The UMBRELLA SIOP-RTSG 2016 Wilms tumour pathology and molecular biology protocol

Paediatric renal tumors: An insight into molecular characteristics, histomorphology and syndromic association

Paediatric renal tumors are rare and accounts for about 7% of all paediatric malignant tumors. The spectrum of paediatric renal tumors ranges from benign to malignant. Benign tumors include cystic nephroma, metanephric tumors and ossifying renal tumor of infancy. Tumor with low grade malignancy includes mesoblastic nephroma. Malignant tumors are nephroblastoma, clear cell sarcoma, malignant rhabdoid tumor, anaplastic sarcoma and Ewing sarcoma. Additionally, there are molecularly defined renal tumors, which includes renal cell carcinoma (RCC) with MiT translocations, ALK-rearranged RCC, eosinophilic solid and cystic RCC and SMARCB1- deficient renal medullary carcinoma. These tumors apart from having characteristic clinical presentation and histomorphology, also carry typical molecular mutations and translocations. Certain renal tumors have association with various genetic syndromes such as Beckwith-Weidmann syndrome, Wilm’s tumor, aniridia, genitourinary anomalies and mental retardation syndrome, Denys-Drash syndrome, rhabdoid tumor predisposition syndrome and DICER syndrome. This review article focusses on molecular characteristics, histomorphology and syndromic association of pediatric renal tumors, their immunohistochemical approach to diagnosis with recent updates in molecularly defined renal tumors.

Pathological Insights into Non-Neoplastic Renal Parenchyma in Wilms Tumor: Implications for Nephron-Sparing Surgery

INTRODUCTION

 This study aimed to evaluate the non-neoplastic renal parenchyma in Wilms tumor (WT) and investigate its impact on nephron-sparing surgery (NSS).

MATERIALS AND METHODS

 The non-neoplastic renal parenchyma of WT patients was prospectively collected for pathological examination. The histology of non-neoplastic renal parenchyma was assessed from two perspectives: nephrogenic rests (NRs) and nephrons.

RESULTS

 A total of 46 non-neoplastic renal parenchyma specimens were collected from 42 WT patients. The surgeons assessed the median proportion of non-neoplastic renal parenchyma as 30%, whereas using ellipsoid volume, it was calculated to be 27%. The Youden index of surgeons' assessment peaked at a 15% proportion of non-neoplastic renal parenchyma. The bilateral WT (BWT) group and NSS group exhibited significant differences compared with the unilateral WT group and radical nephrectomy group, respectively, with the BWT group showing a tendency toward thickened basement membrane.

CONCLUSION

 The presence of NRs and endogenous nephron alternations should be given due attention in WT. The probability of abnormalities is low when the proportion of non-neoplastic renal parenchyma exceeds 15%, providing pathological support for expanding the adaptation of NSS.

Emerging, Uncommon, and Aggressive Pediatric Kidney Tumors: An Update and Diagnostic Pitfalls

Although favorable histology Wilms tumors are the most prevalent pediatric renal tumor, the remainder includes a small but diverse and important group of malignant neoplasms. Among these are diffuse anaplastic Wilms tumor, blastemal Wilms tumor, anaplastic sarcoma of kidney, and clear cell sarcoma of kidney. Given their rarity, these tumors may pose diagnostic challenges for pathologists, but accurate diagnosis is essential to ensuring these aggressive tumors are managed appropriately. This article summarizes the salient clinical, histopathological, and molecular features of these uncommon but important tumors.

Multi-Observer Study on Diagnostic Accuracy of Pediatric Renal Tumors Imaged with Higher-Harmonic-Generation Microscopy

BACKGROUND/OBJECTIVES

Wilms tumors, the most common pediatric renal tumors, are heterogeneous and consist of varying amounts of three components: blastema, epithelium, and stroma. Postoperative chemotherapy is tailored based on risk group classification and stage. Due to this heterogeneity, pathologists perform extensive tumor sampling to ensure accurate classification. Higher-harmonic-generation microscopy (HHGM) is an innovative imaging technique that enables rapid visualization of fresh tissue without preparation or staining. This makes it particularly valuable for sample selection, as the tissue can be reused for further analysis. This study aims to evaluate the accuracy of pathologists in distinguishing normal renal tissue, abnormal renal tissue, and three types of pediatric renal tumors, Wilms tumor, renal cell carcinoma, and congenital mesoblastic nephroma, in HHGM images.

METHODS

Twenty-nine samples from eighteen patients with a pediatric renal tumor were imaged using an HHG microscope and subsequently processed for histological analysis. Overview images of the samples were acquired at a rate of 10 s per mm2, while high-quality images took 1 min per mm2. A multi-observer study involving ten international expert pathologists of the SIOP-RTSG was conducted.

RESULTS

Pathologists were able to differentiate between normal and abnormal tissue with 100% (29/29) accuracy and correctly identified tumor versus non-tumor tissue with 97% (28/29) accuracy.

CONCLUSIONS

These results show that HHGM is a highly promising technique for the rapid assessment of pediatric renal tumor samples, particularly for evaluating sample representativeness.

Remaining Challenges in the Treatment of Relapsed Wilms Tumor: Children's Oncology Group and International Society of Paediatric Oncology Perspectives

Wilms tumor (WT) is the most common pediatric renal tumor, and with multidisciplinary treatment overall outcomes are excellent. However, a small subset of patients with WT will relapse. The ideal treatment of relapsed WT is yet to be defined. Ongoing studies through the Children's Oncology Group Renal Tumors Committee (COG-RTC) and the International Society of Paediatric Oncology Renal Tumor Study Group (SIOP-RTSG) aim to improve risk stratification and treatment strategies. Members met at the SIOP 55th Annual Congress 2023 to outline available data and knowledge gaps and develop future research priorities.

18F-Fluorodeoxyglucose positron emission tomography/computed tomography in distinguishing pediatric clear cell sarcoma of the kidney from Wilms' tumor

BACKGROUND

Clear cell sarcoma of the kidney is a rare primary renal malignancy in children and its differentiation from other renal tumors, particularly Wilms' tumor, poses significant diagnostic challenges. Notably, clear cell sarcoma of the kidney is associated with a poorer prognosis than Wilms' tumor, making the preoperative presumptive diagnosis critical for optimizing surgical resection and appropriate chemotherapy regimens.

OBJECTIVE

We conducted a feasibility study to evaluate the diagnostic utility of 18F-fluorodeoxyglucose positron emission tomography/computed tomography (18F-FDG PET/CT) in distinguishing clear cell sarcoma of the kidney from Wilms' tumor.

MATERIALS AND METHODS

This study included 19 patients diagnosed with clear cell sarcoma of the kidney and 84 patients with Wilms' tumor. Among these, 11/19 patients with clear cell sarcoma of the kidney and 28/84 patients of Wilms' tumor displayed positive findings on 18F-FDG PET/CT imaging, which were subsequently validated as tumor lesions by histologic examination, conventional imaging, or clinical follow-up. A retrospective analysis of the imaging features of clear cell sarcoma of the kidney and Wilms' tumor lesions on 18F-FDG PET/CT scans was conducted. Receiver operating characteristic (ROC) curve analyses were performed to determine the optimal cutoff of the maximum standardized uptake value (SUVmax) for diagnostic prediction.

RESULTS

The mean SUVmax for all lesions of clear cell sarcoma of the kidney was significantly lower than that of Wilms' tumors (3.9 vs. 7.4; P<0.001). When analyzed separately, primary lesions (3.6 vs. 6.6; P=0.042) and metastatic lesions (4.0 vs. 7.8; P=0.011) both had lower SUVmax in clear cell sarcomas of the kidney compared with Wilms' tumors. ROC curve analysis revealed a cutoff SUVmax of 4.3, which effectively supported the diagnosis of clear cell sarcoma of the kidney over Wilms' tumor, with a sensitivity of 75.0% and a specificity of 87.5%.

CONCLUSIONS

Clear cell sarcomas of the kidney exhibited a significantly lower SUVmax on 18F-FDG PET/CT when compared to Wilms' tumor lesions, with a proposed threshold SUVmax of 4.3 serving as an effective criterion for differentiation. Consequently, 18F-FDG PET/CT demonstrated potential in distinguishing clear cell sarcoma of the kidney from Wilms' tumor in cases involving large renal masses.

Exploring the in silico adaptation of the Nephroblastoma Oncosimulator to MRI scans, treatment data, and histological profiles of patients from different risk groups

Introduction

Nephroblastoma or Wilms' tumor is the most prevalent type of renal tumor in pediatric oncology. Although the overall survival rate for this condition is excellent today (∼90%), there have been no significant improvements over the past two decades. In silico models aim to simulate tumor progression and treatment responses over time; they hold immense potential for enhancing the predictive accuracy and optimizing treatment protocols as they are inspired by the digital twin paradigm.

