Indications and results of diagnostic biopsy in pediatric renal tumors: A retrospective analysis of 317 patients with critical review of SIOP guidelines.

OBJECTIVES: According to the Renal Tumor Study Group (RTSG) of the International Society of Paediatric Oncology (SIOP), diagnostic biopsy of renal tumors prior to neoadjuvant chemotherapy is not mandatory unless the presentation is atypical for a Wilms tumor (WT). This study addresses the relevance of this strategy as well as the accuracy and safety of image-guided needle biopsy. METHODS: Clinical, radiological, and pathological data from 317 children (141 males/176 females, mean age: 4 years, range, 0-17.6) consecutively treated in one SIOP-affiliated institution were retrospectively analyzed. RESULTS: Presumptive chemotherapy for WT was decided for 182 patients (57% of the cohort), 24 (8%) were operated upfront, and 111 (35%) were biopsied at diagnosis. A non-WT was confirmed after surgery in 5/182 (3%), 11/24 (46%), and 28/111 (25%), respectively. Age at diagnosis was the most commonly (46%) used criterion to go for biopsy but a nine-year threshold should be retrospectively considered more relevant. Tumor volumes of clear cell sarcoma of the kidney and WT were significantly higher than those of other tumors (P = 0.002). The agreement between core-needle biopsy (CNB) and final histology was 99%. No significant morbidity was associated with CNB. CONCLUSION: The use of SIOP criteria to identify patients eligible for presumptive WT neoadjuvant chemotherapy or upfront surgery avoided biopsy in 65% of children and led to a 97% rate of appropriate preoperative chemotherapy. Image-guided CNB is a safe and accurate diagnostic procedure. The relevance of SIOP biopsy criteria might be improved by using an older age threshold (9 years instead of 6 years) and by adding initial tumor volume.

Influence of segmental chromosome abnormalities on survival in children over the age of 12 months with unresectable localised peripheral neuroblastic tumours without MYCN amplification.

BACKGROUND: The prognostic impact of segmental chromosome alterations (SCAs) in children older than 1 year, diagnosed with localised unresectable neuroblastoma (NB) without MYCN amplification enrolled in the European Unresectable Neuroblastoma (EUNB) protocol is still to be clarified, while, for other group of patients, the presence of SCAs is associated with poor prognosis. METHODS: To understand the role of SCAs we performed multilocus/pangenomic analysis of 98 tumour samples from patients enrolled in the EUNB protocol. RESULTS: Age at diagnosis was categorised into two groups using 18 months as the age cutoff. Significant difference in the presence of SCAs was seen in tumours of patients between 12 and 18 months and over 18 months of age at diagnosis, respectively (P=0.04). A significant correlation (P=0.03) was observed between number of SCAs per tumour and age. Event-free (EFS) and overall survival (OS) were calculated in both age groups, according to both the presence and number of SCAs. In older patients, a poorer survival was associated with the presence of SCAs (EFS=46% vs 75%, P=0.023; OS=66.8% vs 100%, P=0.003). Moreover, OS of older patients inversely correlated with number of SCAs (P=0.002). Finally, SCAs provided additional prognostic information beyond histoprognosis, as their presence was associated with poorer OS in patients over 18 months with unfavourable International Neuroblastoma Pathology Classification (INPC) histopathology (P=0.018). CONCLUSIONS: The presence of SCAs is a negative prognostic marker that impairs outcome of patients over the age of 18 months with localised unresectable NB without MYCN amplification, especially when more than one SCA is present. Moreover, in older patients with unfavourable INPC tumour histoprognosis, the presence of SCAs significantly affects OS.

Treatment and outcome of patients with relapsed clear cell sarcoma of the kidney: a combined SIOP and AIEOP study.

