 1.2, 2.8), and upper respiratory infection (OR: 1.5, 95% CI: 1.0, 2.4). Low (<2500 g) and high (>4500 g) birth weight and preterm delivery (<37 weeks completed gestation) were associated with an elevated risk of Wilms tumor, as was neonatal respiratory problems. The association for high birth weight was present only among children with perilobar nephrogenic rests (OR: 2.1, 95% CI: 1.2, 3.9), possibly distinguishing a specific association among a biologically distinct subgroup of Wilms tumor cases. The results of this large study did not support many of the earlier findings of smaller studies. However, additional investigations of the effects of certain obstetric and birth characteristics among more refined tumor subgroups may further our understanding of these factors in relation to Wilms tumor.

[Pediatric renal cell carcinoma. A rare differential diagnosis of Wilms' tumor]

Renal cell carcinoma (RCC) is a very rare pediatric disease and should be treated as an entity of its own because of differences in symptoms, therapy, and prognosis from the adult form of the disease. Our objective is to discuss the difficulties in clinical diagnosis, prognosis, and therapy of this very rare disease in children and to provide a review of the current literature.