Methods

The present study uses T2-weighted magnetic resonance images, chemotherapy treatment plans, and post-surgical histological profiles from three patients enrolled in the SIOP 2001/GPOH clinical trial, where each patient represents a distinct clinically assessed risk group. We investigated the clinical adaptation of the Nephroblastoma Oncosimulator to the datasets from these patients with the goal of deriving appropriate value distributions of the model input parameters that enable accurate prediction of tumor volume reduction in response to preoperative chemotherapy.

Results

Our primary focus was on the total cell kill ratio as a parameter reflecting treatment effectiveness. We derived the distribution of this parameter for one patient from each risk group: low (Mdn = 0.875, IQR [0.750, 0.875], n = 178), intermediate (Mdn = 0.875, IQR [0.750, 0.875], n = 175), and high (Mdn = 0.485, IQR [0.438, 0.532], n = 103). Statistically significant differences were observed between the high-risk group and both the low- and intermediate-risk groups (p < 0.001).

Discussion

The present work establishes a foundation for further studies using available retrospective datasets and additional patients per risk group. These efforts are expected to help validate the findings, advance model development, and extend this mechanistic multiscale discretized cancer model. However, clinical validation is ultimately required to assess the potential uses of the model in clinical decision-support systems.

Data set for reporting paediatric renal tumours: recommendations from the international collaboration on cancer reporting (ICCR)

Tumours arising within the developing kidney of children vary widely in their histological appearance and outcome; optimal therapy requires accurate classification and staging. The two major paediatric cooperative groups provide different therapeutic protocols based on different staging and classification, initially developed to serve patients in North America and Europe, but also used in many other parts/regions of the world. The International Collaboration on Cancer Reporting (ICCR) has developed a structure whereby such complex information may be harmonised, and able to be applied to patients globally. An international expert panel consisting of paediatric pathologists and oncologists produced a set of items critical to cancer reporting and subjected these to review and discussion using the structured processes provided by the ICCR. A formal ICCR structure was assembled, and consensus surrounding elements and their application to different therapeutic protocols was developed. The data set underwent open international consultation. This resulted in the first international data set for Wilms tumour (WT) and other paediatric renal tumours, provided herein. The use of ICCR methods enables a full understanding of highly complex and often overlapping reporting elements by international experts, and the potential of developing a set of commonly applied data elements that are fully defined. This sets the groundwork for future consolidation of definitions and harmonisation of therapies for WT and other paediatric renal tumour patients. It also allows institutions outside the major paediatric cooperative groups to provide therapy based on known elements.

Current surgical approaches to pediatric renal tumors

Pediatric renal tumors are among the most common pediatric solid malignancies. Surgical resection is a key component in the multidisciplinary therapy for children with kidney tumors. Therefore, it is imperative that surgeons caring for children with renal tumors fully understand the current standards of care in order to provide appropriate surgical expertise within this multimodal framework. Fortunately, the last 60 years of international, multidisciplinary pediatric cancer cooperative group studies have enabled high rates of cure for these patients. This review will highlight the international surgical approaches to pediatric patients with kidney cancer to help surgeons understand the key differences and similarities between the European (International Society of Pediatric Oncology) and North American (Children's Oncology Group) recommendations.

Minimally invasive and robotic-assisted approaches applied to pediatric surgical oncology

The management of pediatric tumors is complex, with surgery, chemotherapy, and radiotherapy being cornerstones in their treatment. Tumor removal is increasingly performed by a minimally invasive approach, which allows for quicker postoperative recovery and less postoperative pain. The goal of this report is to give an overview of minimally invasive surgical approaches for common pediatric tumors, with a focus on technical considerations and postoperative outcomes.

Integration of single-nuclei and spatial transcriptomics to decipher tumor phenotype predictive of relapse-free survival in Wilms tumor

Background

Wilms tumor (WT) is the most common childhood renal malignancy, with recurrence linked to poor prognosis. Identifying the molecular features of tumor phenotypes that drive recurrence and discovering novel targets are crucial for improving treatment strategies and enhancing patient outcomes.

Methods

Single-nuclei RNA sequencing (snRNA-seq), spatial transcriptomics (ST), bulk RNA-seq, and mutation/copy number data were curated from public databases. The Seurat package was used to process snRNA-seq and ST data. Scissor analysis was applied to identify tumor subpopulations associated with poor relapse-free survival (RFS). Univariate Cox and LASSO analyses were utilized to reduce features. A prognostic ensemble machine learning model was developed. Immunohistochemistry was used to validate the expression of key features in tumor tissues. The CellChat and Commot package was utilized to infer cellular interactions. The PERCEPTION computational pipeline was used to predict the response of tumor cells to chemotherapy and targeted therapies.

Results

By integrating snRNA-seq and bulk RNA-seq data, we identified a subtype of Scissor+ tumor cells associated with poor RFS, predominantly derived from cap mesenchyme-like blastemal and fibroblast-like tumor subgroups. These cells displayed nephron progenitor signatures and cancer stem cell markers. A prognostic ensemble machine learning model was constructed based on the Scissor+ tumor signature to accurately predict patient RFS. TGFA was identified as the most significant feature in this model and validated by immunohistochemistry. Cellular communication analysis revealed strong associations between Scissor+ tumor cells and cancer-associated fibroblasts (CAFs) through IGF, SLIT, FGF, and PDGF pathways. ST data revealed that Scissor+ tumor cells were primarily located in immune-desert niche surrounded by CAFs. Despite reduced responsiveness to conventional chemotherapy, Scissor+ tumor cells were sensitive to EGFR inhibitors, providing insights into clinical intervention strategies for WT patients at high risk of recurrence.

Conclusion

This study identified a relapse-associated tumor subtype resembling nephron progenitor cells, residing in immune-desert niches through interactions with CAFs. The proposed prognostic model could accurately identify patients at high risk of relapse, offering a promising method for clinical risk stratification. Targeting these cells with EGFR inhibitors, in combination with conventional chemotherapy, may provide a potential therapeutic strategy for WT patients.

A Unique Case of Cystic Partially Differentiated Nephroblastoma Associated With Botryoid Intralobar Nephrogenic Rests

Cystic partially differentiated nephroblastoma (CPDN) is a rare pediatric renal tumor composed of multiple cystic spaces divided by septa containing immature nephrogenic elements. The presence of expansile solid areas in the septa of such a lesion indicates an alternative diagnosis of Wilms tumor (WT). We present a unique case of CPDN associated with grossly visible polypoid proliferations, which histologically correspond to botryoid growth of intralobar nephrogenic rests. Correct pathological diagnosis of CPDN and its differentiation from cystic WT can be challenging, but is critical, because of the distinct treatment approaches and prognoses of these entities, since CPDN is a low-risk tumor not requiring further postoperative therapy.

Fluorescence confocal microscopy for evaluation of fresh surgical specimens and consecutive tumor cell isolation in rare pediatric tumors

Fluorescence confocal microscopy (FCM) is an optical technique that uses laser light sources of different wavelengths to generate real-time images of fresh, unfixed tissue specimens. FCM allows histological evaluation of fresh tissue samples without the associated cryo artifacts after frozen sectioning. The aim of this study was to prospectively evaluate pediatric tumor specimens and assess their suitability for fresh tumor sampling. In addition, we aimed to determine whether tumor cell isolation for stable cell culture is still feasible after FCM imaging. Pediatric tumor specimens were imaged using FCM. Tumor viability and suitability for tissue sampling were evaluated and compared with H&E staining after paraffin embedding. In addition, FCM-processed and non-FCM-processed tissue samples were sent for tumor cell isolation to evaluate possible effects after FCM processing. When comparing estimated tumor cell viability using FCM and H&E, we found good to excellent correlating estimates (intraclass correlation coefficient = 0.891, p < 0.001), as well as substantial agreement in whether the tissue appeared adequate for fresh tissue collection (κ = 0.762, p < 0.001). After FCM, seven out of eight samples yielded passable cell cultures, compared to eight out of eight for non-FCM processed samples. Our study suggests that the use of FCM in tumor sampling can increase the yield of suitable fresh tumor samples by identifying viable tumor areas and ensuring that sufficient tissue remains for diagnosis. Our study also provides first evidence that the isolation and growth of tumor cells in culture are not compromised by the FCM technique.

Pediatric Genitourinary Tumors: The Developmental Angle

Pediatric cancer is relatively rare compared to cancer in adults. Most pediatric neoplasms affect the hemopoietic and central nervous systems. Of the solid extracranial tumors, renal and genitourinary lesions are among the most frequent pediatric neoplasms. Wilms tumors (nephroblastomas) and their variants predominate. Others are less frequent, and their rarity leads to significant diagnostic challenges. This review presents the most important points for diagnosis using histopathological, immunophenotypical, and molecular novel information on the most important renal and genitourinary pediatric neoplasms.

Paediatric Renal Tumors: A State-of-the-Art Review

PURPOSE OF REVIEW

Pediatric renal tumors comprise a wide range of conditions, both malignant and benign, that affect children and require a multidisciplinary approach for optimal diagnosis and treatment. This review offers an in-depth analysis of the epidemiology, diagnosis, treatment options, outcomes, and survival of major pediatric renal tumors.