BACKGROUND: Clear cell sarcoma of the kidney (CCSK) is an uncommon paediatric renal tumour. Relapses occur in about 15% of the patients. Since detailed clinical information on relapsed CCSK is scarce, the current study aims to describe outcome of patients with relapsed CCSK treated according to recent European protocols. PATIENTS AND METHODS: We analysed prospectively collected data of all CCSK patients who developed a relapse after complete remission at the end of primary treatment, entered onto SIOP and AIEOP trials between 1992 and 2012. RESULTS: Thirty-seven of 237 CCSK patients (16%) treated according to SIOP and AIEOP protocols developed a relapse. Median time from initial diagnosis to relapse was 17 months (range, 5.5 months - 6.6 years). Thirt-five out of thirty-seven relapses (95%) were metastatic; the most common sites of relapse were the brain (n=13), lungs (n=7) and bone (n=5). Relapse treatment consisted of chemotherapy (n=30), surgery (n=19) and/or radiotherapy (n=18), followed by high-dose chemotherapy and autologous bone marrow transplantation (ABMT) in 14 patients. Twenty-two out of thirty-seven patients (59%) achieved a second complete remission (CR); 15 of whom (68%) developed a second relapse. Five-year event-free survival (EFS) after relapse was 18% (95% CI: 4%-32%), and 5-year overall survival (OS) was 26% (95% CI: 10%-42%). CONCLUSIONS: In this largest series of relapsed CCSK patients ever described, overall outcome is poor. Most relapses are metastatic and brain relapses are more common than previously recognised. Intensive treatment aiming for local control, followed by high dose chemotherapy and ABMT, seems to be of benefit to enhance survival. Novel development of targeted therapy is urgently required.

Malformations, genetic abnormalities, and Wilms tumor.

BACKGROUND: Wilms Tumor (WT) can occur in association with tumor predisposition syndromes and/or with clinical malformations. These associations have not been fully characterized at a clinical and molecular genetic level. This study aims to describe clinical malformations, genetic abnormalities, and tumor predisposition syndromes in patients with WT and to propose guidelines regarding indications for clinical and molecular genetic explorations. PROCEDURE: This retrospective study analyzed clinical abnormalities and predisposition syndromes among 295 patients treated for WT between 1986 and 2009 in a single pediatric oncological center. RESULTS: Clinically identified malformations and predisposition syndromes were observed in 52/295 patients (17.6%). Genetically proven tumor predisposition syndromes (n = 14) frequently observed were syndromes associated with alterations of the chromosome WT1 region such as WAGR (n = 6) and Denys-Drash syndromes (n = 3), syndromes associated with alterations of the WT2 region (Beckwith-Wiedeman syndrome, n = 3), and Fanconi anemia (n = 2). Hemihypertrophy and genito-urinary malformations (n = 12 and n = 16, respectively) were the most frequently identified malformations. Other different syndromes or malformations (n = 10) were less frequent. Median age of WT diagnosis was significantly earlier for children with malformations than those without (27 months vs. 37 months, P = 0.0009). There was no significant difference in terms of 5-year EFS and OS between WT patients without or with malformations. CONCLUSIONS: The frequency of malformations observed in patients with WT underline the need of genetic counseling and molecular genetic explorations for a better follow-up of these patients, with a frequently good outcome. A decisional tree, based on clinical observations of patients with WT, is proposed to guide clinicians for further molecular genetic explorations.

Clear cell sarcomas of the kidney registered on International Society of Pediatric Oncology (SIOP) 93-01 and SIOP 2001 protocols: a report of the SIOP Renal Tumour Study Group.

PURPOSE: Clear Cell Sarcoma of the Kidney (CCSK) is a rare childhood renal tumour. Only a few homogeneously treated CCSK cohorts have been reported. This study aims to describe clinical characteristics and survival of CCSK patients treated according to recent International Society of Pediatric Oncology (SIOP) protocols. PATIENTS AND METHODS: We analysed the prospectively collected data of patients with a histologically verified CCSK, entered onto SIOP 93-01/2001 trials. RESULTS: A total of 191 CCSK patients (64% male) were analysed, with a median age at diagnosis of 2.6 years. Stage distribution for stages I, II, III and IV was 42%, 23%, 28% and 7%, respectively. Pre-operative chemotherapy was administered to 169/191 patients. All patients underwent total nephrectomy and 189/191 patients received post-operative chemotherapy. Radiotherapy was applied in 2/80 stage I, 33/44 stage II, 44/54 stage III and 6/13 stage IV patients. Five year event-free survival (EFS) and overall survival (OS) were 79% (95% confidence interval (CI): 73-85%) and 86% (95% CI: 80-92%) respectively. Stage IV disease and young age were significant adverse prognostic factors for event-free survival. Factors such as gender, tumour volume and type of initial treatment were not found to be prognostic for EFS and OS. CONCLUSION: In this largest SIOP cohort described so far, overall outcome of CCSK is reasonable, although treatment of young and advanced-stage disease patients is challenging. As further intensification of treatment is hampered by direct and late toxicity, future directions should include the development of targeted therapy based on specific molecular aberrations of CCSK.

