Loss of heterozygosity for chromosome 14q in neuroblastoma

BACKGROUND: Neuroblastoma is a genetically heterogeneous disease, with subsets of tumors demonstrating rearrangements of several genomic regions. Preliminary studies from several groups have identified loss of heterozygosity (LOH) for the long arm of chromosome 14 (14q) in 20-25% of primary neuroblastomas. PROCEDURE: To determine precisely the frequency and extent of 14q deletions, we performed LOH analysis for a large series of primary neuroblastomas using a panel of 11 highly polymorphic markers. RESULTS: LOH was detected in 83 of 372 tumors (22%). Although the majority of tumors with allelic loss demonstrated allelic loss for all informative markers, 13 cases showed LOH for only a portion of 14q. A single consensus region of deletion, which was shared by all tumors with 14q LOH, was defined within 14q23-q32 between D14S588 and the 14q telomere. Allelic loss for 14q was strongly correlated with the presence of 11q LOH (P < 0.001 ) and inversely correlated with MYCN amplification (P= 0.04). CONCLUSIONS: LOH for 14q was evident in all clinical risk groups, indicating that this abnormality may be a universal feature of neuroblastoma tumor development. These findings suggest that a tumor suppressor gene involved in the initiation or progression of neuroblastoma is located within distal 14q.     

Comprehensive analysis of chromosome 1p deletions in neuroblastoma

BACKGROUND: Chromosome 1p deletions are common in advanced neuroblastomas, but the biological and clinical implications of this clonal rearrangement remain controversial. Previous studies of chromosome 1p loss of heterozygosity (LOH) have been limited by analyses of relatively small number of tumors derived from heterogeneously assessed and treated patient populations. Therefore, a strictly representative cohort of 288 Children's Cancer Group neuroblastoma patients treated on the most recent phase III therapeutic trials was identified. PROCEDURE: Primary tumors from these patients were analyzed for LOH at precisely mapped and highly informative 1p polymorphic loci located from 1p32 to 1p36.3 by multiplex PCR. RESULTS: Ninety-three primary tumor specimens (32%) had LOH at multiple 1p36 marker loci. All 1p deletions overlapped the previously determined smallest region of overlap (SRO). One tumor had a small terminal deletion completely within 1p36.3, allowing for further refinement of the 1p36 SRO. We found no evidence to support an additional, nonoverlapping region of LOH within 1p32-36. We confirmed the strong correlation of 1p36 LOH with MYCN amplification (P < 0.001), advanced disease stage (P < 0.001), and decreased both 3-year event-free survival and overall survival probabilities (P< 0.001). When stratified for MYCN amplification status or entered into a multivariate analysis, 1p36 LOH remained predictive for decreased event-free survival, but not overall survival probability. CONCLUSIONS: These data support the hypothesis that inactivation of a tumor suppressor gene within 1p36.3 is associated with an increased risk for disease relapse.     

Analysis of genomic imprinting at 1p35-36 in neuroblastoma

BACKGROUND: Deletion of the distal short arm of chromosome 1 occurs in 25-35% of primary neuroblastomas, and a putative tumor suppressor gene has been mapped to a consensus region of deletion at 1p36.2-36.3. Indirect evidence suggests the presence of an imprinted neuroblastoma suppressor gene within this region, as well as an additional nonimprinted, proximal suppressor gene, inactivation of which correlates with MYCN amplification. PROCEDURE: To test this hypothesis, we performed 1p loss of heterozygosity (LOH) studies on a series of neuroblastomas for which parental DNA had been collected. PCR-formatted polymorphic markers were used to determine the size of the 1p deletion and the parental origin of the deleted 1p homologue. RESULTS: Twenty-six neuroblastomas with 1p LOH were evaluated. Twenty-four had MYCN amplification, and of these, 15 demonstrated loss of the paternally inherited 1p. Two neuroblastomas with a single copy of MYCN were evaluated and both had deletion of the paternally inherited 1p, with one case exhibiting a small terminal deletion. In addition, we have reviewed 49 previously reported neuroblastomas where 1p LOH data and the parental origin of the deleted lp homologue were available. CONCLUSIONS: Analyzed together, these 75 neuroblastomas demonstrate random deletion of parental 1p homologues (P = 0.30). Further, tumors with smaller deletions (breakpoints distal to D1S201 or D1S7) showed a random loss of the parental 1p homologues (P = 0.59), contrary to the expected preferential maternal 1p deletion if an imprinted suppressor gene mapped to this region. However, 19 tumors with 1p LOH and single copy MYCN had deletion of the maternal 1p homologue preferentially (P = 0.02), which does not exclude the possibility that loss of an imprinted suppressor gene plays a role in this subset.     

