Consensus classification of pediatric hepatocellular tumors: A report from the Children's Hepatic tumors International Collaboration (CHIC).

BACKGROUND: Liver tumors are rare in children with histologic heterogeneity that makes diagnosis challenging. Systematic histopathological review, performed as part of collaborative therapeutic protocols, identified relevant histologic subtypes that are important to distinguish. The Children's Hepatic tumors International Collaboration (CHIC) was established to study pediatric liver tumors on a global scale and led to establishment of a provisional consensus classification for use in international clinical trials. The current study is the validation of this initial classification and first large-scale application by international expert reviewers. PROCEDURE: The CHIC initiative includes data from 1605 children treated on eight multicenter hepatoblastoma (HB) trials. Review of 605 available tumors was performed by seven expert pathologists from three consortia (US, EU, Japan). Cases with discordant diagnoses were collectively reviewed to reach a final consensus diagnosis. RESULTS: Of 599 cases with sufficient material for review, 570 (95.2%) were classified as HB by all consortia, and 29 (4.8%) as non-HB, which included "hepatocellular neoplasm, NOS" and malignant rhabdoid tumors. 453 of 570 HBs were classified as epithelial by final consensus. Some patterns (i.e., small cell undifferentiated, macrotrabecular, cholangioblastic) were selectively identified by reviewers from different consortia. All consortia identified a similar number of mixed epithelial-mesenchymal HB. CONCLUSIONS: This study represents the first large-scale application and validation of the pediatric malignant hepatocellular tumors consensus classification. It is a valuable resource to train future generations of investigators on accurate diagnosis of these rare tumors and provides a framework for further international collaborative studies and refinement of the current classification of pediatric liver tumors.

Undifferentiated sarcoma of the liver: Multicenter international experience of the Cooperative Soft-Tissue Sarcoma Group and Polish Paediatric Solid Tumor Group.

BACKGROUND: Undifferentiated embryonal sarcomas of the liver (UESL) are extremely rare and continue to pose a diagnostic and therapeutic challenge. The aim of the study was to present a multicenter experience of the German CWS and Polish PPSTG groups in the treatment of UESL in children. PROCEDURE: Twenty-five patients were treated according to the CWS-96, CWS-2002, and CYVADIC protocols. Distant metastases were observed in four cases (16%). In four cases, an initial disease presentation mimicked other entities. A pure cystic appearance of liver mass led to misdiagnosis of hydatid cyst in three cases. In one case, laparotomy was performed due to the signs of appendicitis, and bleeding from ruptured liver tumor was found. All these patients were finally diagnosed as UESL. RESULTS: Thirteen patients received preoperative chemotherapy. Partial response was observed in 10 cases. Tumor resection was performed in 20 patients (primary resections, 12; delayed resections-, 8). In five patients, the primary tumor never became operable. The macroscopically complete resection rate was 95% (19/20). Postoperative chemotherapy was given to 20 children. Local radiotherapy was used in three children. After a median follow-up time of 136 months, 17 patients (68%) were alive with no evidence of disease. All children with unresectable tumor and three out of four patients with distant metastases died. The five-year overall survival (OS) rate was 72%. CONCLUSIONS: In summary, a complete tumor excision plays the central role in the treatment of UESL. A cystic presentation of the liver lesion on imaging does not exclude the diagnosis of malignant tumor.

Local Stage Dependent Necessity of Radiation Therapy in Rhabdoid Tumors of the Kidney (RTK).