Segmental chromosomal alterations have prognostic impact in neuroblastoma: a report from the INRG project.

BACKGROUND: In the INRG dataset, the hypothesis that any segmental chromosomal alteration might be of prognostic impact in neuroblastoma without MYCN amplification (MNA) was tested. METHODS: The presence of any segmental chromosomal alteration (chromosome 1p deletion, 11q deletion and/or chromosome 17q gain) defined a segmental genomic profile. Only tumours with a confirmed unaltered status for all three chromosome arms were considered as having no segmental chromosomal alterations. RESULTS: Among the 8800 patients in the INRG database, a genomic type could be attributed for 505 patients without MNA: 397 cases had a segmental genomic type, whereas 108 cases had an absence of any segmental alteration. A segmental genomic type was more frequent in patients >18 months and in stage 4 disease (P<0.0001). In univariate analysis, 11q deletion, 17q gain and a segmental genomic type were associated with a poorer event-free survival (EFS) (P<0.0001, P=0.0002 and P<0.0001, respectively). In multivariate analysis modelling EFS, the parameters age, stage and a segmental genomic type were retained in the model, whereas the individual genetic markers were not (P<0.0001 and RR=2.56; P=0.0002 and RR=1.8; P=0.01 and RR=1.7, respectively). CONCLUSION: A segmental genomic profile, rather than the single genetic markers, adds prognostic information to the clinical markers age and stage in neuroblastoma patients without MNA, underlining the importance of pangenomic studies.

Segmental chromosomal alterations lead to a higher risk of relapse in infants with MYCN-non-amplified localised unresectable/disseminated neuroblastoma (a SIOPEN collaborative study).

BACKGROUND: In neuroblastoma (NB), the presence of segmental chromosome alterations (SCAs) is associated with a higher risk of relapse. METHODS: In order to analyse the role of SCAs in infants with localised unresectable/disseminated NB without MYCN amplification, we have performed an array CGH analysis of tumours from infants enrolled in the prospective European INES trials. RESULTS: Tumour samples from 218 out of 300 enroled patients could be analysed. Segmental chromosome alterations were observed in 11%, 20% and 59% of infants enroled in trials INES99.1 (localised unresectable NB), INES99.2 (stage 4s) and INES99.3 (stage 4) (P<0.0001). Progression-free survival was poorer in patients whose tumours harboured SCA, in the whole population and in trials INES99.1 and INES99.2, in the absence of clinical symptoms (log-rank test, P=0.0001, P=0.04 and P=0.0003, respectively). In multivariate analysis, a SCA genomic profile was the strongest predictor of poorer progression-free survival. CONCLUSION: In infants with stage 4s MYCN-non-amplified NB, a SCA genomic profile identifies patients who will require upfront treatment even in the absence of other clinical indication for therapy, whereas in infants with localised unresectable NB, a genomic profile characterised by the absence of SCA identifies patients in whom treatment reduction might be possible. These findings will be implemented in a future international trial.

An integrative genomics screen uncovers ncRNA T-UCR functions in neuroblastoma tumours.