Deletion of 11q23 is a frequent event in the evolution of MYCN single-copy high-risk neuroblastomas

BACKGROUND: Deletions of the long arm of chromosome 11 are frequently identified in human neuroblastomas. PROCEDURE: We screened 394 primary neuroblastomas and 52 tumor-derived cell lines with a panel of 11q and 11p polymorphic markers to determine the frequency of chromosome 11 allelic deletion, and to differentiate partial deletions of chromosome 11q (unb[11q] LOH) from whole chromosome loss. RESULTS: Allelic deletion occurred most frequently at cytogenetic band 11q23 and was detected in 161 primary neuroblastomas (41%) and 18 cell lines (35%). Eighty-seven tumors (22%) had unb[11q] LOH with a heterogeneous distribution of deletion breakpoints. Unb[11q] LOH was highly correlated with age > 1 year at diagnosis (P = 0.008), stage 4 disease (P = 0.001), unfavorable Shimada histopathology (P < 0.001), and assignment to a high-risk therapeutic protocol (P < 0.001), and was inversely correlated with MYCN amplification (P = 0.018). Patients whose tumors showed unb[11q] LOH were less likely to survive (P < 0.001), but there was only a trend towards an independent prognostic influence in multivariate analyses. CONCLUSIONS: Thus, structural rearrangements resulting in unb[11q] LOH commonly occur during the malignant evolution of high-risk neuroblastomas with single-copy MYCN.     

Distal chromosome 17 gains in neuroblastomas detected by comparative genomic hybridization (CGH) are associated with a poor clinical outcome

PROCEDURE: To establish the significance of chromosome 17 aberrations in the biology of neuroblastomas, the fresh-frozen material of 53 primary neuroblastomas (average patient age: 20.8 months; stage 1 or 2: n = 10; stage 3: n = 10; stage 4: n = 10; stage 4s: n = 23) was studied by means of comparative genomic hybridization (CGH). Follow-up data were available for 52 of 53 cases studied (average follow-up period: 26.4 months). Except for one, all cases had previously been analyzed for MYCN status (semiquantitative Southern blot analysis). Studies of LOH 1p36 (VNTR-PCR) had been performed on 28 of 53 cases. RESULTS: Chromosome 17 gains were detected in 46 of 53 (86.8%) cases. Whole chromosome gains were mostly restricted to localized tumors (stage 1 or 2: 9 of 10 cases; stage 4s:19 of 23; stage 3: 2 of 10; stage 4:0 of 10 cases), whereas distal 17 gains were significantly associated with clinically advanced tumor stages and patients aged over 1 year at diagnosis. Univariate analyses revealed a statistically significant correlation of distal 17q gains with overall survival (P< 0.01, MYCN amplification: P< 0.01; 1p deletion: P< 0.01) and an elevated recurrency rate (17q: P= 0.02, MYCN amplification: P = 0.05; 1p deletion P= 0.3). There was a strong coincidence of distal 17q gains and 1p deletion or MYCN amplification (P < 0.01). CONCLUSION: Our data indicate that distal chromosome 17q gains are of major prognostic relevance for neuroblastoma patients. However, studies on a larger series of tumors have to be performed to assess whether or not these alterations are independent prognostic markers of a poor clinical outcome.     