PURPOSE: Rhabdoid tumor of the kidney (RTK) is one of the most aggressive childhood renal tumors. Overall survival ranges from 22% to 47%. The indication for radiation therapy (RT) in usually very young patients is an ongoing discussion. Recent protocols recommend RT independent of local stage, the latter being a good discriminator in other childhood kidney tumors. In this study, we analyze the evidence for RT in regard to risk factors, including tumor stage. METHODS AND MATERIALS: This study analyzed 58 patients with RTK from Austria, Switzerland, and Germany treated in the framework of 4 consecutive, prospective renal/rhabdoid tumor studies from 1991 to 2014. All treatment protocols included multimodality treatment, including high-intensity chemotherapy, surgery, and RT. RESULTS: Local stage distribution was not applicable, I, II, and III in 1, 6, 11, and 40, respectively. Twenty-nine (50%) patients had stage IV disease at diagnosis. Thirty-seven patients (64%) achieved complete remission, and 49% (18/37) relapsed. Thirty-four patients (60%) patients had progressive disease and died, 17 had local disease, 10 had combined disease, and 7 had distant disease; 2 treatment-related deaths were reported (3%). Twenty-one patients received RT during first-line treatment, 18 of them to all involved sites. Eight of the 34 cases of progressive disease occurred in irradiated patients. The local failure rate of treated patients with local stage II or III disease was 29% (6/18) in patients irradiated to all sites compared with 68% (15/22) in nonirradiated patients. One of 6 stage I patients received RT, and 1 patient experienced distant relapse (2-year progression-free and overall survival both 83% ± 15%). Progression-free survival for local stage II and III disease treated with RT, adjusted for early relapse or treatment abandonment, was 67% ± 11%, compared with 15% ± 7% without RT (P < .0001). CONCLUSION: The 68% local failure rate in nonirradiated patients underlines the importance of local treatment. Our experience supports the use of RT for local control in higher stage disease. In contrast, no local relapse in 6 local stage I patients, including 5 nonirradiated patients, suggests omission of RT in this favorable subset of usually infant patients with RTK.

Treatment and outcome of the patients with rhabdomyosarcoma of the biliary tree: Experience of the Cooperative Weichteilsarkom Studiengruppe (CWS).

BACKGROUND: Biliary rhabdomyosarcoma (RMS) is the most common biliary tumor in children. The management of affected patients contains unique challenges because of the rarity of this tumor entity and its critical location at the porta hepatis, which can make achievement of a radical resection very difficult. METHODS: In a retrospective chart analysis we analysed children suffering from biliary RMS who were registered in three different CWS trials (CWS-96, CWS-2002P, and SoTiSaR registry). RESULTS: Seventeen patients (12 female, 5 male) with a median age of 4.3 years were assessed. The median follow-up was 42.2 months (10.7-202.5). The 5-year overall (OS) and event free survival (EFS) rates were 58% (45-71) and 47% (34-50), respectively. Patients > 10 years of age and those with alveolar histology had the worst prognosis (OS 0%). Patients with botryoid histology had an excellent survival (OS 100%) compared to those with non-botryoid histology (OS 38%, 22-54, p = 0.047). Microscopic complete tumor resection was achieved in almost all patients who received initial tumor biopsy followed by chemotherapy and delayed surgery. CONCLUSION: Positive predictive factors for survival of children with biliary RMS are age ≤ 10 years and botryoid tumor histology. Primary surgery with intention of tumor resection should be avoided.

Position paper: Rationale for the treatment of children with CCSK in the UMBRELLA SIOP-RTSG 2016 protocol.

The International Society of Paediatric Oncology-Renal Tumour Study Group (SIOP-RTSG) has developed a new protocol for the diagnosis, treatment, and follow-up monitoring of childhood renal tumours - the UMBRELLA SIOP-RTSG 2016 protocol (the UMBRELLA protocol). This protocol has been designed to continue international collaboration in the treatment of childhood renal tumours and will be implemented in over 50 different countries. Clear cell sarcoma of the kidney, which is a rare paediatric renal tumour that most commonly occurs in children between 2 and 4 years of age, is specifically addressed in the UMBRELLA protocol.

Treatment and outcome of patients with localized intrathoracic and chest wall rhabdomyosarcoma: a report of the Cooperative Weichteilsarkom Studiengruppe (CWS).

PURPOSE: Rhabdomyosarcoma (RMS) is the most common pediatric soft tissue sarcoma. In 7% of the cases it is localized at the chest wall or intrathoracically. The aim of this study was to analyze the multimodal treatment concepts and outcomes of children suffering from intrathoracic and chest wall RMS treated within three different Cooperative Soft Tissue Sarcoma (CWS) trials and one registry (Soft Tissue Sarcoma Registry, SoTiSaR). METHODS: Data of 51 patients with thoracic RMS enrolled in three different CWS trials (CWS-86, -91, -2002P) and one registry (SoTiSaR) were analyzed retrospectively. Surgery and its influence on outcome were assessed. Median follow-up was 37.5 months (0.9-152.5). RESULTS: Median age of the patients was 8.8 years (range 0-19 years). The 5-year overall survival rate (OS) was 57% (95%-CI 49-65) and the 5-year event-free survival rate (EFS) was 45% (38-52). Thirty-five patients had tumors located at the chest wall (EFS: 51%, 43-59), and 16 patients had intrathoracic tumors (EFS: 26%, 13-39). Seventeen patients with tumors ≤ 5 cm had a better outcome (EFS: 64%, 52-76) compared to patients with tumors larger than 5 cm (EFS: 36%, 27-45). Radiotherapy (RT) significantly improved the survival of patients with alveolar RMS compared to patients with embryonal histology (EFS: 66%, 52-80 vs. 32%, 21-43 p = 0.02). Complete tumor excision during delayed surgery was the main prognostic factor for survival (p = 0.045). CONCLUSION: Thoracic RMS is a rare tumor entity. Completeness of tumor resection significantly improved survival of the patients.

