International variations in the incidence of childhood renal tumours

Inter-Ethnic Variations in the Clinical, Pathological, and Molecular Characteristics of Wilms Tumor

Wilms tumor is the commonest primary renal malignancy in children and demonstrates substantial inter-ethnic variation in clinical, pathological, and molecular characteristics. Wilms tumor occurs at a lower incidence and at a younger age in Asians compared to Caucasians and Africans. Asians also present at an earlier stage of disease, with a higher incidence of favorable histology tumors and a lower incidence of perilobar nephrogenic rests compared to Caucasians, while African children present with more advanced disease. Studies have implicated population differences in the incidence of WT1 mutations, loss of imprinting of the IGF2 locus, and loss of heterozygosity of 1p/16q, or 1q gain as possible bases for epidemiological differences in the disease profile of Wilms tumors in various ethnic groups. Yet, evidence to support these associations is confounded by differences in treatment protocols and inequalities in the availability of treatment resources and remains limited by the quality of population-based data, especially in resource-limited settings.

LMO family gene polymorphisms and Wilms tumor susceptibility in Chinese children: a five-center case-control study

BACKGROUND

Wilms tumor is the most prevalent embryonal kidney malignancy in children worldwide. Previous genome-wide association study (GWAS) identified that LIM domain only 1 (LMO1) gene polymorphisms affected the susceptibility to develop certain tumor types. Apart from LMO1, the LMO gene family members also include LMO2-4, each of which has oncogenic potential.

METHODS

We conducted this five-center case‒control study to assess the correlations between single nucleotide polymorphisms in LMO family genes and Wilms tumor susceptibility. Odds ratios and 95% confidence intervals were calculated to evaluate the strength of the association.

RESULTS

We found LMO1 rs2168101 G > T and rs11603024 C > T as well as LMO2 rs7933499 G > A were significantly associated with Wilms tumor risk. Stratified analysis demonstrated a protective role of rs2168101 GT/TT genotypes against Wilms tumor in the subgroups of age ≤ 18 months, males and clinical stages I/II compared to the rs2168101 GG genotype. Nevertheless, carriers with the rs11603024 TT genotype were more likely to have an increased risk of Wilms tumor than those with rs11603024 CC/CT genotypes in age > 18 months. And the rs11603024 was identified as a protective polymorphism for reducing the risk of Wilms tumor in the sex- and gender- subgroup. Likewise, carriers with the rs7933499 GA/AA genotypes were at significantly elevated risk of Wilms tumor in age ≤ 18 months and clinical stages I/II.

CONCLUSION

Overall, our study identified the importance of LMO family gene polymorphisms on Wilms tumor susceptibility in Chinese children. Further investigations are needed to validate our conclusions.

Race and Ethnic Group Enrollment and Outcomes for Wilms Tumor: Analysis of the Current Era Children's Oncology Group Study, AREN03B2

BACKGROUND

To review race and ethnic group enrollment and outcomes for Wilms tumor (WT) across all 4 risk-assigned therapeutic trials from the current era Children's Oncology Group Renal Tumor Biology and Risk Stratification Protocol, AREN03B2.

STUDY DESIGN

For patients with WT enrolled in AREN03B2 (2006 to 2019), disease and biologic features, therapeutic study-specific enrollment, and event-free (EFS) and overall (OS) 4-year survival were compared between institutionally reported race and ethnic groups.

RESULTS

Among 5,146 patients with WT, no statistically significant differences were detected between race and ethnic groups regarding subsequent risk-assigned therapeutic study enrollment, disease stage, histology, biologic factors, or overall EFS or OS, except the following variables: Black children were older and had larger tumors at enrollment, whereas Hispanic children had lower rates of diffuse anaplasia WT and loss of heterozygosity at 1p. The only significant difference in EFS or OS between race and ethnic groups was observed among the few children treated for diffuse anaplasia WT with regimen UH-1 and -2 on high-risk protocol, AREN0321. On this therapeutic arm only, Black children showed worse EFS (hazard ratio = 3.18) and OS (hazard ratio = 3.42). However, this finding was not replicated for patients treated with regimen UH-1 and -2 under AREN03B2 but not on AREN0321.

CONCLUSIONS

Race and ethnic group enrollment appeared constant across AREN03B2 risk-assigned therapeutic trials. EFS and OS on these therapeutic trials when analyzed together were comparable regarding race and ethnicity. Black children may have experienced worse stage-specific survival when treated with regimen UH-1 and -2 on AREN0321, but this survival gap was not confirmed when analyzing additional high-risk AREN03B2 patients.

Prognostic role of primary tumor size in Wilms tumor

Wilms tumor (WT) is the most common childhood malignant kidney tumor. The aim of the present study was to determine the impact of primary tumor size on the survival of patients with WT. The data of 1,523 patients diagnosed with WT between 2000 and 2017 were retrieved from the Surveillance, Epidemiology, and End Results database. Receiver operating characteristic curves were plotted to determine the optimal cut-off value of primary tumor size. Overall survival (OS) and cancer-specific survival (CSS) were analyzed using the Kaplan-Meier method and the Cox proportional hazards regression model. The optimal cut-off value for primary tumor size was found to be 11.15 cm. No significant difference in the distribution of tumor size was detected between male and female patients. However, lymph node metastasis and distant metastasis were significantly more frequent in patients whose tumor was ≥11.15 cm in size compared with those with smaller tumors. In addition, patients with larger tumors exhibited significantly worse OS and CSS rates compared with those with smaller tumors. Furthermore, primary tumor size was identified as an independent prognostic factor for OS and CSS in the multivariate analyses. In summary, the present study indicates that primary tumor size is an independent prognostic factor for patients with WT, and tumors ≥11.15 cm are associated with worse OS and CSS.

WDR4 gene polymorphisms and Wilms tumor susceptibility in Chinese children: A five-center case-control study

Wilms tumor is the most common embryonal renal malignancy in children. WDR4 is an indispensable noncatalytic subunit of the RNA N7-methylguanosine (m7G) methyltransferase complex and plays an essential role in tumorigenesis. However, the relationship between polymorphisms in the WDR4 gene and susceptibility to Wilms tumor remains to be fully investigated. We performed a large case-control study involving 414 patients and 1199 cancer-free controls to investigate whether single nucleotide polymorphisms (SNPs) in the WDR4 gene are associated with Wilms tumor susceptibility. WDR4 gene polymorphisms (rs2156315 C > T, rs2156316 C > G, rs6586250 C > T, rs15736 G > A, and rs2248490 C > G) were genotyped using the TaqMan assay. In addition, unconditioned logistic regression analysis was performed, odds ratios (ORs) and 95% confidence intervals (CIs) were used to assess the association between WDR4 gene SNPs and Wilms tumor susceptibility as well as the strength of the associations. We found that only the rs6586250 C>T polymorphism was significantly associated with an increased risk of Wilms tumor (adjusted OR=2.99, 95% CI = 1.28-6.97, P = 0.011 for the rs6586250 TT genotype; adjusted OR=3.08, 95% CI = 1.33-7.17, P = 0.009 for the rs6586250 CC/CT genotype). Furthermore, the stratification analysis revealed that patients with the rs6586250 TT genotype and carriers with 1-5 risk genotypes exhibited statistically significant associations with increased Wilms tumor risk in specific subgroups. However, the rs2156315 CT/TT genotype was identified as having a protective effect against Wilms tumor in the age >18 months subgroup compared with the rs2156315 CC genotype. In brief, our study demonstrated that the rs6586250 C > T polymorphism of the WDR4 gene was significantly associated with Wilms tumor. This finding may contribute to the understanding of the genetic mechanism of Wilms tumor.

