Evolving significance of prognostic markers associated with treatment improvement in patients with stage 4 neuroblastoma

17q Gain in Neuroblastoma: A Review of Clinical and Biological Implications

Neuroblastoma (NB) is the most frequent extracranial solid childhood tumor. Despite advances in the understanding and treatment of this disease, the prognosis in cases of high-risk NB is still poor. 17q gain has been shown to be the most frequent genomic alteration in NB. However, the significance of this remains unclear because of its high frequency and association with other genetic modifications, particularly segmental chromosomal aberrations, 1p and 11q deletions, and MYCN amplification, all of which are also associated with a poor clinical prognosis. This work reviewed the evidence on the clinical and biological significance of 17q gain. It strongly supports the significance of 17q gain in the development of NB and its importance as a clinically relevant marker. However, it is crucial to distinguish between whole and partial chromosome 17q gains. The most important breakpoints appear to be at 17q12 and 17q21. The former distinguishes between whole and partial chromosome 17q gain; the latter is a site of IGF2BP1 and NME1 genes that appear to be the main oncogenes responsible for the functional effects of 17q gain.

The prognostic strength of serum LDH and serum ferritin in children with neuroblastoma: A report from the International Neuroblastoma Risk Group (INRG) project

PURPOSE

Age, MYCN status, stage, and histology have been used as neuroblastoma (NB) risk factors for decades. Serum lactate dehydrogenase (LDH) and serum ferritin are reproducible, easily obtained, and prognostic, though never used in risk stratification, except one German trial. We analyzed the prognostic strength of LDH and ferritin, overall, within high-risk NB, and by era, using the International Neuroblastoma Risk Group Data Commons.

PATIENTS AND METHODS

Children with NB (1990-2016) were categorized into LDH (n = 8867) and ferritin (n = 8575) risk groups using EFS. Cox models compared the prognostic strength of LDH and ferritin to age, MYCN status, and INSS stage.

RESULTS

Higher LDH conferred worse EFS, overall (5-year EFS) (100-899 IU/L: 76 ± 0.6%; 0-99 or 900-1399 IU/L: 60 ± 1.2%; ≥1400 IU/L: 36 ± 1.2%; P < .0001), and in high-risk NB post-2009 (3-year EFS) (117-381 IU/L: 67 ± 8.9%; 382-1334 IU/L: 58 ± 4.4%; 0-116 or ≥1335 IU/L: 46 ± 3.9%; P = .003). Higher ferritin conferred worse EFS, overall (5-year EFS) (1-29 ng/mL: 87 ± 0.9%; 0 or 30-89 ng/mL: 74 ± 0.8%; ≥90 ng/mL: 48 ± 0.9%; P < .0001), and in high-risk NB post-2009 (3-year EFS) (1-53 ng/mL: 71 ± 9.3%; 0 or 54-354 ng/mL: 55 ± 4.7%; ≥355 ng/mL: 34 ± 6.1%; P = .0008). In multivariable analyses adjusting for age, MYCN, and stage, LDH and ferritin maintained independent prognostic ability (P < .0001; adjusted HRs (95% CI): 1.7 (1.5-1.9), 2.3 (2.0-2.7), respectively).

CONCLUSIONS

LDH and ferritin are strongly prognostic in NB, overall and within high-risk NB patients treated post-2009 with modern therapy. LDH and ferritin show promise for (a) identifying ultra-high-risk; (b) refining risk stratification; and (c) clinical utility in low-/middle-income countries. Routine collection of LDH and ferritin should be reinitiated for evolving NB risk stratification.

Comprehensive evaluation of context dependence of the prognostic impact of MYCN amplification in neuroblastoma: A report from the International Neuroblastoma Risk Group (INRG) project

BACKGROUND

MYCN amplification (MYCN-A) is an established adverse prognostic factor in neuroblastoma. The extent to which the prognostic impact of MYCN-A depends on other factors has not been fully characterized.

PATIENTS AND METHODS

Using the International Neuroblastoma Risk Group database, we constructed Cox models of overall survival (OS) to obtain hazard ratios of the effect of MYCN-A within subgroups defined by other prognostic factors. Cox models assessed the degree to which the prognostic impact of MYCN-A was modulated by each other covariate. We used absolute hazard ratio (HR) differences to construct classification trees to identify subgroups with greatest differential prognostic effect of MYCN-A.