RECENT FINDINGS

Wilms tumor, or nephroblastoma, is the most common form of renal tumor in children, characterized by growth from primitive renal cells. Standard treatment involves a combination of surgery, chemotherapy and, in some cases, radiation therapy, with the aim of removing the tumor, preventing recurrence and maximizing the chances of long-term recovery. Less common pediatric renal tumors, such as renal clear cell sarcoma, renal cell carcinoma, mesoblastic nephroma, and malignant rhabdoid tumor, require similarly careful and individualized management. Therapeutic strategies, which depend on the characteristics of the tumor, the stage of the disease and the individual response to therapy, may include surgery, chemotherapy, radiotherapy and, in some cases, molecular targeted therapies, immunotherapies and genetic and epigenetic therapies. The management of pediatric kidney tumors requires the involvement of a multidisciplinary team of specialists to ensure accurate evaluation, optimal treatments and long-term follow-up. The aim is to maximize the prospects for recovery and improve the quality of life of patients and their families. Advances in innovative, personalized therapies represent an important opportunity to further improve clinical outcomes in these patients.

Predisposition Footprints in the Somatic Genome of Wilms Tumors

Approximately 10% of children with cancer harbor a mutation in a predisposition gene. In children with the kidney cancer Wilms tumor, the prevalence is as high as 30%. Certain predispositions are associated with defined histological and clinical features, suggesting differences in tumorigenesis. To investigate this, we assembled a cohort of 137 children with Wilms tumor, of whom 71 had a pathogenic germline or mosaic variant. We examined 237 neoplasms (including two secondary leukemias), utilizing whole-genome sequencing, RNA sequencing, and genome-wide methylation, validating our findings in an independent cohort. Tumor development differed in children harboring a predisposition, depending on the variant gene and its developmental timing. Differences pervaded the repertoire of driver events, including high-risk mutations, the clonal architecture of normal kidneys, and the relatedness of neoplasms from the same individual. Our findings indicate that predisposition may preordain Wilms tumorigenesis, suggesting a variant-specific approach to managing children merits consideration. Significance: Tumors that arise in children with a cancer predisposition may develop through the same mutational pathways as sporadic tumors. We examined this question in the childhood kidney cancer, Wilms tumor. We found that certain predispositions dictate the genetic development of tumors, with clinical implications for these children. See related commentary by Brzezinski and Malkin, p. 258.

Wilms tumor primary cultures capture phenotypic heterogeneity and facilitate preclinical screening

Wilms tumors (WT) are characterized by variable contributions of blastemal, epithelial and stromal elements, reflecting their diverse cellular origins and genetic drivers. In vitro models remain rare, despite a growing need to better characterize tumor biology and evaluate new treatments. Using three approaches, we have now established a large collection of long-term cultures that represent this diversity. Adherent WT cultures are predominated by stromal cells, 3D spheroids model blastema, and patient-derived organoid cultures of both tumor and healthy kidney tissue result in the preferential growth of epithelial cells. Adherent, spheroid and organoid cultures are also clearly distinguishable by their transcriptome. Preclinical drug screening experiments revealed sensitivity to a range of inhibitors, that are highly effective in other childhood solid tumors. Sensitivity was related to MYCN status, a marker associated with adverse outcome across human cancers including WT. The combination of the three culture techniques represents a promising tool to both explore tumor heterogeneity in vitro and to facilitate characterization of candidate driver genes, in order to improve treatment regimens in the future.

Direct correlation of MR-DWI and histopathology of Wilms' tumours through a patient-specific 3D-printed cutting guide

OBJECTIVES

The International Society of Paediatric Oncology-Renal Tumour Study Group (SIOP-RTSG) discourages invasive procedures to determine the histology of paediatric renal neoplasms at diagnosis. Therefore, the histological subtype of Wilms' tumours (WT) is unknown at the start of neoadjuvant chemotherapy. MR-DWI shows potential value as a non-invasive biomarker through apparent diffusion coefficients (ADCs). This study aimed to describe MR characteristics and ADC values of paediatric renal tumours to differentiate subtypes.

MATERIALS AND METHODS

Children with a renal tumour undergoing surgery within the SIOP-RTSG 2016-UMBRELLA protocol were prospectively included between May 2021 and 2023. In the case of a total nephrectomy, a patient-specific cutting guide based on the neoadjuvant MR was 3D-printed, allowing a correlation between imaging and histopathology. Whole-tumour volumes and ADC values were statistically compared with the Mann-Whitney U-test. Direct correlation on the microscopic slide level was analysed through mixed model analysis.

RESULTS

Fifty-nine lesions of 54 patients (58% male, median age 3.0 years (range 0-17.7 years)) were included. Forty-four lesions involved a WT. Stromal type WT showed the lowest median decrease in volume after neoadjuvant chemotherapy (48.1 cm3, range 561.5-(+)332.7 cm3, p = 0.035). On a microscopic slide level (n = 240 slides) after direct correlation through the cutting guide, stromal areas showed a significantly higher median ADC value compared to epithelial and blastemal foci (p < 0.001). With a cut-off value of 1.195 * 10-3 mm2/s, sensitivity, and specificity were 95.2% (95% confidence interval 87.6-98.4%) and 90.5% (95% confidence interval 68.2-98.3%), respectively.

CONCLUSION

Correlation between histopathology and MR-DWI through a patient-specific 3D-printed cutting guide resulted in significant discrimination of stromal type WT from epithelial and blastemal subtypes.

CLINICAL RELEVANCE STATEMENT

Stromal Wilms' tumours could be discriminated from epithelial- and blastemal lesions based on high apparent diffusion coefficient values and limited decrease in volume after neoadjuvant chemotherapy. This may aid in future decision-making, especially concerning discrimination between low- and high-risk neoplasms.

KEY POINTS

MR-DWI shows potential value as a non-invasive biomarker in paediatric renal tumours. The patient-specific cutting guide leads to a correlation between apparent diffusion coefficient values and Wilms' tumour subtype. Stromal areas could be discriminated from epithelial and blastemal foci in Wilms' tumours based on apparent diffusion coefficient values.

A refined kidney tumor nephrometry system employed to screen pediatric patients who are eligible for nephron sparing surgery

Purpose

Comprehension of the anatomical characteristics of pediatric kidney tumors is crucial for making surgical decisions. Previous kidney tumor nephrometry systems failed to incorporate two significant factors: tumor thrombus and multifocality. We develop a refined nephrometry system based on a comprehensive understanding of the characteristics exhibited by pediatric kidney tumors.

Methods

The TUMORS nephrometry scoring system comprises 6 indicators, including tumor (T)hrombus, (U)rinary collecting system involvement, (M)ultiple tumors, (O)utward property, (R)adius, and (S)ite relative to the polar lines. Each renal unit was assessed and scored independently. The complexity characteristics of kidney tumors were summarized, and the correlation was compared with RENAL nephrometry system. Furthermore, the complexity of kidney tumors was compared across different surgical procedures.

Results

A total of 43 patients were enrolled, involving 70 kidney units. Radical nephrectomy (RN) was performed on 13 kidneys, while the remaining 57 kidneys underwent nephron sparing surgery. In the NSS group, tumors in 37 kidneys were resected in vivo, whereas 20 kidneys underwent tumor resection ex vivo followed by kidney autotransplantation. According to the TUMORS nephrometry scoring system, there were 13, 34 and 23 kidney units classified as low, moderate and high complexity, respectively. Tumors that underwent RN or ex vivo removal exhibited higher complexity. The complications and positive margins of NSS were not statistically significant in relation to tumor complexity.

Conclusion

The TUMORS nephrometry scoring system holds significant guidance for the decision of surgical protocol and can be applied to the preoperative evaluation.

Paediatric renal tumours: an update on challenges and recent developments

Paediatric renal tumours include a broad range of neoplasms which largely differ, but also overlap to a smaller extent, with adult kidney cancer. These include the embryonal tumour nephroblastoma, which accounts for the majority of cases of kidney cancer in the first decade of life and, despite boasting a cure in ~ 90% cases, still presents clinical challenges in a small proportion of cases. A variety of less common mesenchymal tumours, including the mostly indolent congenital mesoblastic nephroma, clear cell sarcoma of kidney which continues to be associated with poor outcomes for higher stage disease, and the typically lethal malignant rhabdoid tumour, form the bulk of the remaining presentations in the first decade. All three of these represent the intrarenal form of a wider 'family' of genetically related and histologically overlapping entities occurring in soft tissue and other anatomical locations. The latter two are examples of aggressive 'epigenetic' tumours driven by dysregulation of chromatin. In the second decade of life, renal cell carcinoma dominates, and with molecular characterisation many distinct subtypes are now described. Herein we discuss the developments in relation to diagnostic categorisation of paediatric renal cancers and how deeper understanding of the underlying biology is already providing therapeutic opportunity, while also focussing on the challenges that remain for the pathologist.