Pediatric renal tumor epidemiology: Global perspectives, progress, and challenges

Pediatric renal tumors account for 3%-11% of childhood cancers, the most common of which is Wilms tumor or nephroblastoma. Epidemiology plays a key role in cancer prevention and control by describing the distribution of cancer and discovering risk factors for cancer. Large pediatric research consortium trials have led to a clearer understanding of pediatric renal tumors, identification of risk factors, and development of more risk-adapted therapies. These therapies have improved event-free and overall survival for children. However, several challenges remain and not all children have benefited from the improved outcomes. In this article, we review the global epidemiology of pediatric renal tumors, including key consortium and global studies. We identify current knowledge gaps and challenges facing both high and low middle-incomes countries.

Pediatric renal tumor epidemiology: Global perspectives, progress, and challenges

Pediatric renal tumors account for 3%-11% of childhood cancers, the most common of which is Wilms tumor or nephroblastoma. Epidemiology plays a key role in cancer prevention and control by describing the distribution of cancer and discovering risk factors for cancer. Large pediatric research consortium trials have led to a clearer understanding of pediatric renal tumors, identification of risk factors, and development of more risk-adapted therapies. These therapies have improved event-free and overall survival for children. However, several challenges remain and not all children have benefited from the improved outcomes. In this article, we review the global epidemiology of pediatric renal tumors, including key consortium and global studies. We identify current knowledge gaps and challenges facing both high and low middle-incomes countries.

Macrophages and monocytes mediated activation of oxidative phosphorylation implicated the prognosis and clinical therapeutic strategy of Wilms tumour

Wilms tumour is the fourth leading cause of paediatric malignancy, but the detailed relationship between the tumour microenvironment and prognosis remains largely unclear. In this research, gene expression profile and clinical information from TARGET and the First Affiliated Hospital of Anhui Medical University were collected. After comparing the prognostic value of the associated immune cells, we established a nomogram to predict the prognosis of Wilms tumour based on monocyte infiltration, macrophage infiltration, stage, and sex. Further results showed that the most significant relationship between matrix metallopeptidase 9 and prognosis or macrophage infiltration. Meanwhile, by gene set enrichment or variation analyses and immunohistochemistry staining, we demonstrated that the most highly enriched hub genes were closely related to the activated oxidative phosphorylation pathway. Finally, through tumour immune dysfunction and an exclusion algorithm, the satisfactory discriminative performance of our nomogram was revealed for predicting the response to clinical therapy. Anti-PD1 therapy is more suitable for Wilms tumour patients with high nomogram points, and chemotherapies are more effective for patients with low nomogram score.

Long-term kidney function in children with Wilms tumour and constitutional WT1 pathogenic variant

BACKGROUND

Wilms tumour (WT) survivors, especially patients with associated syndromes or genitourinary anomalies due to constitutional WT1 pathogenic variant, have increased risk of kidney failure. We describe the long-term kidney function in children with WT and WT1 pathogenic variant to inform the surgical strategy and oncological management of such complex children.

METHODS

Retrospective analysis of patients with WT and constitutional WT1 pathogenic variant treated at a single centre between 1993 and 2016, reviewing genotype, phenotype, tumour histology, laterality, treatment, patient survival, and kidney outcome.

RESULTS

We identified 25 patients (60% male, median age at diagnosis 14 months, range 4-74 months) with WT1 deletion (4), missense (2), nonsense (8), frameshift (7), or splice site (4) pathogenic variant. Thirteen (52%) had bilateral disease, 3 (12%) had WT-aniridia, 1 had incomplete Denys-Drash syndrome, 11 (44%) had genitourinary malformation, and 10 (40%) had no phenotypic anomalies. Patient survival was 100% and 3 patients were in remission after relapse at median follow-up of 9 years. Seven patients (28%) commenced chronic dialysis of which 3 were after bilateral nephrectomies. The overall kidney survival for this cohort as mean time to start of dialysis was 13.38 years (95% CI: 10.3-16.4), where 7 patients experienced kidney failure at a median of 5.6 years. All of these 7 patients were subsequently transplanted. In addition, 2 patients have stage III and stage IV chronic kidney disease and 12 patients have albuminuria and/or treatment with ACE inhibitors. Four patients (3 frameshift; 1 WT1 deletion) had normal blood pressure and kidney function without proteinuria at follow-up from 1.5 to 12 years.

CONCLUSIONS

Despite the known high risk of kidney disease in patients with WT and constitutional WT1 pathogenic variant, nearly two-thirds of patients had sustained native kidney function, suggesting that nephron-sparing surgery (NSS) should be attempted when possible without compromising oncological risk. Larger international studies are needed for accurate assessment of WT1genotype-kidney function phenotype correlation.

The role of m6A modification in pediatric cancer

With the development of RNA modification research, the importance of N6-methyladenosine (m6A) in tumors cannot be ignored. m6A promotes the self-renewal of tumor stem cells and the proliferation of tumor cells. It affects post-transcriptional gene expression through epigenetic mechanisms, combining various factors to determine proteins' fate and altering the biological function. This modification process runs through the entire tumors, and genes affected by m6A modification may be the critical targets for cancers breakthroughs. Though generally less dangerous than adult cancer, pediatric cancer accounts for a significant proportion of child deaths. What is more alarming is that the occurrences of adult tumors are highly associated with the poor prognoses of pediatric tumors. Therefore, it is necessary to pay attention to the importance of pediatric cancer and discover new therapeutic targets, which will help improve the therapeutic effect and prognoses of the diseases. We collected and investigated m6A modification in pediatric cancers based on mRNA and non-coding RNA, finding that m6A factors were involved in glioma, hepatoblastoma, nephroblastoma, neuroblastoma, osteosarcoma, medulloblastoma, retinoblastoma, and acute lymphoblastic leukemia. Consequently, we summarized the relationships between the m6A factors and these pediatric cancers.

A Metabonomic View on Wilms Tumor by High-Resolution Magic-Angle Spinning Nuclear Magnetic Resonance Spectroscopy

Pediatric cancer NMR-metabonomics might be a powerful tool to discover modified biochemical pathways in tumor development, improve cancer diagnosis, and, consequently, treatment. Wilms tumor (WT) is the most common kidney tumor in young children whose genetic and epigenetic abnormalities lead to cell metabolism alterations, but, so far, investigation of metabolic pathways in WT is scarce. We aimed to explore the high-resolution magic-angle spinning nuclear magnetic resonance (HR-MAS NMR) metabonomics of WT and normal kidney (NK) samples. For this study, 14 WT and 7 NK tissue samples were obtained from the same patients and analyzed. One-dimensional and two-dimensional HR-MAS NMR spectra were processed, and the one-dimensional NMR data were analyzed using chemometrics. Chemometrics enabled us to elucidate the most significant differences between the tumor and normal tissues and to discover intrinsic metabolite alterations in WT. The metabolic differences in WT tissues were revealed by a validated PLS-DA applied on HR-MAS T₂-edited ¹H-NMR and were assigned to 16 metabolites, such as lipids, glucose, and branched-chain amino acids (BCAAs), among others. The WT compared to NK samples showed 13 metabolites with increased concentrations and 3 metabolites with decreased concentrations. The relative BCAA concentrations were decreased in the WT while lipids, lactate, and glutamine/glutamate showed increased levels. Sixteen tissue metabolites distinguish the analyzed WT samples and point to altered glycolysis, glutaminolysis, TCA cycle, and lipid and BCAA metabolism in WT. Significant variation in the concentrations of metabolites, such as glutamine/glutamate, lipids, lactate, and BCAAs, was observed in WT and opened up a perspective for their further study and clinical validation.