Different classes of non-coding RNAs, including microRNAs, have recently been implicated in the process of tumourigenesis. In this study, we examined the expression and putative functions of a novel class of non-coding RNAs known as transcribed ultraconserved regions (T-UCRs) in neuroblastoma. Genome-wide expression profiling revealed correlations between specific T-UCR expression levels and important clinicogenetic parameters such as MYCN amplification status. A functional genomics approach based on the integration of multi-level transcriptome data was adapted to gain insights into T-UCR functions. Assignments of T-UCRs to cellular processes such as TP53 response, differentiation and proliferation were verified using various cellular model systems. For the first time, our results define a T-UCR expression landscape in neuroblastoma and suggest widespread T-UCR involvement in diverse cellular processes that are deregulated in the process of tumourigenesis.

Targeted agents in metastatic Xp11 translocation/TFE3 gene fusion renal cell carcinoma (RCC): a report from the Juvenile RCC Network.

BACKGROUND: Xp11 translocation renal cell carcinoma (RCC) is an RCC subtype affecting 15% of RCC patients <45 years. We analyzed the benefit of targeted therapy [vascular endothelial growth factor receptor (VEGFR)-targeted agents and/or mammalian target of rapamycin (mTOR) inhibitors] in these patients. PATIENTS AND METHODS: Patients with Xp11 translocation/TFE3 fusion gene metastatic RCC who had received targeted therapy were identified. Nuclear TFE3 positivity was confirmed by reviewing pathology slides. Responses according to RECIST criteria, progression-free survival (PFS), and overall survival (OS) were analyzed. RESULTS: Overall, 53 patients were identified; 23 had metastatic disease, and of these 21 had received targeted therapy (median age 34 years). Seven patients achieved an objective response. In first line, median PFS was 8.2 months [95% confidence interval (CI) 2.6-14.7 months] for sunitinib (n = 11) versus 2 months (95% CI 0.8-3.3 months) for cytokines (n = 9) (log-rank P = 0.003). Results for further treatment (second, third, or fourth line) were as follows: all three patients receiving sunitinib had a partial response (median PFS 11 months). Seven of eight patients receiving sorafenib had stable disease (median PFS 6 months). One patient receiving mTOR inhibitors had a partial response and six patients had stable disease. Median OS was 27 months with a 19 months median follow-up. CONCLUSION: In Xp11 translocation RCC, targeted therapy achieved objective responses and prolonged PFS similar to those reported for clear-cell RCC.

Molecular pathogenesis of peripheral neuroblastic tumors.

Neuroblastoma (NB) is an embryonal cancer of the sympathetic nervous system observed in early childhood, characterized by a broad spectrum of clinical behaviors, ranging from spontaneous regression to fatal outcome despite aggressive therapies. NB accounts for 8-10% of pediatric cancers and 15% of the deaths attributable to malignant conditions in children. Interestingly, NB may occur in various contexts, being mostly sporadic but also familial or syndromic. This review focuses on recent advances in the identification of the genes and mechanisms implicated in NB pathogenesis. Although the extensive characterization of the genomic aberrations recurrently observed in sporadic NBs provides important insights into the understanding of the clinical heterogeneity of this neoplasm, analysis of familial and syndromic cases also unravels essential clues on the genetic bases of NB. Recently, the ALK gene emerged as an important NB gene, being implicated both in sporadic and familial cases. The identification of gene expression signatures associated with patient's outcome points out the potential of using gene expression profiling to improve clinical management of patients suffering from NB. Finally, based on recent observations integrating genomic analyses, biological data and clinical information, we discuss possible evolution/progression schemes in NB.

International consensus for neuroblastoma molecular diagnostics: report from the International Neuroblastoma Risk Group (INRG) Biology Committee.

Neuroblastoma serves as a paradigm for utilising tumour genomic data for determining patient prognosis and treatment allocation. However, before the establishment of the International Neuroblastoma Risk Group (INRG) Task Force in 2004, international consensus on markers, methodology, and data interpretation did not exist, compromising the reliability of decisive genetic markers and inhibiting translational research efforts. The objectives of the INRG Biology Committee were to identify highly prognostic genetic aberrations to be included in the new INRG risk classification schema and to develop precise definitions, decisive biomarkers, and technique standardisation. The review of the INRG database (n=8800 patients) by the INRG Task Force finally enabled the identification of the most significant neuroblastoma biomarkers. In addition, the Biology Committee compared the standard operating procedures of different cooperative groups to arrive at international consensus for methodology, nomenclature, and future directions. Consensus was reached to include MYCN status, 11q23 allelic status, and ploidy in the INRG classification system on the basis of an evidence-based review of the INRG database. Standardised operating procedures for analysing these genetic factors were adopted, and criteria for proper nomenclature were developed. Neuroblastoma treatment planning is highly dependant on tumour cell genomic features, and it is likely that a comprehensive panel of DNA-based biomarkers will be used in future risk assignment algorithms applying genome-wide techniques. Consensus on methodology and interpretation is essential for uniform INRG classification and will greatly facilitate international and cooperative clinical and translational research studies.