RESULTS

In a cohort of 6223 patients with known MYCN status, the OS hazard ratio associated with MYCN-A was 6.3 (95% confidence interval 5.7-7.0, P < .001). Age at diagnosis conferred the largest HR absolute difference for MYCN-A between subgroups (HR absolute difference 16.6; HRs for MYCN-A of 19.6 for <18 months, 3.0 for ≥18 months). MYCN-A remained significantly prognostic of OS after controlling for other factors, abrogating their prognostic strength. Patients whose outcome was most impacted by MYCN status were those who were <18 months, had high mitosis karrhyohexis index (MKI) and low ferritin.

CONCLUSION

The prognostic strength of MYCN-A varies depending on which patient subgroup defined by other neuroblastoma risk factors is examined, with greatest strength in patients with otherwise favorable features. MYCN-A has little effect within some subgroups, aiding clinical decision-making if MYCN status cannot be assessed. Subgroups where MYCN-A has large effect may be prioritized for agents targeting Myc family proteins.

Clinico-epidemiology of neuroblastoma in north east Egypt: A 5-year multicenter study

Neuroblastoma, an embryonal malignancy of the sympathetic nervous system, is the most frequent extracranial solid tumor The clinico-epidemiological features of neuroblastoma in infants and children were investigated between January 2005 and January 2010 at the Pediatric Oncology units of Mansoura, Zagazig, and Tanta University Children's Hospitals (Egypt). Of 142 cases of neuroblastoma, 10 were omitted from the study due to defective data. The median age of the patients was 30 months, with 75.8% aged ≥1 year and 24.2% aged <1 year at time of diagnosis. The male-to-female ratio was 1.06. Suprarenal glands were the most common primary tumor site (72.7%). The majority of the patients (76.7%) had stage IV disease. Favorable pathology was observed in 43.8% of patients, while 56.2% exhibited unfavorable pathology. The estimated survival rate of patients was 30.7±10.0%, and mean survival time was 24.2±5.2 months. The rate of mortality was 28.6% for patients aged <1 year, and 81.8% for those aged ≥1 year (P=0.005). For patients with favorable pathology, the rate of mortality was significantly lower (28.6%) compared with that of patients with unfavorable pathology (77.8%; P=0.049). Although the association between outcome and each of the primary tumor sites, children's oncology group risk and gender was statistically insignificant, a large effect size was identified between outcome and primary tumor site, as well as children's oncology group risk and a medium effect size was identified between outcome and gender. Additionally, an age of ≥1 year was associated with unfavorable pathology (P=0.024), stage IV disease (P=0.026) and a suprarenal primary tumor site (P=0.001).

Cold atmospheric plasma for the ablative treatment of neuroblastoma

BACKGROUND

Recent breakthroughs have allowed for production of plasma at room temperature. Cold atmospheric plasma (CAP) may offer the capability of delivering reactive oxygen species directly into tissues, representing a novel modality for targeted cancer therapy. We studied helium-based CAP's effect on neuroblastoma, both in-vitro and in an in-vivo murine model.

METHODS

Mouse neuroblastoma cultures were treated with CAP for 0, 30, 60, and 120 s and assayed for apoptotic and metabolic activity immediately and at 24 and 48 h post-treatment. Five-millimeter tumors were ablated with a single transdermal CAP treatment, and tumor volume and mouse survival were measured.

RESULTS

CAP decreased metabolic activity, induced apoptosis, and reduced viability of cancer cells in proportion to both duration of exposure and time post-treatment. In-vivo, a single treatment ablated tumors and eventual tumor growth was decelerated. Furthermore, survival nearly doubled, with median survival of 15 vs. 28 days (p<0.001).

CONCLUSIONS

Our findings demonstrate the sensitivity of neuroblastoma to CAP treatment, both in-vitro and in an in-vivo mouse model of established tumor. While further investigation is necessary to establish the mechanism and optimize the treatment protocol, these initial observations establish cold atmospheric plasma as a potentially useful ablative therapy in neuroblastoma.

Local control of the primary tumour in metastatic neuroblastoma

The previous studies have stressed on the importance of loco-regional control in the management of high-risk neuroblastoma. We searched the Surveillance, Epidemiology and End-Results (SEER) database for patients older than 2years with metastatic neuroblastoma who were diagnosed from 1998 to 2005. We identified 291 patients (mean age, 4.35years). The 5-year survival estimate was 53.2%+/-6.4% for patients who had complete resection of their primary tumours (n=116) and 35.7%+/-4.7% for patients who did not have complete resection (p=0.003). External-beam radiotherapy did not affect survival (p=0.79); this finding has to be taken with caution due to the study limitations.