Exposure to pesticides and pediatric Wilms’ tumor. A meta-analysis on pre-conception and pregnancy parental exposure with an IARC/WHO commentary

Background

There are hereditary types of nephroblastoma or Wilms’ tumor associated with exposure of the germ cells of either parent to harmful environmental factors. Some studies have examined the exposure of compounds used pesticides and herbicides as a risk factor for Wilms’ tumor.

Methods

A systematic review and meta-analysis were carried out on case-control studies to establish the potential link between exposure to these organic molecules and Wilms’ tumor occurrence in children rigorously. We examined the monographs on some organo-phosphate insecticides and herbicides issued by the International Association for the Research on Cancer (IARC) under the auspices of the World Health Organization (WHO). PUBMED, SCOPUS, and Google Scholar studies (1960–2021) were identified and systematically reviewed following Preferred Reporting Items for Systematic reviews and Meta-Analyses (PRISMA) guidelines. Subgroup analyses were conducted after stratification for occupational versus residential exposure and before birth (prenatal) vs. after birth (postnatal) exposure. In addition, we revised the monographs on chemical compounds issued recently by the IARC/WHO.

Results

Our findings seem to consolidate that parental pesticide exposure during the preconception or pregnancy period is correlated with an increased occurrence risk for Wilms’ tumor. We confirm the validity of the WHO essays on certain organophosphate herbicides and insecticides, which support these compounds, may be highly relevant in future cancer prevention policies.

Conclusion

Parental exposure to pesticides, particularly in household settings, is poorly emphasized in our society. There is a strong association between these organophosphate compounds and pediatric cancer. Public health agencies may need to take stronger action than in the past.

Wilms tumour

Wilms tumour (WT) is a childhood embryonal tumour that is paradigmatic of the intersection between disrupted organogenesis and tumorigenesis. Many WT genes play a critical (non-redundant) role in early nephrogenesis. Improving patient outcomes requires advances in understanding and targeting of the multiple genes and cellular control pathways now identified as active in WT development. Decades of clinical and basic research have helped to gradually optimize clinical care. Curative therapy is achievable in 90% of affected children, even those with disseminated disease, yet survival disparities within and between countries exist and deserve commitment to change. Updated epidemiological studies have also provided novel insights into global incidence variations. Introduction of biology-driven approaches to risk stratification and new drug development has been slower in WT than in other childhood tumours. Current prognostic classification for children with WT is grounded in clinical and pathological findings and in dedicated protocols on molecular alterations. Treatment includes conventional cytotoxic chemotherapy and surgery, and radiation therapy in some cases. Advanced imaging to capture tumour composition, optimizing irradiation techniques to reduce target volumes, and evaluation of newer surgical procedures are key areas for future research.

Comparative analysis of the clinical characteristics and outcomes of patients with Wilms tumor in the United Kingdom and Japan

BACKGROUND

Wilms tumor (WT) demonstrates epidemiological differences by world region and ethnicity. To enhance understanding of these differences, we retrospectively analyzed clinical trial data sets from the UK and Japan over a 20-year period.

PROCEDURE

We used data from three consecutive clinical trials in the UK and a single study in Japan that enrolled patients diagnosed during 1996-2015, to compare clinical characteristics and outcomes between countries.

RESULTS

During 1996-2015, 1395 patients in the UK and 537 in Japan were included. Japanese patients have a significantly younger median age at diagnosis than those in the UK (28 months vs 39 months). The proportion of patients with stage IV, large tumors, and anaplastic histology appears to be higher in the UK than in Japan (18% vs 11%, 62% vs 49%, 8% vs 3%, respectively). During 2005-2015, 77 hospitals treated WT in Japan compared with only 20 hospitals in the UK. Five-year overall survival of patients with WT was over 90% in both countries, but five-year event-free survival of patients with stage IV was significantly lower in Japan than in the UK (50.0% vs 76.2%, P = 0.001).

CONCLUSIONS

Differences in age of onset, tumor size at diagnosis, and histology may reflect differences in the genetic background of patients with WT between countries, but population-based phenotype-genotype data are lacking. The difference in survival probability for stage IV patients may be due to different diagnostic criteria or different treatment strategies. Prospective, international clinical studies including genomic analyses are needed to confirm these findings and improve clinical practice.

Trends in childhood cancer incidence in sub-Saharan Africa: Results from 25 years of cancer registration in Harare (Zimbabwe) and Kyadondo (Uganda)

We examined trends in childhood cancer incidence in sub-Saharan Africa using data from two population-based cancer registries in Harare (Zimbabwe) and Kyadondo (Uganda) with cases classified according to the International Classification of Childhood Cancer and explored reasons for observed variations and changes. Over the whole 25-year period (1991-2015) studied, there were only small, and nonsignificant overall trends in incidence. Nevertheless, within the period, peaks in incidence occurred from 1996 to 2001 in Harare (Zimbabwe) and from 2003 to 2006 in Kyadondo (Uganda). Kaposi sarcoma and non-Hodgkin lymphoma accounted for the majority of the cases during these periods. These fluctuations in incidence rates in both registries can be linked to similar trends in the prevalence of HIV, and the availability of antiretroviral therapy. In addition, we noted that, in Harare, incidence rates dropped from 2003 to 2004 and 2007 to 2008, correlating with declines in national gross domestic product. The results indicate that the registration of childhood cancer cases in resource-poor settings is linked to the availability of diagnostic services mediated by economic developments. The findings highlight the need for specialised diagnostic and treatment programmes for childhood cancer patients as well as positive effects of HIV programmes on certain childhood cancers.

New mutation in WT1 gene in a boy with an incomplete form of Denys-Drash syndrome: A CARE-compliant case report

RATIONALE

Pediatric patients with WTl-associated syndromes (including Wilms' tumor-aniridia syndrome and Denys-Drash syndrome), Perlman syndrome, mosaic aneuploidy, and Fanconi anemia with a biallelic breast cancer type 2 susceptibility protein mutation have the highest risk of developing Wilms' tumor.

PATIENT CONCERNS AND DIAGNOSIS

We describe a patient with bilateral metachronous Wilms' tumor, ambiguous genitalia characterized by 46, XY disorder of sexual development (DSD) with scrotal hypospadias and bilateral abdominal cryptorchidism, but without nephropathy. At the age of 7 months, the child underwent left nephrectomy with left orchiopexy. At follow-up after 8 months, a second tumor with a diameter of 10 mm was detected in abdominal CT scans at the lower pole of the right kidney.

INTERVENTION

Intra-operative macroscopic inspection of the right kidney revealed a tight attachment of the right proximal ureter to the tumor. Thus, retroperitoneoscopic resection of the lower pole of the right kidney had to be changed to an open surgical procedure with partial resection of the proximal ureter and high uretero-ureterostomy. We subsequently performed orchiopexy and two-stage correction of hypospadias using a free skin graft.

OUTCOMES

At the last follow-up at the age of 8 years, no pathology requiring treatment was noted. A pair-end-reading (2 × 125) DNA analysis with an average coverage of at least 70 to 100 × revealed a previously unknown heterozygous mutation in exon 7 of the Wilms' tumor suppressor gene 1 (WT1) gene (chr11:32417947G>A), leading to the appearance of a site of premature translation termination in codon 369 (p.Arg369Ter, NM_024426.4). This mutation had not been registered previously in the control samples "1000 genomes," Exome Sequencing Project 6500, and the Exome Aggregation Consortium. Thus, to the best of our knowledge this represents a newly identified mutation causing incomplete Denys-Drash syndrome.