Management of Wilms tumors in Drash and Frasier syndromes.

BACKGROUND: Children with WT1 gene-related disorders such as Denys-Drash syndrome (DDS) and Frasier syndrome (FS) are at increased risk of Wilms tumor and end-stage renal disease. We investigated whether Wilms tumors in these patients displayed a specific phenotype or behavior and whether nephron-sparing surgery was beneficial. PROCEDURE: We retrospectively studied all patients with DDS, FS, or other WT1 mutations treated at our institutions between 1980 and 2007. RESULTS: We identified 20 patients, of whom 18 had benign or malignant tumors. Wilms tumors occurred in 15 patients, being unilateral in 10 and bilateral in 5 (20 tumors). Median age at Wilms tumor diagnosis was 9 months. No patients had metastases. According to the International Society of Pediatric Oncology Working Classification, there were 19 intermediate-risk tumors and one high-risk tumor; no tumor was anaplastic. In patients with nephropathy who underwent unilateral nephrectomy for Wilms tumor or nephron-sparing surgery for bilateral Wilms tumor, mean time to dialysis was 11 or 9 months, respectively. Other tumors included three gonadoblastomas (in two patients), one retroperitoneal soft-tissue tumor, and one transitional cell papilloma of the bladder. Two patients, both with stage I Wilms tumor, died from end-stage renal disease-related complications. The median follow-up time for the 18 survivors was 136 months (range, 17-224 months). CONCLUSION: Most Wilms tumors in children with WT1-related disorders were early-stage and intermediate-risk tumors, with a young age at diagnosis. In patients without end-stage renal disease, nephron-sparing surgery should be considered for delaying the onset of renal failure.

Chromosomal CGH identifies patients with a higher risk of relapse in neuroblastoma without MYCN amplification.

Whereas neuroblastoma (NB) with MYCN amplification presents a poor prognosis, no single marker allows to reliably predict outcome in tumours without MYCN amplification. We report here an extensive analysis of 147 NB samples at diagnosis, without MYCN amplification, by chromosomal comparative genomic hybridisation (CGH), providing a comprehensive overview of their genomic imbalances. Comparative genomic hybridisation profiles showed gains or losses of entire chromosomes (type 1) in 71 cases, whereas partial chromosome gains or losses (type 2), including gain involving 17q were observed in 68 cases. Atypical profiles were present in eight cases. A type 1 profile was observed more frequently in localised disease (P<0.0001), and in patients of less than 12 months at diagnosis (P<0.0001). A type 2 genomic profile was associated with a higher risk of relapse in the overall population (log-rank test; P<0.0001), but also in the subgroup of patients with localised disease (log-rank test, P=0.007). In multivariate analysis, the genomic profile was the strongest independent prognostic factor. In conclusion, the genomic profile is of prognostic impact in patients without MYCN amplification, making it a help in the management of low-stage NB. Further studies using higher-resolution CGH are needed to better characterise atypical genomic alterations.

Incidence and prognostic value of tumour cells detected by RT-PCR in peripheral blood stem cell collections from patients with Ewing tumour.