Comprehensive prognostic gene identification and functional characterization of GRAMD1A in Wilms tumor: development of risk prediction models and therapeutic implications

Background

Wilms tumor (WT) is the most common pediatric kidney cancer, with survival rates exceeding 90% in localized cases. However, advanced or recurrent WT remains difficult to treat due to poor prognosis and limited knowledge of its molecular mechanisms. Gene expression profiling has shown promise in identifying prognostic markers and therapeutic targets. This study aimed to identify key prognostic genes and pathways in WT, construct risk prediction models, and validate their role in tumor progression.

Methods

RNA sequencing and clinical data from 136 WT patients were obtained from the TARGET database. Differential gene expression analysis was conducted using GEO datasets GSE11024 and GSE66405 to compare WT and normal kidney tissues. Identified differentially expressed genes (DEGs) underwent Gene Ontology (GO) and KEGG pathway enrichment analysis to explore biological functions and pathways associated with WT progression. Univariate Cox regression was used to assess the association between DEGs and overall survival (OS) and progression-free survival (PFS). LASSO regression models were developed for risk stratification, and model accuracy was evaluated using time-dependent ROC curves. External validation confirmed key hub genes, while functional assays in WT cell lines (WiT-49) assessed the role of GRAMD1A in tumor behavior.

Results

A total of 3,395 DEGs were identified, with 1,564 upregulated and 1,831 downregulated genes. Enrichment analyses revealed significant pathways involved in cell cycle regulation and metabolic reprogramming. Six key genes (GRAMD1A, PLXNA3, SPR, EBAG9, RBM47, and RIDA) were associated with both OS and PFS. LASSO models demonstrated strong predictive performance, with GRAMD1A identified as a major risk factor. External validation confirmed differential expression, and functional assays showed that GRAMD1A silencing significantly inhibited WT cell viability, proliferation, migration, and invasion.

Conclusions

This study identifies novel prognostic genes and potential therapeutic targets in WT. GRAMD1A, SPR, EBAG9, RBM47, and RIDA play critical roles in WT progression, with GRAMD1A as a key oncogenic factor, offering potential for risk stratification and future therapeutic intervention.

Analysis of Wilms Tumour Epidemiology, Clinicopathological Features and Treatment Outcomes in 84 Moroccan Patients

BACKGROUND

Wilms tumour (WT), the second most reported childhood cancer in Morocco, is a malignant kidney tumour that affects children under 15 years old. Prognosis has improved with the adoption of multimodal treatment. However, data on WT in Morocco remain limited.

AIMS

This study aims to comprehensively describe and analyse the epidemiological, clinicopathological features and treatment outcomes of WT in Moroccan patients, including treatment response and recurrence rates.

METHODS AND RESULTS

A retrospective study involved 84 children under 15 years with WT, treated according to the SIOP protocol and followed at the Paediatric Haematology and Oncology Centre at Children's hospital of Rabat, between January 2014 and February 2018. The median age of participants was 36 months, with a male/female sex ratio of 0.79. Abdominal mass was the primary concern in 55 cases (66%). Five patients (6%) had bilateral WT. Metastatic WT occurred in 21 cases (25%). Stage III was predominant in 33 cases (43%). Twenty cases (26%) had high-risk WT, and IVC tumour thrombus was observed in 12 cases (14%). WT histotype correlated significantly with both sex and tumour localisation (p values of 0.040 and 0.013, respectively). Age correlated significantly with WT extension, overall stage and SIOP histology risk grades (p values of 0.003, 0.003 and 0.045, respectively). Overall stage was statistically related to the occurrence of IVC tumour thrombus (p = 0.002). Over a 5-year span post-nephrectomy, complete remission was achieved in 63 patients (75%), partial remission in one patient (1%), while 19 patients (23%) died and one patient (1%) relapsed.

CONCLUSION

These findings are encouraging for a developing country. However, the elevated rates of Stages III and IVC thrombus in this series are still high, primarily attributed to delays in diagnosis and treatment and the limited number of paediatric haematology and oncology units at the time of the study. Nevertheless, further multicentric research is warranted to enrich Moroccan data and establish a national register for WT cases.

Characteristics and outcome of synchronous bilateral Wilms tumour in the SIOP WT 2001 Study: Report from the SIOP Renal Tumour Study Group (SIOP-RTSG)

BACKGROUND

Among patients with nephroblastoma, those with bilateral disease are a unique population where maximising tumour control must be balanced with preserving renal parenchyma.

METHODS

The SIOP 2001 protocol recommended surgery after neoadjuvant cycle(s) of Dactinomycin and Vincristine (AV) with response-adapted intensification, if needed. Adjuvant treatment was given based on the lesion with the worst histology.

RESULTS

Three hundred and twenty seven patients with stage V disease were evaluable: 174 had bilateral Wilms tumour (BWT), 101 unilateral WT and contralateral nephroblastomatosis (NB) and 52 bilateral nephroblastomatosis. In these three groups, the estimated 5y-EFS was 76.1%, 84.6%, and 74.9%, respectively. AV chemotherapy alone was the successful chemotherapy for 58.7% of all the patients and 65.6% of the non-metastatic patients. Among the 174 patients with BWT, 149 (88.2%) had at least one nephron-sparing surgery. Twenty of 61 bilateral stage I patients were treated with four-week AV postoperatively achieving 94.4% 5y-EFS. At last follow-up, 87% of patients had normal renal function.

CONCLUSIONS

This study demonstrates that AV without anthracyclines is sufficient to achieve NSS and good survival in the majority of patients. For patients with bilateral stage I WT and intermediate risk histology, only four weeks adjuvant AV seems to be sufficient.

CLINICAL TRIAL REGISTRATION

NCT00047138.

UNC13B regulates the sensitivity of Wilms' tumor cells to doxorubicin by modulating lysosomes

Wilms' tumor is a malignant neoplasm where current medical advancements have significantly improved survival rates; however, challenges persist such as the resistance of the tumor to chemotherapy drugs like doxorubicin. This necessitates higher dosages, leading to decreased sensitivity. However, using high doses of doxorubicin can have late effects on the heart. Unc-13 homolog B (UNC13B) may be involved in the drug resistance in several tumors, yet its role in modulating drug sensitivity in Wilms' tumor remains unexplored. UNC13B levels were quantified using reverse transcription-qPCR and Western blotting. The half-maximal inhibitory concentration for doxorubicin, vincristine, and actinomycin-D was determined using CCK-8 assays. Cell cycle and apoptosis were analyzed using flow cytometry, and lysosomal changes were observed using Lyso-Tracker staining. The present study initially evaluated UNC13B expression levels in the Wilms' tumor 17.94 cell line. Additionally, through short hairpin RNA-mediated knockdown, changes in doxorubicin sensitivity in 17.94 Wilms' tumor cells were assessed. Concurrently, preliminary investigations into the role of UNC13B in regulating lysosomes was performed, revealing a significant positive association between UNC13B levels and lysosome formation in the 17.94 cell line. Lysosomes likely serve a role in the sensitivity of Wilms' tumor cell lines to drugs. Elevated UNC13B expression was observed in the 17.94 Wilms' tumor cell line compared to normal kidney cells. UNC13B knockdown also resulted in increased apoptosis levels upon doxorubicin treatment. Immunofluorescence revealed UNC13B localization within cellular vesicles, and its knockdown significantly decreased lysosome levels. Overall, the findings of the present study demonstrate that UNC13B regulates the sensitivity of the Wilms' tumor 17.94 cell line to doxorubicin by modulating lysosome formation within cells. The results suggest that UNC13B is likely an enriched target involved in lysosomal regulation in certain tumors, offering a new approach for optimizing chemotherapy in Wilms' tumor and other cancers with high UNC13B expression.

Pediatric thyroid-like follicular renal cell carcinoma-a post-neuroblastoma case with comprehensive genomic profiling data

Thyroid-like follicular renal cell carcinoma (TLFRCC), an emerging subtype of renal cell carcinoma, presents diagnostic challenges due to its resemblance to normal thyroid tissue. Here, we report a rare case of TLFRCC in a pediatric patient, a demographic rarely affected by this subtype. Histologically resembling a typical TLFRCC, our case exhibited unique features including post-neuroblastoma development, occurrence in a male teenager, and diffuse MelanA expression, which has not been previously reported in TLFRCC. Comprehensive genomic profiling revealed the EWSR1::PATZ1 fusion, confirming its genetic basis. Due to the advanced tumor stage, the patient received combined immunotherapy, and after a 9-month follow-up, remains tumor-free. Our case broadens the diagnostic spectrum of pediatric renal cell carcinomas, highlighting the importance of comprehensive molecular profiling in rare subtypes such as TLFRCC. Further research is needed to better understand TLFRCC's genetic landscape and optimize therapeutic strategies, especially in pediatric populations with evolving treatment protocols.

Radiomics in differential diagnosis of Wilms tumor and neuroblastoma with adrenal location in children

OBJECTIVES

Machine learning methods can be applied successfully to various medical imaging tasks. Our aim with this study was to build a robust classifier using radiomics and clinical data for preoperative diagnosis of Wilms tumor (WT) or neuroblastoma (NB) in pediatric abdominal CT.