Non-coding RNAs in Wilms' tumor: biological function, mechanism, and clinical implications

Non-coding RNAs are involved with maintenance and regulation of physiological mechanisms and are involved in pathological processes, such as cancer. Among the small ncRNAs, miRNAs are the most explored in tumorigenesis, metastasis development, and resistance to chemotherapy. These small molecules of ~ 22 nucleotides are modulated during early renal development, involved in the regulation of gene expression and Wilms' tumor progression. Wilms' tumors are embryonic tumors with few mutations and complex epigenetic dysregulation. In recent years, the small ncRNAs have been explored as potentially related both in physiological development and in the tumorigenesis of several types of cancer. Besides, genes regulated by miRNAs are related to biological pathways as PI3K, Wnt, TGF-β, and Hippo signaling pathways, among others, which may be involved with the underlying mechanisms of resistance to chemotherapy, and in this way, it has emerged as potential targets for cancer therapies, including for Wilms' tumors.

DICER1 Syndrome and Cancer Predisposition: From a Rare Pediatric Tumor to Lifetime Risk

DICER1 syndrome is a rare genetic condition predisposing to hereditary cancer and caused by variants in the DICER1 gene. The risk to present a neoplasm before the age of 10 years is 5.3 and 31.5% before the age of 60. DICER1 variants have been associated with a syndrome involving familial pleuropulmonary blastoma (PPB), a rare malignant tumor of the lung, which occurs primarily in children under the age of 6 years and represents the most common life-threatening manifestation of DICER1 syndrome. Type I, II, III, and Ir (type I regressed) PPB are reported with a 5-year overall survival ranging from 53 to 100% (for type Ir). DICER1 gene should be screened in all patients with PPB and considered in other tumors mainly in thyroid neoplasms (multinodular goiter, thyroid cancer, adenomas), ovarian tumors (Sertoli-Leydig cell tumor, sarcoma, and gynandroblastoma), and cystic nephroma. A prompt identification of this syndrome is necessary to plan a correct follow-up and screening during lifetime.

Incidence of childhood renal tumours: An international population-based study

Malignant renal tumours represent 5% of childhood cancers and include types with likely different aetiology: Wilms tumour (WT), rhabdoid renal tumour, kidney sarcomas and renal carcinomas. WT is the most common renal tumour in children, previously shown to vary internationally and with ethnicity. Using the comprehensive database of the International Incidence of Childhood Cancer study (IICC), we analysed global variations and time trends in incidence of renal tumour types in children (age 0-14 years) and adolescents (age 15-19 years). The results were presented by 14 world regions, and five ethnic groups in the US. We included 15 320 renal tumours in children and 800 in adolescents reported to the 163 contributing registries during 2001-2010. In children, age-standardised incidence rate (ASR) of renal tumours was 8.3 per million (95% confidence interval, CI = 8.1, 8.4); it was the highest in North America and Europe (9-10 per million) and the lowest in most Asian regions (4-5 per million). In the US, Blacks had the highest ASR (10.9 per million, 95% CI = 10.2, 11.6) and Asian and Pacific Islanders the lowest (4.4 per million, 95% CI = 3.6, 5.1). In adolescents, age-specific incidence rate of renal tumours was 1.4 per million (95% CI = 1.3, 1.5). WT accounted for over 90% of all renal tumours in each age from 1 to 7 years and the proportion of renal carcinomas increased gradually with age. From 1996 to 2010, incidence remained mostly stable for WT (average annual percent change, AAPC = 0.1) and increased for renal carcinomas in children (AAPC = 3.7) and adolescents (AAPC = 3.2). Our findings warrant further monitoring.

Factores asociados a la sobrevida en pacientes con tumor de Wilms

Introducción. El tumor de Wilms es el segundo tumor abdominal más frecuente en la edad pediátrica y responde por más del 90 % de los tumores renales en pediatría. A pesar de que la sobrevida descrita es mayor del 90 %, en nuestro medio encontramos que solo alcanza al 70 %, por lo que deseamos evaluar cuáles son los factores asociados con dichos resultados desfavorables, con el fin de implementar medidas para mejorar la sobrevida de nuestros pacientes. Métodos. Se realizó un estudio observacional, transversal, en dos centros de alto nivel de atención, que incluyó una muestra de 84 pacientes menores de 15 años, con diagnóstico de tumor de Wilms. Resultados. Los factores que se asociaron significativamente con un aumento en la probabilidad de morir fueron: no completar el protocolo de quimioterapia, (OR 34; IC95% 3,7-312; p 0,000) y presentar recidiva tumoral (OR 35,7; IC95% 6,9-184; p 0,000). Otros factores que aumentaron esta probabilidad sin alcanzar a ser significativos, pero mostrando una evidente tendencia fueron: presentación bilateral (OR 4,1; IC95% 0,6-5,5; p 0,147), complicaciones quirúrgicas (OR 3,2; IC95% 0,7-14,6; p 0,136), compromiso de ganglios linfáticos en tomografía (OR 2,4; IC95% 0,7-8,4; p 0,139) y las metástasis a distancia (OR 2,5; IC95% 0,7-9; p 0,143). Discusión. La sobrevida de nuestros niños con tumor de Wilms es menor que la reportada en la literatura mundial, siendo la falla en terminar la quimioterapia, la recidiva y la necesidad de cirugía bilateral, los factores asociados con este desenlace.  

Race, ethnicity, and socioeconomic differences in incidence of pediatric embryonal tumors in the United States

BACKGROUND

The etiology of childhood cancers and its social patterning remains largely unknown. Accounting for socioeconomic status (SES) when exploring the association between race/ethnicity and cancer incidence is necessary to better understand such etiology. We aimed to investigate differences in the incidence of embryonal tumors (ETs) by SES and race/ethnicity in the United States using population-based registries of the Surveillance, Epidemiology, and End Results (SEER) Program.

PROCEDURE

Children with ETs aged 0-19 years diagnosed between 2000 and 2015 were ascertained from the census tract-level SEER database. SES was measured using a tract-level composite index. Incidence rate ratios (IRRs) with 95% confidence intervals (CIs) by SES quintile and race/ethnicity were estimated using multivariable Poisson regression models.

RESULTS

The majority of tumors had lower incidence among nonwhite children compared with non-Hispanic (NH) white children, after controlling for SES. NH blacks had a higher incidence of Wilms tumor than NH whites (IRR: 1.26; 95% CI, 1.13-1.39). There was an increasing linear trend (P = 0.0001) across increasing SES quintile for embryonal rhabdomyosarcoma after controlling for race/ethnicity. Effect modification by race/ethnicity of the relationship between SES and tumor incidence was observed for several groups. Hispanics had a significant, linear trend (P = 0.0005) in the incidence of Wilms tumor, while Asian/Pacific Islanders experienced a significant inverse trend (P = 0.0002).

CONCLUSIONS

Results from this study suggest differences in the incidence of several ETs by race/ethnicity and that these differences may be modified by SES. Investigation of potential risk factors that are socially patterned is warranted.

Health disparities among tennessee pediatric renal tumor patients

BACKGROUND/PURPOSE

Wilms tumor (WT) poses a cancer health disparity to black children globally, which has not been evaluated thoroughly for other pediatric renal cancers. We aimed to characterize health disparities among Tennessee children treated for any renal cancer.

METHODS

The Tennessee Cancer Registry (TCR) was queried for patients ≤18 years having any renal cancer (n = 160). To clarify treatment and outcomes, we performed a retrospective cohort study of pediatric renal cancer patients in our institutional cancer registry (ICR; n = 121). Diagnoses in both registries included WT, Sarcoma/Other, and Renal Cell Carcinoma. Wilcoxon/Pearson, Kaplan-Meier, and logistic regression were completed.