To retrospectively evaluate the incidence of tumour cell contamination of peripheral blood stem cell (PBSC) collections and to correlate these data with the clinical outcome after high-dose chemotherapy (HDCT) with stem cell rescue in patients with a high-risk Ewing tumour. Peripheral blood stem cell collections obtained from 171 patients were analysed. Tumour contamination was assessed by reverse transcriptase-polymerase chain reaction (RT-PCR). The files of 88 patients who underwent HDCT followed by PBSC reinfusion were reviewed in detail, and their outcome compared to the PBSC RT-PCR results. Seven of 88 PBSC collections (8%) contained tumour cells as detected by RT-PCR. Peripheral blood stem cells were collected after a median of five cycles of chemotherapy. No clinical factor predictive of tumour cell contamination of PBSC harvest could be identified. Event-free survival (EFS) and overall survival (OS) of the whole study population were 45.3 % and 51.8 % at 3 years from the date of the graft, respectively. Forty-five patients relapsed with a median time of 15 months after graft, only four of whom had tumour cell contamination of the PBSC harvest. Tumour cell contamination of PBSC collection is rare and does not seem to be associated with a significantly poorer EFS or OS in this high-risk population.

Treatment of stage 4s neuroblastoma--report of 10 years' experience of the French Society of Paediatric Oncology (SFOP).

Stage 4s neuroblastoma (NB) is usually associated with a favourable outcome, despite a large tumour burden, as spontaneous regression frequently occurs. However, in some infants rapid disease progression can be observed with severe functional impairment. Thus, for all patients the potential risks of cytotoxic therapy must be weighed against the benefits of early medical intervention. We have retrospectively reviewed the charts of 94 infants treated for stage 4s NB in centres of the French Society of Paediatric Oncology between 1990 and 2000, and describe the different first-line treatment approaches that were, successively, liver irradiation, chemotherapy using a cyclophosphamide-vincristine regimen, and chemotherapy using a carboplatin-etoposide regimen. The overall survival was 88% (+/-7.6%), with a mean follow-up of 64 months. Elevated serum neuron-specific enolase (>100 nmol ml(-1)), ferritin (>280 ng ml(-1)) and urinary dopamine levels (>2500 nmol mmol(-1) creatinine) were associated with a poor outcome, as were the genetic markers N-myc amplification and chromosome 1p deletion (P<0.0005 and P=0.0016, respectively). Patients who required medical intervention at diagnosis fared worse than those who received supportive treatment only (P<0.005). The clinical evolution observed with the different successive treatment approaches suggests that if infants do require therapy, the prompt initiation of a more intensive regimen such as carboplatin-etoposide may be more beneficial.

CGH analysis of secondary genetic changes in Ewing tumors: correlation with metastatic disease in a series of 43 cases.

The occurrence of secondary chromosome changes is frequent in Ewing tumors, in particular trisomies for chromosomes 8 and 12, and unbalanced (1;16) translocations leading to gains of 1q and losses of 16q. The prognostic value of these secondary aberrations has not been statistically demonstrated. We report here a CGH analysis of a series of 43 primary tumors corresponding to 21 localized and 22 metastatic tumors. For five of them, a sufficient amount of DNA for the CGH analysis was available from the frozen samples. For 19 samples, a preliminary step of DOP-PCR amplification of the DNA was necessary. For the last 19 tumors, DNA was obtained after DOP-PCR amplification of small amount of DNA contaminating the RNA. As a whole, the main chromosome imbalances previously described, such as trisomies for 1q, 8, and 12, were observed. It is noteworthy that the mean number of imbalances was more frequent in localized versus metastatic tumors. Gain of 1q was more frequent in metastatic than in localized tumors. Nevertheless, these two results do not reach statistical significance. Conversely, a statistically significant excess of copy number of chromosome 2 was observed in non-metastatic tumors, suggesting that this imbalance, which has never been previously reported, could be associated with more favorable tumor behavior.

[Detection of micrometastases and circulating tumour cells using molecular biology technics in solid tumours]. / Détection des micrométastases et des cellules tumorales circulantes par les techniques de biologie moléculaire dans les tumeurs solides.