Differential expression of genes mapping to recurrently abnormal chromosomal regions characterize neuroblastic tumours with distinct ploidy status

Background

Neuroblastic tumours (NBTs) represent a heterogeneous spectrum of neoplastic diseases associated with multiple genetic alterations. Structural and numerical chromosomal changes are frequent and are predictive parameters of NBTs outcome. We performed a comparative analysis of the biological entities constituted by NBTs with different ploidy status.

Methods

Gene expression profiling of 49 diagnostic primary NBTs with ploidy data was performed using oligonucleotide microarray. Further analyses using Quantitative Real-Time Polymerase Chain Reaction (Q-PCR); array-Comparative Genomic Hybridization (aCGH); and Fluorescent in situ Hybridization (FISH) were performed to investigate the correlation between aneuploidy, chromosomal changes and gene expression profiles.

Results

Gene expression profiling of 49 primary near-triploid and near-diploid/tetraploid NBTs revealed distinct expression profiles associated with each NBT subgroup. A statistically significant portion of genes mapped to 1p36 (P = 0.01) and 17p13-q21 (P < 0.0001), described as recurrently altered in NBTs. Over 90% of these genes showed higher expression in near-triploid NBTs and the majority are involved in cell differentiation pathways. Specific chromosomal abnormalities observed in NBTs, 1p loss, 17q and whole chromosome 17 gains, were reflected in the gene expression profiles. Comparison between gene copy number and expression levels suggests that differential expression might be only partly dependent on gene copy number. Intratumoural clonal heterogeneity was observed in all NBTs, with marked interclonal variability in near-diploid/tetraploid tumours.

Conclusion

NBTs with different cellular DNA content display distinct transcriptional profiles with a significant portion of differentially expressed genes mapping to specific chromosomal regions known to be associated with outcome. Furthermore, our results demonstrate that these specific genetic abnormalities are highly heterogeneous in all NBTs, and suggest that NBTs with different ploidy status may result from different mechanisms of aneuploidy driving tumourigenesis.

Long-term outcomes in patients with stage IV neuroblastoma

AIM OF STUDY

Long-term outcome studies in survivors with stage IV neuroblastoma (NB) are sparse. This review evaluates late complications and long-term outcomes in stage IV NB survivors.

METHODS

A retrospective review of stage IV NB survivors was performed to analyze outcomes, including long-term morbidity, recurrence, and survival.

MAIN RESULTS

Of 153 patients with stage IV NB, 52 (34%) survived (male-female, 26:26). Age at diagnosis was 29.1 +/- 31.7 months in survivors. Eighteen were 1 year or younger and 34 were older than 1 year compared with 10 nonsurvivors 1 year or younger and 91 older than 1 year (P = .0003, Fisher's Exact test). Primary tumor sites were adrenal (35), retroperitoneal (11), mediastinal (3), pelvic (2), and no primary with tumor metastases identified (1). Ten survivors had favorable and 16 had unfavorable histology compared with 1 favorable and 18 unfavorable in nonsurvivors (P = .01). Four survivors had MYCN amplification (> or = 10 copies) and 2 deletions of 1p and 11q. Sites of metastasis in survivors and nonsurvivors were similar. Treatment in survivors included surgery in 51 (75% [39/51] complete tumor resection [CTR]); chemotherapy, 50; radiation, 17; stem cell transplantation, 20; and bone marrow transplant, 1. In nonsurvivors, 13 (25%) of 53 (P < < .0001) had CTR, 18 stem cell transplantation, and 12 bone marrow transplant. Six patients had tumor recurrence but survived (mean, 9.3 +/- 8.3 years; range, 6 months-24 years). Recurrence was local (1), distant (2), and both (3) and was treated by resection, chemotherapy, and radiation. The mean age of survivors was 12.4 +/- 8.3 years (range, 2-34 years). In all stage IV cases, event-free survival was 30% and overall survival was 34%. Long-term complications occurred in 23 (44%) survivors, including endocrine disturbances (7), orthopedic (5), cataracts (2), adhesive bowel obstruction (2), hypertension (1), bronchiolitis (1), blindness (1), peripheral neuropathy (1), nonfunctioning kidney (1), cholelithiasis (1), and thyroid nodule (1).