RESULTS

In both registries, WT comprised the most common renal cancer and youngest median age. Sarcoma was intermediate in frequency and age, and RCC was least common, having the oldest age (p < 0.001). In the TCR, black patients comprised 26% of all patients, presented more commonly with distant disease than white patients (37% v. 16%; p = 0.021), and showed worse overall survival (73% v. 89%; p = 0.018), while the ICR showed similar survival between race groups (92% v. 93%, p = 0.868). Sarcoma and metastases were independent predictors of death in both registries (p ≤ 0.002).

CONCLUSIONS

Black children in Tennessee presented with more advanced disease and experienced worse survival when combining all renal cancer types, particularly RCC and Sarcoma. When treated at a comprehensive pediatric cancer center, these survival disparities appear diminished.

TYPE OF STUDY

Prognostic study.

LEVEL OF EVIDENCE

Level II (retrospective cohort).

Absence of the TRIP13 c.1060C>T Mutation in Wilms Tumor Patients From Pakistan

BACKGROUND AND AIM

Wilms tumor (WT) is the most common childhood malignant renal tumor. Germline mutations in several WT predisposition genes have been identified. However, the fundamental cause of most WT patients remains unexplained. Recently, a founder mutation, c.1060C>T (p. Arg254X) in a mitotic spindle checkpoint gene, TRIP13, was reported in 5 unrelated children with WT from the United Kingdom, of Pakistani descent from Azad Kashmir region. This observation suggests other children with WT in Pakistan may also harbor this mutation. We conducted the first study to assess the contribution of TRIP13 c.1060C>T mutation to WT in Pakistan.

MATERIALS AND METHODS

Constitutional genomic DNA from 68 Pakistani individuals including unrelated WT cases (n=26) and one (n=10) or both (n=32) of their parent(s) were screened for the TRIP13 c.1060C>T mutation using DNA sequence analysis. We also included positive controls in the analyses.

RESULTS

The median age of WT diagnosis was 3.0 years (range, 0.75 to 10). The TRIP13 c.1060C>T mutation was not found in any WT patient (n=26) or their parents (n=42). Twenty-four patients (92.4%) presented with unilateral tumor and 2 patients (7.7%) were diagnosed with synchronous bilateral WT. Thirteen patients (50%) reported parental consanguinity. Thirteen patients (50.0%) belonged to the Punjabi ethnicity and 1 patient (3.8%) had a Kashmiri background. Four patients (16.7%) reported a family history of WT or other malignancies. The predominant histologic subtype was stromal (46.2%). The majority of patients presented with >5 cm of tumor size (81%). None of the patients had a personal or family history of congenital anomalies, or associated genetic syndromes.

CONCLUSIONS

Our findings suggest that TRIP13 c.1060C>T mutation may be infrequent in Pakistani WT cases. Further evaluation of this mutation in a large number of WT patients of Kashmiri heritage and various ethnic backgrounds from Pakistan is warranted.

Intra-tumor genetic heterogeneity in Wilms tumor samples

Childhood renal tumors account for ~7% of all childhood cancers, and most cases are embryonic Wilms' tumors (WT). Children with WT are usually treated by either COG or SIOP. The later treats the children using preoperative chemotherapy, but both have around 90% of overall survival in five years. WT is a genetically heterogeneous group with a low prevalence of known somatic alterations. Only around 30% of the cases present mutation in known genes, and there is a relatively high degree of intra-tumor genetic heterogeneity (ITGH). Besides potentially having an impact on the clinical outcome of patients, ITGH may interfere with the search for molecular markers that are prospectively being tested by COG and SIOP. In this review, we present the proposal of the current UMBRELLA SIOP Study 2017/Brazilian Renal Tumor Group that requires the multi-sampling collection of each tumor to better evaluate possible molecular markers, as well as to understand WT biology.

MicroRNA-539 inhibits the progression of Wilms' Tumor through downregulation of JAG1 and Notch1/3

BACKGROUND

Previous studies demonstrated that miR-539 play an important role in the carcinogenesis of some cancers. The aim of the present study was to determine the role of miR-539 in the pathogenesis of Wilms' Tumor (WT).

METHODS

The expression level of miR-539 was measured by qRT-PCR in 42 WT tissues and SK-NEP-1 cell line. Protein expression of genes (E-cadherin, N-cadherin, Vimentin, Notch 1, Notch 3 and JAG1) was assessed by Western blot. The function of miR-539 was investigated in SK-NEP-1 cells by MTT and Transwell assays. The relationship between miR-539 and JAG1 was verified by a dual luciferase assay in SK-NEP-1 cells.

RESULTS

The expression level of miR-539 was significantly decreased in WT tissues. Downregulation of miR-539 was closely related to NWTS-5 stage, lymph node metastasis and histological type of WT patients. Furthermore, low miR-539 expression was associated with a shorter overall survival rate in WT patients. In vitro, overexpression of miR-539 suppressed proliferation, migration and invasion of SK-NEP-1 cells. In addition, JAG1 was a direct target of miR-539. MiR-539 inhibited the development of WT by inhibiting JAG1-Notch1/3 expressing and blocking EMT.

CONCLUSION

MiR-539 inhibited the progression of WT through downregulation of JAG1 and Notch1/3.

Molecular and epidemiologic characterization of Wilms tumor from Baghdad, Iraq

BACKGROUND

Wilms tumor (WT) is the most common childhood kidney cancer worldwide, yet its incidence and clinical behavior vary according to race and access to adequate healthcare resources. To guide and streamline therapy in the war-torn and resource-constrained city of Baghdad, Iraq, we conducted a first-ever molecular analysis of 20 WT specimens to characterize the biological features of this lethal disease within this challenged population.

METHODS

Next-generation sequencing of ten target genes associated with WT development and treatment resistance (WT1, CTNNB1, WTX, IGF2, CITED1, SIX2, p53, N-MYC, CRABP2, and TOP2A) was completed. Immunohistochemistry was performed for 6 marker proteins of WT (WT1, CTNNB1, NCAM, CITED1, SIX2, and p53). Patient outcomes were compiled.

RESULTS

Mutations were detected in previously described WT "hot spots" (e.g., WT1 and CTNNB1) as well as novel loci that may be unique to the Iraqi population. Immunohistochemistry showed expression domains most typical of blastemal-predominant WT. Remarkably, despite the challenges facing families and care providers, only one child, with combined WT1 and CTNNB1 mutations, was confirmed dead from disease. Median clinical follow-up was 40.5 months (range 6-78 months).

CONCLUSIONS

These data suggest that WT biology within a population of Iraqi children manifests features both similar to and unique from disease variants in other regions of the world. These observations will help to risk stratify WT patients living in this difficult environment to more or less intensive therapies and to focus treatment on cell-specific targets.

Childhood cancer research in Oxford II: The Childhood Cancer Research Group

BACKGROUND

We summarise the work of the Childhood Cancer Research Group, particularly in relation to the UK National Registry of Childhood Tumours (NRCT).

METHODS

The Group was responsible for setting up and maintaining the NRCT. This registry was based on notifications from regional cancer registries, specialist children's tumour registries, paediatric oncologists and clinical trials organisers. For a large sample of cases, data on controls matched by date and place of birth were also collected.

RESULTS

Significant achievements of the Group include: studies of aetiology and of genetic epidemiology; proposals for, and participation in, international comparative studies of these diseases and on a classification system specifically for childhood cancer; the initial development of, and major contributions to, follow-up studies of the health of long-term survivors; the enhancement of cancer registration records by the addition of clinical data and of birth records. The Group made substantial contributions to the UK government's Committee on Medical Aspects of Radiation in the Environment.