Systemic therapy of aggressive fibromatosis in children and adolescents: Report of the Cooperative Weichteilsarkom Studiengruppe (CWS).

BACKGROUND: Treatment algorithms for patients with aggressive fibromatosis (AF) are challenging. There are limited data available about the use of systemic therapy (ST) in pediatric patients with AF. METHODS: Patient-, tumor-, and treatment-related factors of 90 children and adolescents with AF treated on multiple prospective trials of the Cooperative Weichteilsarkom Studiengruppe (1981-2015) were analyzed with focus on response and outcome of ST. RESULTS: Median age was 9.48 years (0.02-18.05). Primary resection was performed in 54 patients and ST was administered in 29 of 54 patients because of disease progression or relapse. In 35 patients, ST was the initial treatment modality. A secondary resection was performed in 21 of 35 patients after ST. A total of 64 patients received ST, mainly methotrexate and vinblastine (40%) with a median duration of 380 days. The most frequent radiological response to ST was stable disease at 3 months (39%) and partial response at 6 months (53%). Radiotherapy was administered to 15 of 90 patients. One patient remained on observation only. The 5-year overall survival was 100% and the 5-year event-free survival (EFS) was 44%. Patients who had a primary resection showed a 5-year EFS of 35% versus 59% in patients who had received primary ST (P = 0.08). Functional deficiencies as long-term sequelae following resection occurred in 11 patients. At a median follow-up of 5.05 years (0.25-14.88), complete remission was achieved in 51 patients and partial remission in 28 patients. CONCLUSIONS: ST seems appropriate if a primary complete resection is not feasible and at relapse/progression after resection.

High-dose treatment for malignant rhabdoid tumor of the kidney: No evidence for improved survival-The Gesellschaft für Pädiatrische Onkologie und Hämatologie (GPOH) experience.

BACKGROUND: Malignant rhabdoid tumor of the kidney (MRTK) is the most aggressive childhood renal tumor with overall survival (OS) rates ranging from 22% to 42%. Whether high-dose chemotherapy with autologous stem-cell transplantation (HDSCT) in an intensive first-line treatment offers additional benefit is an ongoing discussion. METHODS: A retrospective analysis of all 58 patients with MRTK from Austria, Switzerland, and Germany treated in the framework of consecutive, prospective renal/rhabdoid tumor studies SIOP9/GPO, SIOP93-01/GPOH (where SIOP is International Society of Pediatric Oncology and GPOH is German Society of Pediatric Oncology and Hematology), SIOP2001/GPOH, and European Rhabdoid Tumor Registry from 1991 to 2014. RESULTS: Median age at diagnosis was 11 months. Fifty percent of patients had metastases or multifocal disease at diagnosis (Stage IV). Local stage distribution was as follows: not done/I/II/III-1/6/11/40. Fifteen (26%) patients underwent upfront surgery. Thirty-seven (64%) patients achieved a complete remission, 17 (29%) relapsed, 34 (59%) died of disease progression, and two (3%) died of treatment-related complication. Mean time to the first event was 3.5 months. Two-year EFS/OS (where EFS is event-free survival) for the whole group was 37 ± 6%/38 ± 6%. Metastases/multifocal disease, younger age, and local stage III were associated with significantly inferior survival. Eleven (19%) patients underwent HDSCT (carboplatin + thiotepa, n = 6; carboplatin + etoposide + melphalan, n = 4; others, n = 1); 2-year OS in this group was 60 ± 15% compared to 34 ± 8% in the non-HDSCT group (P = 0.064). However, the time needed from radiologic to histologic diagnosis, stem-cell harvest, and HDSCT must also be taken into account to avoid selection bias by excluding the highest risk group with early progression (<90 days). Thus, 2-year EFS only for patients without progression until day 90 was 60 ± 16% consolidated by HDSCT compared to 62 ± 11% without (P = 0.8). CONCLUSION: Our retrospective analysis suggests comparable outcomes for patients with and without HDSCT, if adjusted for early disease progression.