Genetic analysis of p73 localized at chromosome 1p36.3 in primary neuroblastomas

BACKGROUND: Human p73, a novel homolog of p53, has recently been cloned and mapped at chromosome 1p36.3, the locus for putative tumor suppressor gene(s) of neuroblastoma (NBL) and other cancers. p73, like p53, inhibits growth and induces apoptosis in neuroblastoma and osteosarcoma cell lines. PROCEDURE: To test the hypothesis that p73 is a NBL suppressor gene, we examined expression, allelo-typing, and mutation of the p73 gene in primary human neuroblastomas. Loss of heterozygosity (LOH) for p73 was performed in 272 primary NBLs using a CT repeat polymorphic marker, which we found in intron 9 of the p73 gene. RESULTS: p73 LOH was observed in 28 out of 151 (19%) informative cases. The high frequency of p73 LOH was significantly associated with sporadic neuroblastomas (P< 0.001), MYCN amplification (P< 0.001), and advanced stages (P< 0.05). Mutational analyses by PCR-SSCP (single strand conformation polymorphism) revealed two mis-sense mutations in 140 NBLs, one somatic and one germline. CONCLUSION: Thus, the present results have shown that mutation of p73 is infrequent in NBLs, although the p73 locus is frequently lost in advanced stage tumors. These suggest that p73 may not be a tumor suppressor in the classic Knudson manner.     

Deletion mapping of 14q32 in human neuroblastoma defines an 1,100-kb region of common allelic loss

BACKGROUND: We analyzed loss of heterozygosity (LOH) in 54 primary neuroblastomas (NBs) using 12 microsatellite markers on 14q32, and found that 31% (17/54) NBs showed LOH. PROCEDURE: The smallest region of overlap (SRO) was identified between D14S62 and D14S987. RESULTS: There was no statistical correlation between LOH and any clinicopathologic features, including age, stage, amplification of MYCN, and ploidy. A sequence-ready bacterial artificial chromosome (BAC) contig was constructed, and the minimum tiling path of six BACs covered the SRO; the physical length of this region was no larger than 1,000 kb. CONCLUSIONS: Our findings support the existence of a putative tumor-related gene on 14q32 for the tumorigenesis of NB.     

Somatostatin receptor type 2 gene expression in neuroblastoma, measured by competitive RT-PCR, is related to patient survival and to somatostatin receptor imaging by indium -111-pentetreotide

BACKGROUND: We previously reported that human neuroblastoma cell lines and primary neuroblastoma tumors expressed a variable amount of mRNA for type 2 somatostatin (sst2) receptor gene. We also found that high level of sst2 expression were positively related to patient survival. PROCEDURE: We studied retrospectively 49 primary neuroblastomas. To detect and measure sst2 mRNA expression we developed a quantitative RT-PCR based on competitive PCR. When possible the number of MYCN copies was also measured with competitive PCR. RESULTS;. We found that the lowest level of sst2 mRNA was detected in advanced stages of neuroblastomas (stage IV) when compared with the other stages (P< 0.005). Patients with high levels of sst2 expression (>7 x 10(7) molecules/microg RNA) had a cumulative survival better than those with low sst2 expression (P < 0.0005). This predictive independent value of sst2 (P= 0.005) is retained after stratification for N-myc amplification. Finally we verified that the ex vivo sst2 gene expression in tumor samples was positively related (P < 0.01) to the in vivo semiquantitative determination of sst2 protein, assessed by 111In-pentetreotide imaging. CONCLUSIONS: Our data indicate that the measurement of sst2 mRNA measurement could represent a relevant tool in the prediction of neuroblastoma outcome, independently from MYCN amplification.     

Bilateral adrenal neuroblastoma is different.

BACKGROUND/AIMS: Bilateral adrenal neuroblastoma is rare and can be due to multifocal primary or contralateral metastasis. Staging is confusing in these patients and treatment guidelines are difficult to set. The present study examines the clinical, biological and therapeutic features of bilateral adrenal neuroblastoma. METHODS: We identified 4 cases primarily located in both adrenals out of 148 neuroblastomas treated between 1992 and 2006. We studied the clinicopathological findings and biological features, including MYCN amplification, and analyzed the treatment strategies and results. RESULTS: All patients were younger than 6 months of age and all had multiple liver metastases. Three had subcutaneous nodules and massive liver enlargement. All underwent chemotherapy prior to operation. Two babies had large bilateral tumors without preservable glands and underwent bilateral adrenalectomy. Both had MYCN gene amplification and died of widespread (brain and bone) metastases some weeks later. In the remaining two patients adrenalectomy was performed on the side of the larger tumor with tumor enucleation on the other side to preserve hormonal function followed by 2 courses of mild chemotherapy in one patient. These tumors were not amplified. Both of these children are doing well. CONCLUSIONS: Bilateral adrenal neuroblastomas fit neither into stage 4 s nor into stage 4. Their clinical behavior is exceptional with a number of multicystic forms, variable MYCN amplification, widespread metastases and a high mortality. Bilateral adrenalectomy is sometimes unavoidable, but unilateral removal with contralateral enucleation, partial resection or observation are valid alternatives. Mortality is higher than in regular stage 4 s cases. This particular group of neuroblastomas required individually tailored therapeutic strategies based on the size, extent and prognostic markers.     