CONCLUSION

An important part of the ethos of the Group was to work in collaboration with many other organisations and individuals, both nationally and internationally: many of the Group's achievements described here were the result of such collaborations.

High-dose chemotherapy and autologous hematopoietic stem-cell rescue for treatment of relapsed and refractory Wilms tumor: Re-evaluating outcomes

Wilms tumor (WT) treatment regimens are curative for more than 80% of patients, but those with relapsed or refractory disease continue to have poor outcomes. High-dose chemotherapy followed by autologous stem cell rescue is often utilized although outcomes remain variable. We report on HD-ASCR outcomes in 24 patients with relapsed or refractory Wilms tumor. Three-year disease free and overall survival are 46% and 60%, respectively, which is similar to those reported for conventional salvage therapies. These outcomes suggest that conventional salvage therapies should be employed for relapsed and refractory WT rather than HD-ASCR.

Outcome of renal tumors registered in Japan Wilms Tumor Study-2 (JWiTS-2): A report from the Japan Children's Cancer Group (JCCG)

BACKGROUND

Japan Wilms Tumor Study-2 (JWiTS-2) mandated central pathology review for all case registrations. The study aimed to compare the outcomes of patients with unilateral Wilms tumor enrolled on the JWiTS-1 and JWiTS-2 trials.

PROCEDURE

The JWiTS-2 trial (2006-2014), a prospective, single-arm study, required compulsory submission of histologic slides to central pathology, while in the JWiTS-1 trial, such submission was not compulsory. Relapse-free survival (RFS) and overall survival (OS) versus cases in the JWiTS-1 trial (1996-2005) were statistically evaluated.

RESULTS

Of 277 enrolled patients with primary renal tumors diagnosed by the central pathology review system, 225 patients with unilateral renal tumors were followed up over 9 years. The RFS and OS of Wilms tumor (n = 178) were 90.4% (P = 0.0003) and 96.8% (P = 0.054), respectively, as compared to 74.9% and 89.4% in JWiTS-1. RFS rates of stages I-III Wilms tumor in JWiTS-2 were more than 90%, although the outcome of stage IV Wilms tumor was significantly poorer (RFS: 66.2%) (P = 0.0094). RFS and OS of clear cell sarcoma of the kidney (CCSK; n = 31) were 82.4% (P = 0.30) and 91.3% (P = 0.42), respectively, as compared to 68.8% and 81.3% in JWiTS-1, and those of rhabdoid tumor of the kidney (RTK; n = 16) were 18.8% (P = 0.88) and 25.0% (P = 0.80), respectively, as compared to 23.5% and 23.5% in JWiTS-1.

CONCLUSIONS

RFS and OS for stages I-III Wilms tumor were improved in JWiTS-2 compared to JWiTS-1, whereas outcomes for stage IV Wilms tumor, CCSK, and RTK did not improve.

Childhood cancer incidence and survival in Japan and England: A population-based study (1993-2010)

The present study aimed to compare cancer incidence and trends in survival for children diagnosed in Japan and England, using population-based cancer registry data. The analysis was based on 5192 children with cancer (age 0-14 years) from 6 prefectural cancer registries in Japan and 21 295 children diagnosed in England during 1993-2010. Differences in incidence rates between the 2 countries were measured with Poisson regression models. Overall survival was estimated using the Kaplan-Meier method. Incidence rates for Hodgkin lymphoma, renal tumors and Ewing sarcomas in England were more than twice as high as those in Japan. Incidence of germ cell tumors, hepatic tumors, neuroblastoma and acute myeloid leukemia (AML) was higher in Japan than in England. Incidence of all cancers combined decreased in Japan throughout the period 1993 to 2010, which was mainly explained by a decrease in registration of neuroblastoma in infants. For many cancers, 5-year survival improved in both countries. The improvement in survival in chronic myeloid leukemia (CML) was particularly dramatic in both countries. However, 5-year survival remained less than 80% in 2005-2008 in both countries for AML, brain tumors, soft tissue sarcomas, malignant bone tumors and neuroblastoma (age 1-14 years). There were significant differences in incidence of several cancers between countries, suggesting variation in genetic susceptibility and possibly environmental factors. The decrease in incidence for all cancers combined in Japan was related to the cessation of the national screening program for neuroblastoma. The large improvement in survival in CML coincided with the introduction of effective therapy (imatinib).

Cancer of childhood in sub-Saharan Africa

Measurement of incidence rates of childhood cancer in Africa is difficult. The study 'Cancer of Childhood in sub Saharan Africa' brings together results from 16 population-based registries which, as members of the African Cancer Registry Network (AFCRN), have been evaluated as achieving adequate coverage of their target population. The cancers are classified according to the third revision of the International Classification of Childhood Cancer (ICCC-3) and recorded rates in Africa are compared with those in childhood populations in the UK, France, and the USA. It is clear that, in many centres, lack of adequate diagnostic and treatment facilities leads to under-diagnosis (and enumeration) of leukaemias and brain cancers. However, for several childhood cancers, incidence rates in Africa are higher than those in high-income countries. This applies to infection-related cancers such as Kaposi sarcoma, Burkitt lymphoma, Hodgkin lymphoma and hepatocellular carcinoma, and also to two common embryonal cancers - retinoblastoma and nephroblastoma. These (and other) observations are unlikely to be artefact, and are of considerable interest when considering possible aetiological factors, including ethnic differences in risk (and hence genetic/familial antecedents). The data reported are the most extensive so far available on the incidence of cancer in sub Saharan Africa, and clearly indicate the need for more resources to be devoted to cancer registration, especially in the childhood age range, as part of an overall programme to improve the availability of diagnosis and treatment of this group of cancers, many of which have-potentially-an excellent prognosis.

Association between TP53 gene Arg72Pro polymorphism and Wilms' tumor risk in a Chinese population

Wilms' tumor is one of the most prevalent pediatric malignancies, ranking fourth in childhood cancer worldwide. TP53 is a critical tumor suppressor gene, which encodes a 53 kDa protein, p53. The p53 functions to protect against cancer by regulating cell cycle and apoptosis and maintaining DNA integrity. TP53 gene is highly polymorphic. Several TP53 gene polymorphisms have been considered to be associated with cancer risk. Of them, a nonsynonymous polymorphism, Arg72Pro (rs1042522 C>G), has been most extensively studied for the association with cancer risk; however, few studies have investigated its effect on Wilms' tumor. Because of the central role of p53 in cell cycle control, the TP53 gene Arg72Pro polymorphism is also a good potential candidate predisposition locus for this pediatric cancer. We genotyped this polymorphism in 145 patients and 531 cancer-free controls recruited from Chinese children by Taqman methodology. Overall, our result suggested a lack of association between the TP53 gene Arg72Pro polymorphism and Wilms' tumor. In the stratified analysis, we found that carriers of CG/GG genotypes had a significantly increased Wilms' tumor risk in children not older than 18 months (adjusted odds ratio =2.04, 95% confidence interval =1.003-4.13, P=0.049) compared with CC genotype carriers. Our study indicated that the TP53 gene Arg72Pro polymorphism may have a weak, age-related effect on Wilms' tumor risk in Chinese children. These findings need further validations in other populations with larger sample size.

Association between Long Interspersed Nuclear Element-1 Methylation and Relative Telomere Length in Wilms Tumor

Background:

DNA hypomethylation of long interspersed nuclear elements-1 (LINEs-1) occurs during carcinogenesis, whereas information addressing LINE-1 methylation in Wilms tumor (WT) is limited. The main purpose of our study was to quantify LINE-1 methylation levels and evaluate their relationship with relative telomere length (TL) in WT.