MATERIAL AND METHODS

This is a single-center retrospective study approved by the Institutional Ethical Board. CT scans of consecutive patients diagnosed with WT or NB admitted to our hospital from January 2005 to December 2021 were evaluated. Three distinct datasets based on clinical centers and CT machines were curated. Robust, non-redundant, high variance, and relevant radiomics features were selected using data science methods. Clinically relevant variables were integrated into the final model. Dice score for similarity of tumor ROI, Cohen's kappa for interobserver agreement among observers, and AUC for model selection were used.

RESULTS

A total of 147 patients, including 90 WT (mean age 34.78 SD: 22.06 months; 43 male) and 57 NB (mean age 23.77 SD:22.56 months; 31 male), were analyzed. After binarization at 24 months cut-off, there was no statistically significant difference between the two groups for age (p = .07) and gender (p = .54). CT clinic radiomics combined model achieved an F1 score of 0.94, 0.93 accuracy, and an AUC 0.96.

CONCLUSION

In conclusion, the CT-based clinic-radiologic-radiomics combined model could noninvasively predict WT or NB preoperatively. Notably, that model correctly predicted two patients, which none of the radiologists could correctly predict. This model may serve as a noninvasive preoperative predictor of NB/WT differentiation in CT, which should be further validated in large prospective models.

CLINICAL RELEVANCE STATEMENT

CT-based clinic-radiologic-radiomics combined model could noninvasively predict Wilms tumor or neuroblastoma preoperatively.

KEY POINTS

• CT radiomics features can predict Wilms tumor or neuroblastoma from abdominal CT preoperatively. • Integrating clinic variables may further improve the performance of the model. • The performance of the combined model is equal to or greater than human readers, depending on the lesion size.

Wilms Tumor with Vena Caval Intravascular Extension: A Surgical Perspective

Wilms tumor (WT) is the most common kidney tumor in pediatric patients. Intravascular extension of WT above the level of the renal veins is a rare manifestation that complicates surgical management. Patients with intravascular extension are frequently asymptomatic at diagnosis, and tumor thrombus extension is usually diagnosed by imaging. Neoadjuvant chemotherapy is indicated for thrombus extension above the level of the hepatic veins and often leads to thrombus regression, obviating the need for cardiopulmonary bypass in cases of cardiac thrombus at diagnosis. In cases of tumor extension to the retrohepatic cava, neoadjuvant therapy is not strictly indicated, but it may facilitate the regression of tumor thrombi, making resection safer. Hepatic vascular isolation and cardiopulmonary bypass increase the risk of bleeding and other complications when utilized for tumor thrombectomy. Fortunately, WT patients with vena caval with or with intracardiac extension have similar overall and event-free survival when compared to patients with WT without intravascular extension when thrombectomy is successfully performed. Still, patients with metastatic disease at presentation or unfavorable histology suffer relatively poor outcomes. Dedicated pediatric surgical oncology and pediatric cardiothoracic surgery teams, in conjunction with multimodal therapy directed by a multidisciplinary team, are preferred for optimized outcomes in this patient population.

Case report: Metastatic BRAF V600E-mutated adult Wilms' tumor with robust response to BRAF/MEK inhibitor therapy

Nephroblastoma or Wilms' tumor (WT) is the most common pediatric renal malignancy but rare in adults. Treatment protocols for adults are typically extrapolated from pediatric guidelines, but there are no standard guidelines for adults due to the rarity of the disease. However, next-generation sequencing has led to new therapeutic options for adult WT patients. We present the first case to our knowledge of a recurrent adult WT treated with dual BRAF/MEK-targeted therapy, which showed initial robust clinical response and was well tolerated.

Staging and Restaging Pediatric Abdominal and Pelvic Tumors: A Practical Guide

The most common abdominal malignancies diagnosed in the pediatric population include neuroblastoma, Wilms tumor, hepatoblastoma, lymphoma, germ cell tumor, and rhabdomyosarcoma. There are distinctive imaging findings and patterns of spread for each of these tumors that radiologists must know for diagnosis and staging and for monitoring the patient's response to treatment. The multidisciplinary treatment group that includes oncologists, surgeons, and radiation oncologists relies heavily on imaging evaluation to identify the best treatment course and prognostication of imaging findings, such as the image-defined risk factors for neuroblastomas, the PRETreatment EXtent of Disease staging system for hepatoblastoma, and the Ann Arbor staging system for lymphomas. It is imperative for radiologists to be able to correctly indicate the best imaging methods for diagnosis, staging, and restaging of each of these most prevalent tumors to avoid inconclusive or unnecessary examinations. The authors review in a practical manner the most updated key points in diagnosing and staging disease and assessing response to treatment of the most common pediatric abdominal tumors. ©RSNA, 2024 Supplemental material is available for this article.

RAF1 gene fusions are recurrent driver events in infantile fibrosarcoma-like mesenchymal tumors

Infantile fibrosarcomas (IFS) and congenital mesoblastic nephroma (CMN) are rare myofibroblastic tumors of infancy and early childhood commonly harboring the ETV6::NTRK3 gene fusion. IFS/CMN are considered as tumors with an 'intermediate prognosis' as they are locally aggressive, but rarely metastasize, and generally have a favorable outcome. A fraction of IFS/CMN-related neoplasms are negative for the ETV6::NTRK3 gene rearrangement and are characterized by other chimeric proteins promoting MAPK signaling upregulation. In a large proportion of these tumors, which are classified as IFS-like mesenchymal neoplasms, the contributing molecular events remain to be identified. Here, we report three distinct rearrangements involving RAF1 among eight ETV6::NTRK3 gene fusion-negative tumors with an original histological diagnosis of IFS/CMN. The three fusion proteins retain the entire catalytic domain of the kinase. Two chimeric products, GOLGA4::RAF1 and LRRFIP2::RAF1, had previously been reported as driver events in different cancers, whereas the third, CLIP1::RAF1, represents a novel fusion protein. We demonstrate that CLIP1::RAF1 acts as a bona fide oncoprotein promoting cell proliferation and migration through constitutive upregulation of MAPK signaling. We show that the CLIP1::RAF1 hyperactive behavior does not require RAS activation and is mediated by constitutive 14-3-3 protein-independent dimerization of the chimeric protein. As previously reported for the ETV6::NTRK3 fusion protein, CLIP1::RAF1 similarly upregulates PI3K-AKT signaling. Our findings document that RAF1 gene rearrangements represent a recurrent event in ETV6::NTRK3-negative IFS/CMN and provide a rationale for the use of inhibitors directed to suppress MAPK and PI3K-AKT signaling in these cancers. © 2024 The Pathological Society of Great Britain and Ireland.

Contrast-enhanced ultrasound for differentiating benign from malignant focal solid renal lesions in pediatric patients

The contrast-enhanced ultrasound (CEUS) has been mainly applied to adults to differentiate benign and malignant renal lesions, however, the characteristics of CEUS in pediatric has not been as well studied as in adults. In the present work, the eligible pediatric patients who underwent renal CEUS between March 2016 and February 2023 were retrospectively analyzed. It included 20 lesions (median diameter, 8.4 cm; range, 1.8-18.0 cm) from 20 patients (median age, 28.0 months; range, 3.0-212.0 months; 9 boys) in malignant group and 5 lesions (median diameter, 3.8 cm; range, 1.3-7.5 cm) from 5 patients (median age, 25.0 months; range, 0.7-216.0 months; 2 boys) in benign group. The diagnostic performance was assessed. Nonparametric and Chi-square tests were performed. With hyperenhancement plus wash-out, CEUS showed a sensitivity of 95.0% [95% confidence interval (CI): 75.1%, 99.9%], a specificity of 80.0% (CI: 28.4%, 99.5%), a positive predictive value of 95.0% (CI: 75.1%, 99.9%) and a negative predictive value of 80.0% (CI: 28.4%, 99.5%). It suggested that CEUS is a valuable technique for identifying between malignant and benign renal lesions in children.

Loss of heterozygosity for chromosomes 16q in Wilms tumors predicts outcomes: A meta-analysis

BACKGROUND

The research findings suggest that the prognosis of children with Wilms tumor (WT) is affected by various factors. Some scholars have indicated that loss of heterozygosity (LOH) on chromosome 16q is associated with a poor prognosis in patients with WT.

AIM

To further elucidate this relationship, we conducted a meta-analysis.

METHODS

This meta-analysis was registered in INPLASY (INPLASY2023100060). We systematically searched databases including Embase, PubMed, Web of Science, Cochrane, and Google Scholar up to May 31, 2020, for randomized trials reporting any intrapartum fetal surveillance approach. The meta-analysis was performed within a frequentist framework, and the quality and network inconsistency of trials were assessed. Odds ratios and 95%CIs were calculated to report the relationship between event-free survival and 16q LOH in patients with WT.