CONCLUSION

Only 34% of patients with stage IV NB survived despite aggressive multimodal therapy. Age of younger than 1 year, favorable pathology, CTR, and no recurrence were the only statistically significant factors that favored survival. Forty-four percent of survivors experienced late morbidity, and tumor recurred in 6 (11.5%) of 52. Patients should be monitored for tumor recurrence and long-term sequelae. New methods of treatment are required to achieve better outcomes.

Region-specific detection of neuroblastoma loss of heterozygosity at multiple loci simultaneously using a SNP-based tag-array platform

Many cancers are characterized by chromosomal aberrations that may be predictive of disease outcome. Human neuroblastomas are characterized by somatically acquired copy number changes, including loss of heterozygosity (LOH) at multiple chromosomal loci, and these aberrations are strongly associated with clinical phenotype including patient outcome. We developed a method to assess region-specific LOH by genotyping multiple SNPs simultaneously in DNA from tumor tissues. We identified informative SNPs at an average 293-kb density across nine regions of recurrent LOH in human neuroblastomas. We also identified SNPs in two copy number neutral regions, as well as two regions of copy number gain. SNPs were PCR-amplified in 12-plex reactions and used in solution-phase single-nucleotide extension incorporating tagged dideoxynucleotides. Each extension primer had 5' complementarity to one of 2000 oligonucleotides on a commercially available tag-array platform allowing for solid-phase sorting and identification of individual SNPs. This approach allowed for simultaneous detection of multiple regions of LOH in six human neuroblastoma-derived cell lines, and, more importantly, 14 human neuroblastoma primary tumors. Concordance with conventional genotyping was nearly absolute. Detection of LOH in this assay may not require comparison to matched normal DNAs because of the redundancy of informative SNPs in each region. The customized tag-array system for LOH detection described here is rapid, results in parallel assessment of multiple genomic alterations, and may speed identification of and/or assaying prognostically relevant DNA copy number alterations in many human cancers.

Identification of MYCN Gene Amplification in Neuroblastoma Using Chromogenic In Situ Hybridization (CISH)

Chromogenic in situ hybridization (CISH) is a recently developed technique, which utilizes the general principles of in situ hybridization and a detection system similar to immunohistochemistry. To assess the utility of CISH for analysis of MYCN gene amplification, we compared this assay with established diagnostic assays such as Southern blot analysis (SB) and fluorescent in situ hybridization (FISH). CISH was performed on 67 cases of neuroblastoma using tissue microarray (65 cases) and whole tissue sections (2 cases). Unequivocal, high-level amplification (> or =10 gene copies per tumor nucleus) was identified in 19 of 67 (28.4%) tumors. Two (3%) tumors showed low-level amplification (6-9 gene copies per tumor nucleus). No amplification was seen in 46 of 67 (68.6%) tumors. SB data were available in 44 tumors. Forty-one of the 44 tumors (93%) showed concordant results between CISH and SB. Three tumors showed MYCN amplification by CISH but no amplification by SB, most likely due to dilution effect of nonneoplastic tissue in the test samples. Two of these three tumors also showed MYCN amplification by FISH, and the third tumor was not analyzed by FISH. FISH data were available in total of 30 tumors. All 30 tumors showed concordant results between CISH and FISH for classifying a tumor as MYCN amplified or not amplified. We conclude that CISH is an accurate method for determining MYCN gene amplification, with added advantages that make it a more practically useful method.

Profiling of nuclear extract proteins from human neuroblastoma cell lines: the search for fingerprints

PURPOSE

Neuroblastoma (NB) commonly presents with advanced disease at diagnosis and is associated with poor survival. If identified early, however, survival is improved suggesting a benefit of early detection. The authors have used proteomics technology in an attempt to identify novel markers that permit early detection of NB and characterize its molecular makeup.

METHODS

Three different human NB cell lines SK-N-AS, SK-N-DZ, and SK-N-FI were subjected to series of biochemical fractionation steps to extract nuclear proteins. These proteins were analyzed for differential expression by 2-dimensional polyacrylamide gel electrophoresis. Polypeptides of interest were subsequently identified by liquid chromatography-linked tandem mass spectrometry.