The extension of a cancer is a major prognostic factor which determines the therapeutic strategy. The occurrence of metastatic relapses in patients with initially localized tumours, despite a good local control, gives evidence for the possibility of spreading of occult tumour cells. The recent improvements of immunohistochemistry and molecular biology methods enable to detect tumour cells in various sites such as lymph nodes, bone marrow and blood with a considerably increased sensitivity as compared to conventional approaches. The markers used to detect tumour cells by PCR or RT-PCR can be either "tissue-specific" or "tumour specific". The drawback of the first group of markers is linked to the observation that tissue-specificity is frequently a relative concept leading to a high rate of false positives. Tumour-specific markers include gene fusions observed in various sarcomas, point mutations and presence of viral genomes in tumour cells. They are available and can be easily monitored in only a limited set of cancers. This review focuses on the molecular biology approaches which are used to detect occult tumour cells and on their clinical applications. The large number of studies which have been published in that field show that such a detection can be performed in a variety of target sites. However, results of studies performed on larger series of patients together with a better standardization of technics are necessary before they can be used for individual staging of patients.

Autologous haematopoietic stem cell transplantation for paediatric solid tumours.

High-dose chemotherapy followed by autologous haematopoietic rescue is widely used in the treatment of patients with paediatric malignancies. It is now well established as a major component for the treatment of children with metastatic neuroblastoma over the age of one at diagnosis. Its place for other tumours, such as metastatic Ewing and rhabdomyosarcoma, needs to be better established. In the future, high-dose chemotherapy may replace cranio-spinal irradiation in the treatment of medulloblastoma in young children and represent a major tool for retrieval therapy in relapsing Wilm's and retinoblastoma. More co-operative studies are needed in order to clarify the population of patients who may most benefit from this approach and to determine the optimal chemotherapy regimen needed for each disease.

Clinical relevance of loss heterozygosity of the short arm of chromosome 1 in neuroblastoma: a single-institution study.

Neuroblastoma is characterized by a wide variability of its clinical course, and considerable effort has been made to identify factors determining outcome in this disease. In a series of 82 patients from a single institution, we have investigated the prognostic impact of multiple clinical, biological and genetic parameters. Univariate testing showed that advanced stage of disease, abdominal localization of the primary tumor, elevated urinary dopamine levels, N-myc amplification (NMA) and loss of heterozygosity of chromosome lp (LOH lp) were related to a poor outcome. Most of these parameters were strong indicators of treatment failure in children younger than 12 months of age but none of them, apart from stage, had a significant prognostic impact in patients older than 12 months at diagnosis. Interestingly, the shorter survival time associated with the presence of lp deletions or NMA appears to be more strongly linked to a poorer outcome after relapse or progression than to a shorter progression-free interval. Although different types of LOH lp have been described in neuroblastoma and may be associated with different biological features, as suggested by a different pattern of catecholamine secretion, tumors with LOH lp present an aggressive clinical behavior, regardless of the type of LOH lp. In this study, LOH lp is an indicator of poor prognosis and identifies a larger population at risk than NMA alone.

N-MYC amplification, loss of heterozygosity on the short arm of chromosome 1 and DNA ploidy in retinoblastoma.

Recurrent genetic alterations different from the alteration of the RB1 gene on chromosome 13q14 have been described in retinoblastoma, including structural alterations on the short arm of chromosome 1 and amplification of the N-MYC oncogene. These two genetic alterations are major prognostic factors in neuroblastoma, another embryonic neuro-ectodermal tumour. In order to assess the frequency of these alterations and their possible association with clinical parameters in retinoblastoma, we studied a series of 46 retinoblastoma tumour samples. Ploidy was assessed by flow cytometry, N-MYC copy number was evaluated by a spot-blot procedure using the pNb-1 probe and loss of heterozygosity was investigated by PCR analysis at mini- and microsatellites located on the short arm of chromosome 1. Most tumours were in the diploid or near diploid range; only one case exhibited tetraploidy. N-MYC amplification was observed in only one of the 45 tumours. Loss of heterozygosity on the short arm of chromosome 1 was observed in 9/43 tumours (21%); in particular, its incidence was higher in metastatic than in localised disease (P < 0.05). We suggest that alterations of one or several genes on chromosome 1p might play a role in the oncogenesis or progression of retinoblastoma. Analysis of the long term follow-up of these and additional patients should determine the prognostic value of this parameter.