RESULTS

Eleven cohort studies were included in this meta-analysis to estimate the relationship between event-free survival and 16q LOH in patients with WT (I2 = 25%, P < 0.001). As expected, 16q LOH can serve as an effective predictor of event-free survival in patients with WT (risk ratio = 1.95, 95%CI: 1.52-2.49, P < 0.001).

CONCLUSION

In pediatric patients with WT, there exists a partial correlation between 16q LOH and an unfavorable treatment prognosis. Clinical detection of 16q chromosome LOH warrants increased attention to the patient's prognosis.

Automated segmentation and volume prediction in pediatric Wilms' tumor CT using nnu-net

BACKGROUND

Radiologic volumetric evaluation of Wilms' tumor (WT) is an important indicator to guide treatment decisions. However, due to the heterogeneity of the tumors, radiologists have main-guard differences in diagnosis that can lead to misdiagnosis and poor treatment. The aim of this study was to explore whether CT-based outlining of WT foci can be automated using deep learning.

METHODS

We included CT intravenous phase images of 105 patients with WT and double-blind outlining of lesions by two radiologists. Then, we trained an automatic segmentation model using nnUnet. The Dice similarity coefficient (DSC) and 95th percentile Hausdorff distance (HD95) were used to assess the performance. Next, we optimized the automatic segmentation results based on the ratio of the three-dimensional diameter of the lesion to improve the performance of volumetric assessment.

RESULTS

The DSC and HD95 was 0.83 ± 0.22 and 10.50 ± 8.98 mm. The absolute difference and percentage difference in tumor size was 72.27 ± 134.84 cm3 and 21.08% ± 30.46%. After optimization according to our method, it decreased to 40.22 ± 96.06 cm3 and 10.16% ± 9.70%.

CONCLUSION

We introduce a novel method that enhances the accuracy of predicting WT volume by integrating AI automated outlining and 3D tumor diameters. This approach surpasses the accuracy of using AI outcomes alone and has the potential to enhance the clinical evaluation of pediatric patients with WT. By intertwining AI outcomes with clinical data, this method becomes more interpretive and offers promising applications beyond Wilms tumor, extending to other pediatric diseases.

Wilms Tumor With Raised Serum Alpha-Fetoprotein: Highlighting the Need for Novel Circulating Biomarkers

Wilms tumor (WT) is the commonest cause of renal cancer in children. In Europe, a diagnosis is made for most cases on typical clinical and radiological findings, prior to pre-operative chemotherapy. Here, we describe a case of a young boy presenting with a large abdominal tumor, associated with raised serum alpha-fetoprotein (AFP) levels at diagnosis. Given the atypical features present, a biopsy was taken, and histology was consistent with WT, showing triphasic WT, with epithelial, stromal, and blastemal elements present, and positive WT1 and CD56 immunohistochemical staining. During pre-operative chemotherapy, serial serum AFP measurements showed further increases, despite a radiological response, before a subsequent fall to normal following nephrectomy. The resection specimen was comprised of ~55% and ~45% stromal and epithelial elements, respectively, with no anaplasia, but immunohistochemistry using AFP staining revealed positive mucinous intestinal epithelium, consistent with the serum AFP observations. The lack of correlation between tumor response and serum AFP levels in this case highlights a more general clinical unmet need to identify WT-specific circulating tumor markers.

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

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

Prognostic and predictive biomarkers in paediatric solid tumours

Characterisation of histological, immunohistochemical and molecular prognostic and predictive biomarkers has contributed significantly to precision medicine and better outcomes in the management of paediatric solid tumours. Prognostic biomarkers allow predictions to be made regarding a tumour's aggressiveness and clinical course, whereas predictive biomarkers help determine responses to a specific treatment. This review summarises prognostic biomarkers currently used in the more common paediatric solid tumours, with a brief commentary on the most relevant less common predictive biomarkers. MYCN amplification is the most important genetic alteration in neuroblastoma prognosis, and the histological classification devised by Shimada in 1999 is still used in routine diagnosis. Moreover, a new subgrouping of unfavourable histology neuroblastoma enables immunohistochemical characterisation of tumours with markedly different genetic features and prognosis. The predominant histology and commonly observed cytogenetic abnormalities are recognised outcome predictors in Wilms tumour. Evaluation for anaplasia, which is tightly associated with TP53 gene mutations and poor outcomes, is central in both the International Society of Paediatric Oncology and the Children's Oncology Group approaches to disease classification. Characterisation of distinct genotype-phenotype subclasses and critical mutations has expanded overall understanding of hepatoblastoma outcomes. The C1 subclass hepatoblastoma and CTNNB1 mutations are associated with good prognosis. In contrast, the C2 subclass, NFE2L2 mutations, TERT promoter mutations and high expression of oncofetal proteins and stem cell markers are associated with poor outcomes. Risk stratification in sarcomas is highly variable depending on the entity. The prognosis of rhabdomyosarcoma, for example, primarily depends on histological and molecular characteristics. Advances in our understanding of clinically significant biomarkers will translate into more precise diagnoses, improved risk stratification and more effective and less toxic treatment in this challenging group of patients.

Omission of adjuvant chemotherapy in patients with completely necrotic Wilms tumor stage I and radiotherapy in stage III: The 30-year SIOP-RTSG experience

BACKGROUND

Completely necrotic Wilms tumor (CN-WT) following preoperative chemotherapy has been regarded as low-risk WT since the International Society of Paediatric Oncology (SIOP) 93-01 study, and patients have been treated with reduced postoperative therapy. The aim of the study was to evaluate whether the omission of adjuvant chemotherapy in patients with localized CN-WT stage I and radiotherapy in stage III was safe.

PATIENTS AND METHODS

The retrospective observational study of outcomes of patients diagnosed with localized CN-WT on central pathology review and treated according to the SIOP 93-01 and SIOP-WT-2001 protocols (1993-2022).

RESULTS

There were 125 patients with localized CN-WT: 90 with stage I, 10 with stage II, and 25 with stage III. Sixty-two of 125 (49.6%) patients had a discrepant diagnosis and/or staging between the institutional pathologist and central pathology review. In the group of 90 patients with stage I, postoperative chemotherapy was not given to 41 (46%) patients, whereas 49 patients received postoperative chemotherapy-in the latter group, two patients relapsed, and one of them died. One stage I and one stage II patient developed chemotherapy-induced toxicity and died. Nineteen of 25 patients with stage III received no flank radiotherapy. No stage III patient relapsed or died. The overall 5-year event-free survival (EFS) estimate for the entire cohort (stages I-III) was 96.8% [95% confidence interval, CI: 93.6%-99.6%] and the overall survival (OS) was 97.6% [95% CI: 95.0-100%]. The EFS and OS were 97% and 98%, respectively, for stage I, and 100% for stage III.

CONCLUSION

Omission of postoperative chemotherapy for patients with CN-WT stage I, and radiotherapy for stage III is safe. Rapid central pathology review is required to assign appropriate treatment and avoid treatment-related side effects.

Hallmark discoveries in the biology of Wilms tumour

The modern study of Wilms tumour was prompted nearly 50 years ago, when Alfred Knudson proposed the 'two-hit' model of tumour development. Since then, the efforts of researchers worldwide have substantially expanded our knowledge of Wilms tumour biology, including major advances in genetics - from cloning the first Wilms tumour gene to high-throughput studies that have revealed the genetic landscape of this tumour. These discoveries improve understanding of the embryonal origin of Wilms tumour, familial occurrences and associated syndromic conditions. Many efforts have been made to find and clinically apply prognostic biomarkers to Wilms tumour, for which outcomes are generally favourable, but treatment of some affected individuals remains challenging. Challenges are also posed by the intratumoural heterogeneity of biomarkers. Furthermore, preclinical models of Wilms tumour, from cell lines to organoid cultures, have evolved. Despite these many achievements, much still remains to be discovered: further molecular understanding of relapse in Wilms tumour and of the multiple origins of bilateral Wilms tumour are two examples of areas under active investigation. International collaboration, especially when large tumour series are required to obtain robust data, will help to answer some of the remaining unresolved questions.

Mutational signature, cancer driver genes mutations and transcriptomic subgroups predict hepatoblastoma survival

BACKGROUND

Hepatoblastoma is the most frequent pediatric liver cancer. The current treatments lead to 80% of survival rate at 5 years. In this study, we evaluated the clinical relevance of molecular features to identify patients at risk of chemoresistance, relapse and death of disease.

METHODS

All the clinical data of 86 children with hepatoblastoma were retrospectively collected. Pathological slides were reviewed, tumor DNA sequencing (by whole exome, whole genome or target) and transcriptomic profiling with RNAseq or 300-genes panel were performed. Associations between the clinical, pathological, mutational and transcriptomic data were investigated.