Methods:

We investigated LINE-1 methylation and relative TL using bisulfite-polymerase chain reaction (PCR) pyrosequencing and quantitative PCR, respectively, in 20 WT tissues, 10 normal kidney tissues and a WT cell line. Significant changes were analyzed by t-tests.

Results:

LINE-1 methylation levels were significantly lower (P < 0.05) and relative TLs were significantly shorter (P < 0.05) in WT compared with normal kidney. There was a significant positive relationship between LINE-1 methylation and relative TL in WT (r = 0.671, P = 0.001). LINE-1 Methylation levels were significantly associated with global DNA methylation (r = 0.332, P < 0.01). In addition, relative TL was shortened and LINE-1 methylation was decreased in a WT cell line treated with the hypomethylating agent 5-aza-2′-deoxycytidine compared with untreated WT cell line.

Conclusion:

These results suggest that LINE-1 hypomethylation is common and may be linked to telomere shortening in WT.

Imaging of Solid Kidney Tumours in Children

Eighteen children aged 6 months to 12 years with 20 solid renal tumours; 13 Wilms' tumours (WT), 2 clear cell sarcomas of the kidney, 1 malignant rhabdoid tumour of the kidney and 2 cases of bilateral nephroblastomatosis with Wilms' tumour underwent evaluation with US, CT and MR imaging. Contrast-enhanced CT and non-enhanced MR were equally accurate in determining the size and origin of the tumour but were unreliable in separation of stages I, II and III. US could only accurately assess the size of the tumours. MR characteristics varied somewhat between WTs and non-WTs but contrast-enhanced MR imaging might be useful for separation of WTs from nephroblastomatosis.

Clinical features and long-term outcomes of bilateral Wilms tumor treated with Taiwan Pediatric Oncology Group protocols: A single center report

AIMS

Wilms tumor (WT) is rare in Asia. Treatment of bilateral WT is challenging, and the treatment outcome of bilateral WT is rarely reported in low incidence areas.

METHODS

We enrolled patients with bilateral WT registered in Chang Gung Memorial Hospital, Taoyuan, Taiwan, between January 1986 and June 2015. They were treated according to the Taiwan Pediatric Oncology Group (TPOG) protocols. The clinical features and long-term outcomes were analyzed.

RESULTS

Six patients with histologically-proved bilateral WT were identified for analysis. One additional patient who was diagnosed with unilateral WT-associated intralobar nephrogenic rest, in addition to two small lesions in the contralateral kidney, was also included. There were total of three male patients and four female patients. The median follow-up period was 19 years (range 8-29 years). Five patients underwent initial biopsy and preoperative chemotherapy followed by surgery, whereas two patients underwent initial surgery followed by adjuvant chemotherapy. Local recurrence was found in two patients. The 8-year event-free survival and overall survival rates were 71.4% and 100%, respectively. Two patients developed advanced stage of chronic kidney disease, but none had been diagnosed with secondary malignant neoplasm. Other health issues such as hypertension, scoliosis and unspecified autoimmune disease were also found.

CONCLUSIONS

The treatment outcome in this study is comparably superior to other western countries. However, survivors of bilateral WT still have many chronic health issues and thereby need individualized long-term medical care.

Genetic variation frequencies in Wilms' tumor: A meta-analysis and systematic review

Over the last few decades, numerous biomarkers in Wilms' tumor have been confirmed and shown variations in prevalence. Most of these studies were based on small sample sizes. We carried out a meta-analysis of the research published from 1992 to 2015 to obtain more precise and comprehensive outcomes for genetic tests. In the present study, 70 out of 5175 published reports were eligible for the meta-analysis, which was carried out using Stata 12.0 software. Pooled prevalence for gene mutations WT1, WTX, CTNNB1, TP53, MYCN, DROSHA, and DGCR8 was 0.141 (0.104, 0.178), 0.147 (0.110, 0.184), 0.140 (0.100, 0.190), 0.410 (0.214, 0.605), 0.071 (0.041, 0.100), 0.082 (0.048, 0.116), and 0.036 (0.026, 0.046), respectively. Pooled prevalence of loss of heterozygosity at 1p, 11p, 11q, 16q, and 22q was 0.109 (0.084, 0.133), 0.334 (0.295, 0.373), 0.199 (0.146, 0.252), 0.151 (0.129, 0.172), and 0.148 (0.108, 0.189), respectively. Pooled prevalence of 1q and chromosome 12 gain was 0.218 (0.161, 0.275) and 0.273 (0.195, 0.350), respectively. The limited prevalence of currently known genetic alterations in Wilms' tumors indicates that significant drivers of initiation and progression remain to be discovered. Subgroup analyses indicated that ethnicity may be one of the sources of heterogeneity. However, in meta-regression analyses, no study-level characteristics of indicators were found to be significant. In addition, the findings of our sensitivity analysis and possible publication bias remind us to interpret results with caution.

Genomic imbalances pinpoint potential oncogenes and tumor suppressors in Wilms tumors

BACKGROUND

Wilms tumor (WT) has a not completely elucidated pathogenesis. DNA copy number alterations (CNAs) are common in cancer, and often define key pathogenic events. The aim of this work was to investigate CNAs in order to disclose new candidate genes for Wilms tumorigenesis.

RESULTS

Array-CGH of 50 primary WTs without pre-chemotherapy revealed a few recurrent CNAs not previously reported, such as 7q and 20q gains, and 7p loss. Genomic amplifications were exclusively detected in 3 cases of WTs that later relapsed, which also exhibited an increased frequency of gains affecting a 16.2 Mb 1q21.1-q23.2 region, losses at 11p, 11q distal, and 16q, and WT1 deletions. Conversely, aneuploidies of chromosomes 13 and 19 were found only in WTs without further relapse. The 1q21.1-q23.2 gain associated with WT relapse harbours genes such as CHD1L, CRABP2, GJA8, MEX3A and MLLT11 that were found to be over-expressed in WTs. In addition, down-regulation of genes encompassed by focal deletions highlighted new potential tumor suppressors such as CNKSR1, MAN1C1, PAQR7 (1p36), TWIST1, SOSTDC1 (7p14.1-p12.2), BBOX and FIBIN (11p13), and PLCG2 (16q).

CONCLUSION

This study confirmed the presence of CNAs previously related to WT and characterized new CNAs found only in few cases. The later were found in higher frequency in relapsed cases, suggesting that they could be associated with WT progression.

Genetic and chromosomal alterations in Kenyan Wilms Tumor

Wilms tumor (WT) is the most common childhood kidney cancer worldwide and poses a cancer health disparity to black children of sub-Saharan African ancestry. Although overall survival from WT at 5 years exceeds 90% in developed countries, this pediatric cancer is alarmingly lethal in sub-Saharan Africa and specifically in Kenya (36% survival at 2 years). Although multiple barriers to adequate WT therapy contribute to this dismal outcome, we hypothesized that a uniquely aggressive and treatment-resistant biology compromises survival further. To explore the biologic composition of Kenyan WT (KWT), we completed a next generation sequencing analysis targeting 10 WT-associated genes and evaluated whole-genome copy number variation. The study cohort was comprised of 44 KWT patients and their specimens. Fourteen children are confirmed dead at 2 years and 11 remain lost to follow-up despite multiple tracing attempts. TP53 was mutated most commonly in 11 KWT specimens (25%), CTNNB1 in 10 (23%), MYCN in 8 (18%), AMER1 in 5 (11%), WT1 and TOP2A in 4 (9%), and IGF2 in 3 (7%). Loss of heterozygosity (LOH) at 17p, which covers TP53, was detected in 18% of specimens examined. Copy number gain at 1q, a poor prognostic indicator of WT biology in developed countries, was detected in 32% of KWT analyzed, and 89% of these children are deceased. Similarly, LOH at 11q was detected in 32% of KWT, and 80% of these patients are deceased. From this genomic analysis, KWT biology appears uniquely aggressive and treatment-resistant.