RESULTS

Multiple proteins were identified in these human NB cell lines including SET (a ubiquitous nuclear protein), stathmin (a cytosolic signal transduction protein), and grp94 (a heat shock protein). SET is a putative oncogene associated with the chromosomal translocation (6;9) leading to acute undifferentiated leukemia. Stathmin is an oncogene found in greater abundance in leukemic cells compared to nonleukemic cells. A total of 94-kDa glucose-regulated protein has been shown to be protective in human breast cancer cells in vitro and related with the occurrence, differentiation, and progression of human lung cancer. The first protein has not been previously associated with NB.

CONCLUSIONS

The identification of these 3 previously unrecognized cancer-related potential biomarkers in human NB cell lines may prove useful in developing diagnostic tests. The proteomic methodology of 2-dimensional polyacrylamide gel electrophoresis/mass spectrometry also provides an improved opportunity to understand the natural history of NB and develop novel chemotherapeutic agents for this prevalent childhood malignancy with a dismal outcome.

Comprehensive analysis of the 9p21 region in neuroblastoma suggests a role for genes mapping to 9p21-23 in the biology of favourable stage 4 tumours

Chromosome 9p21 is frequently deleted in many cancers. Previous reports have indicated that 9p21 LOH is an uncommon finding in neuroblastoma (NB), a tumour of childhood. We have performed an extensive analysis of 9p21 and genes located in this region (cyclin-dependent kinase inhibitor 2A – CDKN2A/p16^INK4a, CDKN2A/p14^ARF, CDKN2B/p15^INK4b, MTAP, interferon α and β cluster). LOH was detected in 16.4% of 177 NB. The SRO was identified between markers D9S1751 and D9S254, at 9p21–23, a region telomeric to the CDKN2A and MTAP genes. A significantly better overall and progression-free survival was detected in stage 4 patients displaying 9p21–23 LOH. Hemizygous deletion of the region harbouring the CDKN2A and CDKN2B loci was identified in two tumours by means of fluorescent in situ hybridisation and MTAP was present by immunostaining in all but one tumour analysed. The transcriptional profile of tumours with 9p21–23 LOH was compared to that of NB displaying normal 9p21–23 status by means of oligonucleotide microarrays. Four of the 363 probe sets downregulated in tumours with 9p21–23 LOH were encoded by genes mapping to 9p22–24. The only well-characterised transcript among them was nuclear factor I-B3. Our results suggest a role for genes located telomeric of 9p21 in good risk NB.

Positional gene expression analysis identifies 12q overexpression and amplification in a subset of neuroblastomas

Neuroblastoma is a heterogeneous disease with variable clinical behaviors. Unique molecular features are associated with clinically relevant subgroups. We performed a comprehensive microarray gene expression analysis of 95 neuroblastomas in an effort to define clinically important molecular subtypes. A subset of tumors overexpressed several contiguous genes located at 12q13 approximately q15 and were studied further. By microarray, 5 of 95 neuroblastomas had overexpression of genes mapped to 12q13.1 approximately q15, suggesting an amplification event in this region. Positional expression mapping identified the narrowest region of overlap containing 21 genes, with 11 genes overexpressed in all five cases. Fluorescence in situ hybridization demonstrated 3 neuroblastomas with more than a 10-fold increase in 12q gene copies and 9 with 3- to 5-fold increases. Amplification and overexpression of genes at 12q13 approximately q15 were observed in a small subset of neuroblastomas. Although amplification of 12q has been previously reported in neuroblastoma cell lines, this is the first demonstration in tumor samples, and it defines a distinct subset that has not been described previously. The expressed genes mapped closely to the complex amplicon reported in sarcomas, and they identify critical genes and pathways affected by 12q gene amplification.

[Prognosis of neuroblastoma in childhood. Methods of assessment and clinical use]

Neuroblastoma and its benign counterpart, ganglioneuroma, are pediatric neuroblastic tumors arising in the sympathetic nervous system from neural-crest cells. Neuroblastoma, the most common extra-cranial solid tumour during childhood, is unique for its broad spectrum of clinical virulence from spontaneous remission to rapid and fatal progression despite intensive multimodality therapy. To a large extent, outcome could be predicted by the stage of disease and the age at diagnosis. However, a number of molecular events in neuroblastoma tumors, accounting for the variability of outcome and response to therapy, have been identified over the past decades. Among these, MYCN amplification is the most relevant prognostic factor and was the first genetic marker, in paediatric oncology, to be included in clinical strategies as a guide for therapeutic decision. This has allowed the most suitable intensity of therapy to be delivered according to a risk-stratified strategy, from observation to megadose chemotherapy with stem cell transplantation. Recent advances in understanding the biology and genetics of neuroblastoma will ultimately allow to select poor-risk patients for appropriate future biologically based therapies.