ETV6-NTRK3 in congenital mesoblastic nephroma: A report of the SIOP/GPOH nephroblastoma study.

BACKGROUND: Congenital mesoblastic nephroma (MN) is a rare pediatric renal tumor representing approximately 5% of all pediatric renal tumors. Three different types of MN are distinguished histologically: classical, cellular, and mixed. A frequent genetic alteration is the translocation t(12;15) resulting in a fusion of the ETV6 gene on 12p13 and the NTRK3 gene on 15p15 that occurs almost exclusively in cellular MN. The aim of this study was to determine translocation status of a large cohort of MN with respect to tumor subtype and outcome. PROCEDURE: In total, clinical data from 111 patients were available. Sixty-seven tumors were classical MN (51%), 29 cellular MN (31%), and 15 were mixed MN (18%). From these 111 cases, 79 were analyzed by FISH and RT-PCR. RESULTS: All classical and mixed MN were translocation negative. Seventeen out of 29 (58%) cellular MN harbored the ETV6-NTRK3 translocation. Five-year relapse-free survival (RFS) and overall survival (OS) were 93.2% and 96.8% for the complete cohort. All seven relapses occurred in translocation negative tumors. Five-year RFS was significantly inferior for cellular and mixed MN compared to classic MN (89%, 80%, and 98%), whereas 5-year OS was similar (93%, 96%, and 98%). Within the group of cellular MN, patients having translocation-positive tumors had a significantly superior RFS (5-year RFS: 100% vs. 73%). CONCLUSION: The majority of cellular MNs harbor the ETV6-NTKR3 gene fusion, whereas all classic- and mixed-type MNs were translocation negative. Within the cellular subgroup, patients having translocation-positive tumors had a significantly superior RFS.

Type, Frequency, and Spatial Distribution of Immune Cell Infiltrates in CNS Germinomas: Evidence for Inflammatory and Immunosuppressive Mechanisms.

Central nervous system germinomas are characterized by a massive immune cell infiltrate. We systematically characterized these immune cells in 28 germinomas by immunophenotyping and image analysis. mRNA expression was analyzed by Nanostring technology and in situ RNA hybridization. Tumor infiltrating lymphocytes (TILs) were composed of 61.8% ± 3.1% (mean ± SE) CD3-positive T cells, including 45.2% ± 3.5% of CD4-positive T-helper cells, 23.4% ± 1.5% of CD8-positive cytotoxic T cells, 5.5% ± 0.9% of FoxP3-positive regulatory T cells, and 11.9% ±1.3% PD-1-positive TILs. B cells accounted for 35.8% ± 2.9% of TILs and plasma cells for 9.3% ± 1.6%. Tumor-associated macrophages consisted of clusters of activated PD-L1-positive macrophages and interspersed anti-inflammatory macrophages expressing CD163. Germinoma cells did not express PD-L1. Expression of genes encoding immune cell markers and cytokines was high and comparable to mRNA levels in lymph node tissue. IFNG and IL10 mRNA was detected in subfractions of TILs and in PD-L1-positive macrophages. Taken together, the strong immune reaction observed in germinomas involves inflammatory as well as various suppressive mechanisms. Expression of PD-1 and PD-L1 and infiltration of cytotoxic T cells are biomarkers predictive of response to anti-PD-1/PD-L1 therapies, constituting a rationale for possible novel treatment approaches.

Position paper: Rationale for the treatment of Wilms tumour in the UMBRELLA SIOP-RTSG 2016 protocol.

The Renal Tumour Study Group of the International Society of Paediatric Oncology (SIOP-RTSG) has developed a new protocol for the diagnosis and treatment of childhood renal tumours, the UMBRELLA SIOP-RTSG 2016 (the UMBRELLA protocol), to continue international collaboration in the treatment of childhood renal tumours. This protocol will support integrated biomarker and imaging research, focussing on assessing the independent prognostic value of genomic changes within the tumour and the volume of the blastemal component that survives preoperative chemotherapy. Treatment guidelines for Wilms tumours in the UMBRELLA protocol include recommendations for localized, metastatic, and bilateral disease, for all age groups, and for relapsed disease. These recommendations have been established by a multidisciplinary panel of leading experts on renal tumours within the SIOP-RTSG. The UMBRELLA protocol should promote international collaboration and research and serve as the SIOP-RTSG best available treatment standard.