Retrospective analysis of FFPE based Wilms' Tumor samples through copy number and somatic mutation related Molecular Inversion Probe Based Array

In this report, retrospectively, we analyzed fifteen histo-pathologically characterized FFPE based Wilms' Tumor (WT) samples following an integrative approach of copy number (CN) and loss of heterozygosity (LOH) imbalances. The isolated-DNA was tested on CN and somatic-mutation related Molecular-Inversion-Probe based-Oncoscan Array™ and was analyzed through Nexus-Express OncoScan-3.0 and 7.0 software. We identified gain of 3p13.0-q29, 4p16.3-14.0, 7, 12p13.33-q24.33, and losses of 1p36.11-q44, 11p15.5-q25, 21q 22.2-22.3 and 22q11.21-13.2 in six samples (W1-6) and validated them in nine more samples (W7-9, W12-15, W17-18). Some observed that discrete deletions (1p, 1q, 10p, 10q, 13q, 20p) were specific to our samples. Maximum-LOH was observed in Ch11 as reported in previous studies. However, LOH was also observed in different regions of Ch7 including some cancer genes. The identified LOH-regions (1q21.2-q21.3, 2p24.1-23.3, 2p24.3-24.3, 3p21.3-21.1, 4p16.3, 7p11.2-p11.1, 7q31.2-31.32, 7q34-q35 and Ch 8) in W1-W6 were also validated in W7-9, W12-15 and W18. In addition, previously reported LOH of 1p and 16q region was also observed in our cases. The proven and novel onco (OG)- and tumor-suppressor genes (TSGs) involved in the CNV regions affected the major pathways like Chromatin Modification, RAS, PI3K; RAS in 14/15 cases, NOTCH/TGF-β and Cell Cycle Apoptosis in 10/15 cases, APC in 9/15 cases and Transcriptional Regulation in 7/15 cases, PI3K and genome maintenance in 6/15 cases. This exhaustive profiling of OG and TG may help in prognosis and diagnosis of the disease after validation of all the relevant results, especially the novel ones, obtained in this research in a larger number of samples.

Nephron sparing surgery (NSS) for unilateral wilms tumor (UWT): the SIOP 2001 experience

BACKGROUND

Total nephrectomy (TN) remains the standard treatment of unilateral Wilms tumors (uWT). The SIOP WT-2001 protocol allowed Nephron Sparing Surgery (NSS) for polar or peripherally non-infiltrating tumors.

AIM

Inventory of the current SIOP NSS-experience.

PROCEDURES

2,800 patients with a unilateral, localized or metastatic and an unequivocal surgical technique recorded were included. All had neo-adjuvant chemotherapy and delayed surgery. In 91 (3%) NSS was performed and in 2709 TN. Data was retrieved from the SIOP WT 2001 database.

RESULTS

NSS group contained 65% stage I tumours and the TN group 48%. Tumor volume (at diagnosis and surgery) was significantly smaller in the NSS group. Within stage III, after NSS, 7/12 (58%) had positive margins (M +), 5 with tumor negative lymph nodes (LN-). After TN, 355/712 (55%) had M + , 182 were LN-. Treatment of M+ in the NSS group resulted in two conversions to TN (one combined with radiotherapy), three patients had radiotherapy only and in two patients local therapy, if given, was not recorded. After NSS, four recurrences occurred. For localized disease the 5-year overall (OS) and event free survival (EFS) in NSS group was 100 and 94.8 (95% CI:89.9-99.9), respectively, while OS and EFS in the TN group were 94.4 (95% CI: 93.2-95.5, log-rank test P = 0.06) and 86.5 (95% CI:85.0-88.1, log-rank test P = 0.06), respectively.

CONCLUSIONS

NSS was only performed in 3% of patients with uWT. Despite excellent survival with few relapses, the gain of nephrons needs to be weighed against the risk to induce stage III with intensified therapy.

Race disparities in peptide profiles of North American and Kenyan Wilms tumor specimens

BACKGROUND

Wilms tumor (WT) is the most common childhood kidney cancer worldwide and arises in children of black African ancestry with greater frequency and severity than other race groups. A biologic basis for this pediatric cancer disparity has not been previously determined. We hypothesized that unique molecular fingerprints might underlie the variable incidence and distinct disease characteristics of WT observed between race groups.

STUDY DESIGN

To evaluate molecular disparities between WTs of different race groups, the Children's Oncology Group provided 80 favorable histology specimens divided evenly between black and white patients and matched for disease characteristics. As a surrogate of black sub-Saharan African patients, we also analyzed 18 Kenyan WT specimens. Tissues were probed for peptide profiles using matrix-assisted laser desorption ionization time of flight imaging mass spectrometry. To control for histologic variability within and between specimens, cellular regions were analyzed separately as triphasic (containing blastema, epithelia, and stroma), blastema only, and stroma only. Data were queried using ClinProTools and statistically analyzed.

RESULTS

Peptide profiles, detected in triphasic WT regions, recognized race with good accuracy, which increased for blastema- or stroma-only regions. Peptide profiles from North American WTs differed between black and white race groups but were far more similar in composition than Kenyan specimens. Individual peptides were identified that also associated with WT patient and disease characteristics (eg, treatment failure and stage). Statistically significant peptide fragments were used to sequence proteins, revealing specific cellular signaling pathways and candidate drug targets.

CONCLUSIONS

Wilms tumor specimens arising among different race groups show unique molecular fingerprints that could explain disparate incidences and biologic behavior and that could reveal novel therapeutic targets.

Association of TP53 polymorphisms on the risk of Wilms tumor

BACKGROUND

Molecular factors influencing Wilms tumor (WT) development remain largely unknown. TP53 mutations seem to be restricted to the anaplastic WT subtype. However, TP53 polymorphisms do not have a defined role in the disease.

PROCEDURE

To assess the impact of TP53 mutations and polymorphisms (PIN2, PIN3, and PEX4) on risk of development, age at diagnosis, and survival in WT, we analyzed 46 blood DNA samples and 31 fresh tumor DNA samples from 52 patients with WT. Sequencing of TP53 exons 2-11 was performed.

RESULTS

Tumor DNA analysis revealed TP53 pathogenic missense mutations (p.V197M, p.R213Q, p.R248W, and p.R337C) in four samples (12.9%). Blood DNA samples revealed a novel intronic mutation, IVS2 + 37C > T, in one patient (2.2%). Bilaterality was associated with a twofold decrease in survival (P = 0.00037). Diffuse anaplasia also presented a lower survival probability compared to patients with non-anaplastic tumors, or with focal anaplasia (P = 0.045). Patients with a TP53 somatic mutation showed survival probability of 37.5% versus 85.0% for patients with no somatic mutations, although the difference was not statistically significant (P = 0.0706). PIN3 duplicated allele was associated with a 20-month later mean age at diagnosis (P = 0.0084). TP53 PEX4 C allele showed an increased risk for WT development (P = 0.0379). No relationship was found between survival and gender, age at diagnosis, or the less frequent alleles of PIN2, PIN3, and PEX4.

CONCLUSIONS

Our results demonstrate an association between PIN3 and age at diagnosis, as well as an association of PEX4 and risk of development of WT.