Molecular Detection of Dopamine Decarboxylase Expression by Means of Reverse Transcriptase and Polymerase Chain Reaction in Bone Marrow and Peripheral Blood

A highly sensitive molecular method was used to evaluate the presence of dopamine decarboxylase (DDC) mRNA in the bone marrow and peripheral blood of patients with neuroblastoma (NB). DDC, like tyrosine hydroxylase (TH), is an enzyme involved in the catecholamine synthesis pathway and has recently been proposed as a specific marker of NB among pediatric malignancies. DDC transcript was detected in five of five NB cell lines, 10 of 10 NB primary tumors, 17 of 18 (94%) bone marrow samples, and 12 of 18 (66%) blood samples drawn at diagnosis in 18 patients affected by disseminated NB. In contrast, no PCR signal was found in 20 bone marrow samples obtained from patients with other malignancies or in eight of nine marrow and blood samples drawn from patients with localized NB (two stage 2 and seven stage 3). In addition, all marrow and blood samples obtained from NB patients at relapse revealed DDC mRNA. Furthermore, the percentage of DDC-positive samples was lower among the samples drawn from these patients during treatment. By comparison with conventional methods for disease evaluation, DDC transcript research can increase the sensitivity of NB cell detection in marrow and blood samples at diagnosis and during the treatment and follow-up of NB patients. These results suggest that finding DDC mRNA in NB patients could be a potential marker for minimal residual disease study.

Long-term results of high-dose chemotherapy and autologous stem cell rescue for high-risk neuroblastoma patients: a report of the Spanish working party for BMT in children (Getmon)

The authors retrospectively analyzed the long-term outcome of 67 patients over 1 year of age at diagnosis with high-risk neuroblastoma (stage 4 or stage 3 with N-myc amplification) who were treated with megatherapy and stem cell rescue from 1984 to 1998. Median age at transplant was 4 years (range 1.6-15 years). The source of cells was peripheral stem cells in 29 and bone marrow in 38 patients. In 12 patients, an in vitro purging of bone marrow harvest was performed. Most patients were conditioned with melphalan, BCNU, and VM-26. After transplant 19 patients received complementary treatment with IL-2 (16) or 13-cis-retinoic acid (3). Six patients (8%) died from transplant-related toxicity and 39 from disease progression. Three patients were alive with active disease at the time of analysis. Nineteen patients are alive and disease-free at a median follow-up of 104 months. Five-year event-free survival is 0.30. Survival of patients who received a purged graft was not significantly better than the rest. Post-transplant complementary treatment significantly improved overall and event-free survival (p = .01 and p = .04, respectively).

Long-term follow-up status of patients with neuroblastoma after undergoing either aggressive surgery or chemotherapy--a single institutional study

BACKGROUND/PURPOSE

Before adopting a national protocol of aggressive chemotherapy for patients with advanced neuroblastoma in 1985, the treatment strategies in use varied considerably among the institutions in Japan. An aggressive surgical resection was the treatment of choice at the authors' institution before 1985. To better understand treatment-related complications, the authors retrospectively investigated the long-term morbidity of patients who had reached adulthood.

METHODS

Sixteen patients with neuroblastoma currently 18 years of age or older were incorporated into the study. All were non-mass screening cases, and 13 of the patients had undergone aggressive surgery, whereas the remaining 3 cases had received aggressive chemotherapy.

RESULTS

In the 13 patients who had undergone aggressive surgical treatment, a unilateral atrophy of the kidney was noted in 2 cases of adrenal and retroperitoneal neuroblastomas, respectively. Dry ejaculation was noted in one case of a giant presacral neuroblastoma. A maldevelopment of the unilateral lower extremity was also noted in another case with a presacral tumor, which had been resected by abdominal and sacral approaches. In the 3 patients who had undergone aggressive chemotherapy, severe hearing loss occurred in 2 cases. However, social adaptation was well preserved in all 16 cases.

CONCLUSIONS

Treatment-specific complications were found in both the aggressive surgery and chemotherapy groups. These results should, therefore, be taken into account when developing future treatment protocols.