TP53 alterations in Wilms tumour represent progression events with strong intratumour heterogeneity that are closely linked but not limited to anaplasia.

TP53 mutations have been associated with anaplasia in Wilms tumour, which conveys a high risk for relapse and fatal outcome. Nevertheless, TP53 alterations have been reported in no more than 60% of anaplastic tumours, and recent data have suggested their presence in tumours that do not fulfil the criteria for anaplasia, questioning the clinical utility of TP53 analysis. Therefore, we characterized the TP53 status in 84 fatal cases of Wilms tumour, irrespective of histological subtype. We identified TP53 alterations in at least 90% of fatal cases of anaplastic Wilms tumour, and even more when diffuse anaplasia was present, indicating a very strong if not absolute coupling between anaplasia and deregulation of p53 function. Unfortunately, TP53 mutations do not provide additional predictive value in anaplastic tumours since the same mutation rate was found in a cohort of non-fatal anaplastic tumours. When classified according to tumour stage, patients with stage I diffuse anaplastic tumours still had a high chance of survival (87%), but this rate dropped to 26% for stages II-IV. Thus, volume of anaplasia or possible spread may turn out to be critical parameters. Importantly, among non-anaplastic fatal tumours, 26% had TP53 alterations, indicating that TP53 screening may identify additional cases at risk. Several of these non-anaplastic tumours fulfilled some criteria for anaplasia, for example nuclear unrest, suggesting that such partial phenotypes should be under special scrutiny to enhance detection of high-risk tumours via TP53 screening. A major drawback is that these alterations are secondary changes that occur only later in tumour development, leading to striking intratumour heterogeneity that requires multiple biopsies and analysis guided by histological criteria. In conclusion, we found a very close correlation between histological signs of anaplasia and TP53 alterations. The latter may precede development of anaplasia and thereby provide diagnostic value pointing towards aggressive disease.

Pediatric NUT-midline carcinoma: Therapeutic success employing a sarcoma based multimodal approach.

A subset of poorly differentiated squamous cell carcinomas, NUT midline carcinomas (NMC) are characterized by a translocation t(15;19)(q13;p13) [ 1 ]. The prognosis is generally dismal [ 2 ] and therapeutic success has been limited to exceptional cases [ 3 ]. We present two cases of pediatric NMC from two different institutions treated according to a multimodal sarcoma approach involving surgery, chemotherapy, and focal radiotherapy. One patient has remained in complete continuous remission for over 6 years, while the other is in CR in early follow-up off therapy. Our proposed multimodal strategy apparently meets the aggressive biologic nature of NMC and should be considered for further evaluation in this context potentially in the setting of a clinical trial.

2017 GPOH Guidelines for Diagnosis and Treatment of Patients with Neuroblastic Tumors.

The clinical course of neuroblastoma is more heterogeneous than any other malignant disease. Most low-risk patients experience regression after limited or even no chemotherapy. However, more than half of high-risk patients die from disease despite intensive multimodal treatment. Precise patient characterization at diagnosis is key for risk-adapted treatment. The guidelines presented here incorporate results from national and international clinical trials to produce recommendations for diagnosing and treating neuroblastoma patients in German hospitals outside of clinical trials.

Strong Expression and Amplification of IGF1R in Pleuropulmonary Blastomas.