RESULTS

High-risk patients represented 44% of our series and the median age at diagnosis was 21.9 months (range: 0-208). Alterations of the WNT/ß-catenin pathway and of the 11p15.5 imprinted locus were identified in 98% and 74% of the tumors, respectively. Other cancer driver genes mutations were only found in less than 11% of tumors. After neoadjuvant chemotherapy, disease-specific survival and poor response to neoadjuvant chemotherapy were associated with 'Liver Progenitor' (p = 0.00049, p < 0.0001) and 'Immune Cold' (p = 0.0011, p < 0.0001) transcriptomic tumor subtypes, SBS35 cisplatin mutational signature (p = 0.018, p = 0.001), mutations in rare cancer driver genes (p = 0.0039, p = 0.0017) and embryonal predominant histological type (p = 0.0013, p = 0.0077), respectively. Integration of the clinical and molecular features revealed a cluster of molecular markers associated with resistance to chemotherapy and survival, enlightening transcriptomic 'Immune Cold' and Liver Progenitor' as a predictor of survival independent of the clinical features.

CONCLUSIONS

Response to neoadjuvant chemotherapy and survival in children treated for hepatoblastoma are associated with genomic and pathological features independently of the clinical features.

Cytokine Signaling in Pediatric Kidney Tumor Cell Lines WT-CLS1, WT-3ab and G-401

Renal tumors comprise ~7% of all malignant pediatric tumors. Approximately 90% of pediatric kidney tumors comprise Wilms tumors, and the remaining 10% include clear cell sarcoma of the kidney, malignant rhabdoid tumor of the kidney, renal cell carcinoma and other rare renal tumors. Over the last 30 years, the role of cytokines and their receptors has been considerably investigated in both cancer progression and anti-cancer therapy. However, more effective immunotherapies require the cytokine profiling of each tumor type and comprehensive understanding of tumor biology. In this study, we aimed to investigate the activation of signaling pathways in response to cytokines in three pediatric kidney tumor cell lines, in WT-CLS1 and WT-3ab cells (both are Wilms tumors), and in G-401 cells (a rhabdoid kidney tumor, formerly classified as Wilms tumor). We observed that interferon-alpha (IFN-α) and interferon-gamma (IFN-γ) very strongly induced the activation of the STAT1 protein, whereas IL-6 and IFN-α activated STAT3 and IL-4 activated STAT6 in all examined tumor cell lines. STAT protein activation was examined by flow cytometry and Western blot using phospho-specific anti-STAT antibodies which recognize only activated (phosphorylated) STAT proteins. Nuclear translocation of phospho-STAT proteins upon activation with specific cytokines was furthermore confirmed by immunofluorescence. Our results also showed that both IFN-α and IFN-γ caused upregulation of major histocompatibility complex (MHC) class I proteins, however, these cytokines did not have any effect on the expression of MHC class II proteins. We also observed that pediatric kidney tumor cell lines exhibit the functional expression of an additional cytokine signaling pathway, the tumor necrosis factor (TNF)-α-mediated activation of nuclear factor kappa B (NF-κB). In summary, our data show that human pediatric renal tumor cell lines are responsive to stimulation with various human cytokines and could be used as in vitro models for profiling cytokine signaling pathways.

Robotic-assisted laparoscopic surgery for the treatment of Wilms' tumor in children: single-center experience and medium-term outcomes

To report our institutional experience and the medium-term outcomes of utilizing robotic-assisted laparoscopic surgery (RALS) in patients with Wilms' tumor (WT). The robotic surgical interventions include nephron-sparing surgery (RAL-NSS), radical nephrectomy (RAL-RN), and nephrectomy with inferior vena cava thrombectomy (RAL-N-IVCT). We retrospectively collected medical records of WT patients who underwent RALS in our center between August 2019 and February 2022. Patients' baseline demographics, preoperative parameters, and perioperative/postoperative data were recorded and analyzed. Follow-up results were collected to evaluate the oncological outcomes. A total of 12 patients (13 sides) with a median age of 30 (IQR: 19.5-45.5) months were included. All operations were successfully completed without conversion. Seven patients received preoperative chemotherapy. Distribution of surgical interventions was as follows: five patients underwent RAL-RN, five received RAL-NSS, one with bilateral WT underwent concurrent RAL-RN and RAL-NSS, and one received RAL-RN-IVCT post preoperative chemotherapy. Postoperative chemotherapy was conducted in ten patients. The estimated intraoperative blood loss was 27 ± 4.0 ml for the RAL-NSS group, 41.67 ± 12.13 ml for the RAL-RN group, and 350 ml for the RAL-RN-IVCT groups, respectively. The median perioperative serum creatinine levels were 32.5 (IQR: 30.75-39.5) μmol/l preoperatively and 35 (IQR: 31.75-38.5) μmol/l postoperatively, which showed no significant difference. No positive lymph nodes were detected. Postoperative chemotherapy was performed according to the tumor volume and pathological findings. The median follow-up time was 17.5 (15.8-22.3) months. During this interval, neither distant metastasis nor recurrence was identified. Based on our medium-term follow-up observations, RAL-NSS, RAL-RN, and RAL-RN-IVCT exhibit promising feasibility and safety profiles in the therapeutic landscape of WT.

Grossing to reporting of Wilms tumor with emphasis on proper sampling in treatment-naive and postchemotherapy specimens and their clinicopathological correlation with outcome

Context

Emphasis on grossing to reporting for the assessment of histopathological parameters predicting outcomes in Wilms tumor.

Aims

To analyze various clinicopathological parameters that effect outcomes in treatment naïve and post chemotherapy Wilms tumor specimens.

Settings and Design

This was a retrospective observational study.

Subjects and Methods

All patients diagnosed with Wilms tumor between 2012 and 2018 at our institute will be included with their clinical findings, laboratory reports, and radiological findings. The patients will be categorized into two groups based on treatment protocol (Society of Pediatric Oncology (SIOP) or the National Wilms Tumor Study Group/Children's Oncology Group (COG) guidelines) used. Details of Grossing and reporting protocols used for the in pre treatment and post treatment specimens will be analyzed. Follow-up till December 2020 will be analyzed.

Statistical Analysis Used

Chi-square and Fisher's exact tests were used for statistical analysis.

Results

A total of 36 patients with the diagnosis of Wilms tumor were included in the present study. The mean age of presentation was 3.9 ± 0.7 years, and males were more common than females. Most of them presented as abdominal mass and few with isolated hematuria. Twenty-six (72%) patients were treated under SIOP protocol with preoperative neoadjuvant chemotherapy. Ten patients underwent upfront surgery as per COG protocol. In SIOP group patients, the mean tumor size was 9.3cm. Forty percent (n = 10) we mixed histological type followed by blastemal type constituting (32%, n = 8). Regressive and epithelial histological types constituted 16% (n = 4) and 12% (n = 3), respectively. In the SIOP group 72% (n = 19) had no anaplasia and 28% (n = 7) had anaplasia. Fifty seven percent (n = 15) cases were Stage I, followed by 26.9% n = 7) and 11.5% (n = 3) being Stage II and Stage III, respectively. Ten patients underwent upfront surgery as per COG protocol. The mean tumor size among this group was 8 cm ranging from 7 cm to 11 cm. Eight (80%) cases had favorable histology and two cases showed focal anaplasia. Heterologous differentiation is seen in 3 (70%). Out of the 10 cases, one case was Stage I, six were Stage 2, one was Stage III, and two were clinical Stage IV. None of the cases showed either vessel or lymph node metastasis. All the patients received adjuvant chemotherapy postsurgery and were followed up till December 2020 for (at least 3 years). Of 25 patients in the SIOP group, 18 (72%) had complete remission with no radiological evidence of residual disease. Of the 10 patients in the COG group, 6 (70%) had complete remission.

Conclusions

Histopathological evaluation of Wilms tumor is a critical aspect in the management of Wilms tumor, as tumor characteristics are different in the tumors treated under SIOP and COG protocols, which will ultimately affect the prognostic risk stratification. This necessitates the knowledge of the important grossing and reporting of these tumors under the two protocols.

A Gradual Transition Toward Anaplasia in Wilms Tumor Through Tolerance to Genetic Damage

Patients with Wilms tumor (WT) in general have excellent survival, but the prognosis of patients belonging to the subgroup of WT with diffuse anaplasia (DA) is poor due to frequent resistance to chemotherapy. We hypothesized that DA WT cells might undergo changes, such as acquiring a persistent tolerance to DNA damage and copy number aberrations (CNAs), which could eventually lead to their resistance to chemotherapy treatment. Tissue sections from chemotherapy-treated DA WTs (n = 12) were compared with chemotherapy-treated nonanaplastic WTs (n = 15) in a tissue microarray system, enabling analysis of 769 tumor regions. All regions were scored for anaplastic features and immunohistochemistry was used to quantify p53 expression, proliferation index (Ki67), and DNA double-strand breaks (γH2AX). CNAs were assessed by array-based genotyping and TP53 mutations using targeted sequencing. Proliferation index and the frequency of DNA double-strand breaks (γH2AX dot expression) increased with higher anaplasia scores. Almost all (95.6%) areas with full-scale anaplasia had TP53 mutations or loss of heterozygosity, along with an increased amount of CNAs. Interestingly, areas with wild-type TP53 with loss of heterozygosity and only one feature of anaplasia (anaplasia score 1) also had significantly higher proliferation indices, more DNA double-strand breaks, and more CNAs than regions without any anaplastic features (score 0); such areas may be preanaplastic cell populations under selective pressure for TP53 mutations. In conclusion, we suggest that chemoresistance of DA WTs may be partly explained by a high proliferative capability of anaplastic cells, which also have a high burden of double-stranded DNA breaks and CNAs, and that there is a gradual emergence of anaplasia in WT.