Neuroblastoma: biology and molecular and chromosomal pathology

Neuroblastoma is the most frequently occurring solid tumour in children, with an incidence of 1.3 cases per 100000 children aged 0-14 years. Despite many advances during the past three decades, neuroblastoma has remained an enigmatic challenge to clinical and basic scientists. 20 years ago, the MYCN gene was found to be amplified in neuroblastomas, and research since then has focused on the search for other genetic markers. It has emerged that neuroblastoma cells, like cells of many other tumour types, often suffer from extensive, non-random genetic damage at multiple genetic loci. Elucidation of the exact molecular make-up of neuroblastomas will enable researchers to analyse how much specific markers, alone or in combination, can help to stratify disease in prospective studies; at present, stratification is based on age, stage, MYCN, and Shimada pathology. Neuroblastoma may be one of the first examples of the use of genetic tumour markers as a tool for defining tumour behaviour and to aid clinical staging.

der(11)t(11;17): a distinct cytogenetic pathway of advanced stage neuroblastoma (NBL) - detected by spectral karyotyping (SKY)

Conventional cytogenetic, molecular cytogenic and genetic methods disclosed a broad spectrum of genetic abnormalities leading to gain and loss of chromosomal segments in advanced stage neuroblastoma (NBL). Specific correlation between the genetic findings could delineate distinct genetic pathways, of which the biology and prognostic significance is as yet undetermined. Using spectral karyotyping (SKY) and fluorescence in situ hybridization (FISH) on metaphases from 16 patients with advanced stage NBL, it was possible to explore the whole spectrum of rearrangement within complex karyotypes and to detect hidden recurrent translocations. All translocations were unbalanced. The most prevalent recurrent unbalanced translocations resulted in 17q gain in 12 patients (75%), 11q loss in nine patients (56%), and 1p deletion/imbalance in eight patients (50%). The most frequent recurrent translocation was der(11)t(11;17) in six patients. Three cytogenetic pathways could be delineated. The first, with six patients, was characterized by the unbalanced translocation der(11)t(11;17), detected only by SKY, resulting in the concomitant 17q gain and 11q loss. No MYCN amplification or 1p deletion (except one patient with 1p imbalance) were found, while 3p deletion, and complex karyotypes were common. The second subgroup, with four patients, had 17q gain and 1p deletion, and in two patients 11q loss, that was apparent only by FISH. 1p deletion occurred through der(1)t(1;17) or del(1p). The third subgroup of four patients was characterized by MYCN amplification with 17q gain and 1p deletion, very rarely with 11q loss (one patient) through a translocation with a non-17q partner. The SKY subclassifications were in accordance with the findings reported by molecular genetic techniques, and may indicate that distinct oncogenes and suppressor genes are involved in the der(11)t(11;17) pathway of advanced stage NBL.

Evolving significance of prognostic markers associated with new treatment strategies in neuroblastoma

The striking differences in the natural history of clinical subgroups of neuroblastoma (NB), and the evolving therapeutic approaches for each, makes it imperative for prognostic markers to be reevaluated within individual clinical categories. At least one third of NB cases present without distant metastasis and cytotoxic therapy does not alter the natural history. We carried out a retrospective analysis of archived tumor samples. Fifty-seven of these patients had local-regional (LR) NB and were managed conservatively, initially treated with surgery alone. Among the biologic and clinical features analyzed including age, stage, histology, ploidy, MYCN, and 1p36, 1p22, 11q, 14q, 9p and 19q loss of heterozygosity (LOH) in multivariate analysis, diploidy was one of the most significant factors associated with progression-free survival and stage 4 progression. Clonal ploidy heterogeneity was common in LR NB. A predominant near-triploid clonal population was found in most cases of non-progressing LR NB tumors whereas progressing LR NB cases had a predominant diploid clone. We also reviewed the prognostic factors among 84 stage 4 NB cases treated with the N5, N6 or N7 protocols at MSKCC from 1987 to 1999. Traditional markers such as lactate dehydrogenase (LDH), ferritin, age and MYCN status were not prognostic in the univariate analysis. 11q23 and 1p22 LOH were correlated with better survival. These results highlight the evolving significance of prognostic analysis in homogeneous clinical groups undergoing similar treatments. To further characterize the gene expression profile between local-regional and metastatic NB, we carried out Microarray analysis of 41 NB tumors and 12 NB cell lines, using the Affymetrix Genechip Human Genome U95 Set. Distinct gene expression patterns between metastatic and non-metastatic NB tumors have been identified. Validation of these results and further mechanistic studies may shed new light on the biology of metastasis in human NB.