Pleuropulmonary blastoma (PPB) is a rare malignant intrathoracic tumor primarily affecting children under 5 years of age. PPBs are histologically divided into 3 subtypes: Type 1 PPBs are composed of multiple cysts, and type 3 is a solid lesion with a variable morphologic appearance. Type 2 has a mixed morphology consisting of cystic and solid areas. The genetics of PPB are poorly understood. We analyzed 16 cases of the Kiel Paediatric Tumor Registry with the diagnosis of PPB by comparative genomic hybridization and confirmed some genetic changes by fluorescence in situ hybridization. Furthermore, we performed immunohistochemistry to evaluate insulin-like growth factor type 1 (IGF1R) protein expression. Frequent findings by comparative genomic hybridization were losses on 4q, 5q, 9p and gains on chromosome 8, 17, and 20q. Genomic amplification was observed in 5 cases, 4 related to 15q25qter and 1 to 1p. Fluorescence in situ hybridization could confirm 7 gains of chromosome 8 (7/16, 44%) and 4 amplifications of the IGF1R-gene on 15q26 (4/16, 25%). All of the tumors with IGF1R amplification were type 3 PPBs. One of the PPBs with gain of chromosome 8 was a type 2 tumor and 6 tumors were type 3 PPBs. All but one PPB showed an IGF1R expression by immunohistochemistry. In our series of 16 PPBs, 25% of the tumors have an amplification of the IGF1R gene and 44% show a gain of chromosome 8. All of the tumors with IGF1R amplification were PPBs type 3, indicating that it is a later event in tumor progression, while the gain of chromosome 8 was found in both type 2 and type 3 tumors indicating that these changes are probably earlier events in tumor development. Furthermore, the strong IGF1R protein expression could be a possible therapeutic target in refractory chemoresistant PPBs.

Childhood cancer predisposition syndromes-A concise review and recommendations by the Cancer Predisposition Working Group of the Society for Pediatric Oncology and Hematology.

Heritable predisposition is an important cause of cancer in children and adolescents. Although a large number of cancer predisposition genes and their associated syndromes and malignancies have already been described, it appears likely that there are more pediatric cancer patients in whom heritable cancer predisposition syndromes have yet to be recognized. In a consensus meeting in the beginning of 2016, we convened experts in Human Genetics and Pediatric Hematology/Oncology to review the available data, to categorize the large amount of information, and to develop recommendations regarding when a cancer predisposition syndrome should be suspected in a young oncology patient. This review summarizes the current knowledge of cancer predisposition syndromes in pediatric oncology and provides essential information on clinical situations in which a childhood cancer predisposition syndrome should be suspected.

The impact of local control in the treatment of type II/III pleuropulmonary blastoma. Experience of the Cooperative Weichteilsarkom Studiengruppe (CWS).

BACKGROUND AND OBJECTIVES: This study aims at examining the potential survival benefits of primary versus secondary surgery in the management of children diagnosed with pleuropulmonary blastoma (PPB) type II/III. PATIENTS AND METHODS: Disease characteristics, treatment, and survival of 29 children with localized PPB type II/III, treated in six prospective Cooperative Weichteilsarkom Studiengruppe (CWS) trials, were reviewed retrospectively. RESULTS: Five year event free survival (EFS) and overall survival (OS) of children treated according to CWS protocols was 72%. Patients with tumors ≤10 cm had a 5 year OS of 91% versus 57% in patients with tumors >10 cm (P = 0.025). Five year OS of patients with macroscopically incomplete upfront resections was 44% as opposed to 68% in patients with delayed/secondary microscopically or macroscopically complete resection after an initial biopsy (P = 0.476). Ten patients died of disease, one patient died of second malignancy. Tumor size and complete tumor resection at any time were significant prognostic factors (P = 0.025/0.003) for EFS. EFS for microscopically complete, microscopically incomplete, and macroscopically incomplete resection at any time was 91%, 90%, and 25%, respectively (P = 0.01). CONCLUSIONS: Primary or secondary microscopically/macroscopically complete tumor resections in combination with chemotherapy correlates with long term survival in children with PPB. J. Surg. Oncol. 2017;115:164-172. © 2017 Wiley Periodicals, Inc.

LEF1 reduces tumor progression and induces myodifferentiation in a subset of rhabdomyosarcoma.

Rhabdomyosarcoma (RMS) is the most common soft tissue sarcoma in children and show characteristics of skeletal muscle differentiation. The two major RMS subtypes in children are alveolar (ARMS) and embryonal RMS (ERMS). We demonstrate that approximately 50% of ARMS and ERMS overexpress the LEF1/TCF transcription factor LEF1 when compared to normal skeletal muscle and that LEF1 can restrain aggressiveness especially of ARMS cells. LEF1 knockdown experiments in cell lines reveal that depending on the cellular context, LEF1 can induce pro-apoptotic signals. LEF1 can also suppress proliferation, migration and invasiveness of RMS cells both in vitro and in vivo. Furthermore, LEF1 can induce myodifferentiation of the tumor cells. This may involve regulation of other LEF1/TCF factors i.e. TCF1, whereas ß-catenin activity plays a subordinate role. Together these data suggest that LEF1 rather has tumor suppressive functions and attenuates aggressiveness in a subset of RMS.