A review on optimization of Wilms tumour management using radiomics

Background

Wilms tumour, a common paediatric cancer, is difficult to treat in low- and middle-income countries due to limited access to imaging. Artificial intelligence (AI) has been introduced for staging, detecting, and classifying tumours, aiding physicians in decision-making. However, challenges include algorithm accuracy, translation into conventional diagnosis, reproducibility, and reliability. As AI technology advances, radiomics, an AI tool, emerges to extract tumour morphology and stage information.

Objectives

This review explores the application of radiomics in Wilms tumour management, including its potential in diagnosis, prognosis, and treatment. Additionally, it discusses the future prospects of AI in this field and potential directions for automation-aided Wilms tumour treatment.

Methods

The review analyses various research studies and articles on the use of radiomics in Wilms tumour management. This includes studies on automated deep learning-based classification, interobserver variability in histopathological analysis, and the application of AI in staging, detecting, and classifying Wilms tumours.

Results

The review finds that radiomics offers several promising applications in Wilms tumour management, including improved diagnosis: it helps in classifying Wilms tumours from other paediatric kidney tumours, prognosis prediction: radiomic features can be used to predict both staging and response to preoperative chemotherapy, Treatment response assessment: Radiomics can be used to monitor the response of Wilms and to predict the feasibility of nephron-sparing surgery.

Conclusions

This review concludes that radiomics has the potential to significantly improve the diagnosis, prognosis, and treatment of Wilms tumours. Despite some challenges, such as the need for further research and validation, AI integration in Wilms tumour management offers promising opportunities for improved patient care.

Advances in knowledge

This review provides a comprehensive overview of the potential applications of radiomics in Wilms tumour management and highlights the significant role AI can play in improving patient outcomes. It contributes to the growing body of knowledge on AI-assisted diagnosis and treatment of paediatric cancers.

Cystic partially differentiated nephroblastoma in an 18-month-old girl: a case report

Introduction and importance

Cystic partially differentiated nephroblastoma (CPDN) is a rare cystic tumor that affects the kidney. It has a low potential for malignancy. It usually presents as an abdominal mass. It may be difficult to confirm the diagnosis of CPDN without a histopathological study.

Case presentation

The authors report a case of an 18-month-old girl with abdominal distention, which was noticed by her parents. An abdominal computed tomography scan showed a large multilocular cystic mass arising from the lower pole of the left kidney. A left total nephrectomy was performed. Immature blastemal elements without evidence of malignant cells were observed on histological analysis.

Conclusion

The authors report a case of an 18-month-old girl with CPDN managed by total nephrectomy. CPDN should be considered in the differential diagnosis of patients with cystic renal lesions. The authors would also like to affirm that partial or total nephrectomy should be done in all cases of CPDN and other cystic renal tumors.

Surgery in Bilateral Wilms Tumor-A Single-Center Experience

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

Wilms Tumor in Child With Trisomy 18 and Horseshoe Kidney

Trisomy 18 is associated with several congenital malformations, including horseshoe kidney. It can be full, partial, or mosaic, and mosaicism is often associated with lesser severity and longer life expectancy, placing patients at greater risk of developing neoplasms or malignancies. One common tumor among children with Trisomy 18 is Wilms tumor, which is also associated with renal congenital abnormalities such as horseshoe kidney. We present a case describing the occurrence of these three characteristics: development of Wilms tumor in a patient with Trisomy 18 and a horseshoe kidney and discuss treatment with regards to these conditions.

CCNB1 is a novel prognostic biomarker and promotes proliferation, migration and invasion in Wilms tumor

BACKGROUND

Wilms tumour (WT) is a mixed type of embryonal tumour that usually occurs in early childhood. However, our knowledge of the pathogenesis or progression mechanism of WT is inadequate, and there is a scarcity of beneficial therapeutic strategies.

METHODS

High-throughput RNA sequencing was employed in this study to identify differentially expressed genes (DEGs) in clinical tumor samples and matching normal tissues. The STRING database was utilized to build a protein-protein interaction (PPI) network, and the Cytohubba method was used to identify the top 10 highly related HUB genes. Then, the key genes were further screened by univariate COX survival analysis. Subsequently, the XCELL algorithm was used to evaluate the tumour immune infiltration. RT-PCR, WB, and IF were used to verify the expression level of key genes in clinical tissues and tumour cell lines. Finally, the function of the key gene was further verified by loss-of-function experiments.

RESULTS

We initially screened 1612 DEGs, of which 1030 were up-regulated and 582 were down-regulated. The GO and KEGG enrichment analysis suggested these genes were associated with 'cell cycle', 'DNA replication'. Subsequently, we identified 10 key HUB genes, among them CCNB1 was strongly related to WT patients' overall survival. Multiple survival analyses showed that CCNB1 was an independent indicator of WT prognosis. Thus, we constructed a nomogram of CCNB1 combined with other clinical indicators. Single gene GSEA and immune infiltration analysis revealed that CCNB1 was associated with the degree of infiltration or activation status of multiple immune cells. TIDE analysis indicated that this gene was correlated with multiple key immune checkpoint molecules and TIDE scores. Finally, we validated the differential expression level of CCNB1 in an external gene set, the pan-cancer, clinical samples, and cell lines. CCNB1 silencing significantly inhibited the proliferation, migration, and invasive capabilities of WIT-49 cells, also, promoted apoptosis, and in turn induced G2 phase cell cycle arrest in loss-of-function assays.

CONCLUSION

Our study suggests that CCNB1 is closely related to WT progression and prognosis, and serves as a potential target.

Novel concept of Wilms' tumor development: involvement of pluripotential cells of ureteric bud

It is acknowledged that nephron develops after bilateral induction of the metanephric mesenchyma and branching ureteric bud (UB), and that nephrogenic rest and Wilms' tumor (nephroblastoma) arises from impaired differentiation of metanephric blastema. The aim of this study was to obtain more information on the involvement of UB derivatives in nephrogenic rest and Wilms' tumor. We applied immunohistochemistry to analyze nephrogenic rests and Wilms' tumors with mixed histology, including regressive and blastemal types. We used antibodies recognizing UB tip cells (ROBO1, SLIT2, RET), principal cells (AQP2), α- and β-intercalated cells (SLC26A4, SLC4A1, ATP6V1B1, ATP6V0D2), and their precursors (CA2). Tubules surrounded by tumorous blastemal cells resembling UB tip were positive for RET, ROBO1, and SLIT2 in Wilms' tumor. Moreover, CA2-positive tubular structures and ATP6V1B1- and ATP6V0D2-positive immature non-α- and non-β-intercalated cells were detected in nephrogenic rest and Wilms' tumor. We suggest that Wilms' tumor is more than nephroblastoma and propose a definition that Wilms tumor is a malignant embryonal neoplasm derived from pluripotential cells of nephrogenic blastema and of ureteric bud tip.

Impact of the COVID-19 pandemic on paediatric renal tumour presentation and management, a SIOP renal tumour study group study

BACKGROUND

The COVID-19 pandemic had global catastrophic effects on the management of non-communicable diseases including paediatric cancers. Restrictions during the start of 2020 complicated timely referrals of patients to specialized centres. We aimed to evaluate the pandemic's impact on the number of new diagnoses, disease characteristics and management delay for paediatric renal tumour patients included in the SIOP-RTSG-UMBRELLA study, as compared with data from a historical SIOP-RTSG trial (2005-2009).

METHODS

The number of intensive care admissions, population mobility rates and national lockdown periods/restrictions were used as proxies of the pandemic's severity and impact on societies. Clinical and tumour data were extracted from the SIOP-RTSG-UMBRELLA study and from historical SIOP-RTSG trials.

RESULTS

During the first lockdown in Europe, the number of newly diagnosed patients decreased following restrictions and population immobilisation. Additionally, there was a higher proportion of advanced disease (37% vs. 17% before and after COVID-9, p < 0.001) and larger median tumour volume (559 cm3 vs. 328 and 434 cm3 before and after, p < 0.0001). Also in Brazil, the proportion of advanced disease was higher during the national decrease in mobilisation and start of restrictions (50% and 24% vs. 11% and 18% before and after, p < 0.01). Tumour volume in Brazil was also higher during the first months of COVID-19 (599 cm3 vs. 459 and 514 cm3 ), although not significant (p = 0.17). We did not observe any delays in referral time nor in time to start treatment, even though COVID-19 restrictions may have caused children to reach care later.

CONCLUSION

The COVID-19 pandemic briefly changed the tumour characteristics of children presenting with renal tumours. The longer-term impact on clinical outcomes will be kept under review.