The prognostic impact of SYT-SSX fusion type and histological grade in pediatric patients with synovial sarcoma treated according to the CWS (Cooperative Weichteilsarkom Studie) trials.

BACKGROUND: The aim of our analysis was the evaluation of the prognostic impact of SYT-SSX fusion status and histological grading in synovial sarcoma (SS) of children and adolescents in the context of the consistent multimodal treatment strategy of the CWS (Cooperative Weichteilsarkom Studie; Cooperative Soft Tissue Sarcoma Study Group) and in comparison with other risk factors. PROCEDURE: Between 1986 and 2006, out of 243 patients with SS, tumor samples from 84 patients with localized disease were available for RT-PCR analysis. Outcome depending on fusion status in the context with known clinical risk factors was analyzed. RESULTS: No prognostic significance was shown for SYT-SSX fusion status and for histological grade. Highest significance of negative prognostic impact was found for large tumor size in uni- and multivariate analysis (P < 0.01). Furthermore, male gender was shown to be an adverse prognostic factor in multivariate analysis (P = 0.01). CONCLUSIONS: Based on our results, neither histological grading nor SYT-SSX fusion status seems to be suitable for outcome prediction and risk stratification in localized SS treated according to the CWS. This is in contrast to several other publications concerning more heterogeneous age groups including children and adults, and this indicates that prognostic factors should not be interpreted apart from the particular study population and the therapeutic context.

Risk-stratified staging in paediatric hepatoblastoma: a unified analysis from the Children's Hepatic tumors International Collaboration.

BACKGROUND: Comparative assessment of treatment results in paediatric hepatoblastoma trials has been hampered by small patient numbers and the use of multiple disparate staging systems by the four major trial groups. To address this challenge, we formed a global coalition, the Children's Hepatic tumors International Collaboration (CHIC), with the aim of creating a common approach to staging and risk stratification in this rare cancer. METHODS: The CHIC steering committee-consisting of leadership from the four major cooperative trial groups (the International Childhood Liver Tumours Strategy Group, Children's Oncology Group, the German Society for Paediatric Oncology and Haematology, and the Japanese Study Group for Paediatric Liver Tumours)-created a shared international database that includes comprehensive data from 1605 children treated in eight multicentre hepatoblastoma trials over 25 years. Diagnostic factors found to be most prognostic on initial analysis were PRETreatment EXTent of disease (PRETEXT) group; age younger than 3 years, 3-7 years, and 8 years or older; α fetoprotein (AFP) concentration of 100 ng/mL or lower and 101-1000 ng/mL; and the PRETEXT annotation factors metastatic disease (M), macrovascular involvement of all hepatic veins (V) or portal bifurcation (P), contiguous extrahepatic tumour (E), multifocal tumour (F), and spontaneous rupture (R). We defined five clinically relevant backbone groups on the basis of established prognostic factors: PRETEXT I/II, PRETEXT III, PRETEXT IV, metastatic disease, and AFP concentration of 100 ng/mL or lower at diagnosis. We then carried the additional factors into a hierarchical backwards elimination multivariable analysis and used the results to create a new international staging system. RESULTS: Within each backbone group, we identified constellations of factors that were most predictive of outcome in that group. The robustness of candidate models was then interrogated using the bootstrapping procedure. Using the clinically established PRETEXT groups I, II, III, and IV as our stems, we created risk stratification trees based on 5 year event-free survival and clinical applicability. We defined and adopted four risk groups: very low, low, intermediate, and high. INTERPRETATION: We have created a unified global approach to risk stratification in children with hepatoblastoma on the basis of rigorous statistical interrogation of what is, to the best of our knowledge, the largest dataset ever assembled for this rare paediatric tumour. This achievement provides the structural framework for further collaboration and prospective international cooperative study, such as the Paediatric Hepatic International Tumour Trial (PHITT). FUNDING: European Network for Cancer Research in Children and Adolescents, funded through the Framework Program 7 of the European Commission (grant number 261474); Children's Oncology Group CureSearch grant contributed by the Hepatoblastoma Foundation; Practical Research for Innovative Cancer Control and Project Promoting Clinical Trials for Development of New Drugs and Medical Devices, Japan Agency for Medical Research; and Swiss Cancer Research grant.