Increased expression of the MYCN oncogene in human neuroblastoma cells and possible, new therapeutic approaches

Human neuroblastomas of advanced stages often display amplification with a consecutive enhanced expression of the MYCN oncogene. Enhanced MYCN expression is thought to contribute in a causative manner to the progression of neuroblastomas, but the mechanisms by which this may occur have remained unclear. By transfecting human neuroblastoma cells that display a normal MYCN expression with the human MYCN oncogene, we have generated a cell line with enhanced MYCN expression and thereby were able to compare the biological and biochemical properties of the transfected and non-transfected cells. We have demonstrated autocrine growth factors in the MYCN-transfected, but not the non-transfected, neuroblastoma cells. Identification of the primary structures of these factors may help to develop specific antagonists in order to improve the therapy of advanced neuroblastomas. Currently, this could be done by application of genistein or tumor necrosis factor. As we could demonstrate for the first time, the dietary constituent genistein is able to inhibit the proliferation of neuroblastoma cells with enhanced and normal MYCN expression, but also that of cells derived from other solid pediatric tumors. In contrast, tumor necrosis factor is able to inhibit selectively the proliferation of neuroblastoma cells with enhanced MYCN expression. We suggest that tumor necrosis factor might improve the therapy of advanced human neuroblastomas.     

急性淋巴细胞白血病6q16.3微卫星DNA缺失及临床相关性研究

目的定位儿童急性淋巴细胞白血病（ALL）杂合性缺失（LOH）的集中区,探讨新的肿瘤抑制基因及与临床相关性。方法取6q16.3的15个微卫星,利用聚合酶链反应-变性凝胶电泳-银染技术分析儿童ALL等位基因LOH的情况,进行生物信息学分析;探讨与临床预后因素的相关性。结果至少一个位点的LOH率为32.7%,D6S1709-D6S1028及D6S2160-D6S1580是集中高频缺失区,早期复发病例的LOH率高于无早期复发病例;谷氨酸受体6基因（GRIK2）为一有力的候选抑癌基因;两个区域有可能代表新基因的表达序列标签12个;LOH与白细胞总数、病态细胞数、核型分析、早期复发及免疫分型有相关性。结论D6S1709-D6S1028和D6S2160-D6S1580为目前国内外所确定的最精确缺失区,可能存在一个或数个肿瘤抑制基因,6q16.3LOH的发生与ALL预后有一定关系。     

Prognostic value of MYCN and ID2 overexpression in neuroblastoma

BACKGROUND: The molecular mechanisms driven by overexpression of the MYCN gene in neuroblastoma are not well known. Whether MYCN overexpression in the absence of genomic amplification, or ID2 overexpression has prognostic value remains controversial. PROCEDURE: Ninety-nine neuroblastic tumors from Memorial Sloan-Kettering Cancer Center and 12 neuroblastoma cell lines were analyzed by Affymetrix U95v2 Microarray System. The expression levels of the genes MYCN and ID2 were determined by RT-PCR and immunohistochemistry and the clinical value of the overexpression of both genes was determined. RESULTS: MYCN genomic amplification with overexpression was prognostic for survival (P = 0.0005). Stage 4 patients with MYCN amplification but without overexpression, had no increased likelihood of death, whereas cases with MYCN overexpression but no genomic amplification showed a low survival (P = 0.0096). ID2 did not correlate with MYCN expression (R = -0.23 for tumors and -0.27 for cell lines) or with survival (P = 0.8746). CONCLUSIONS: MYCN amplification was not related to clinical outcome in the absence of overexpression in neuroblastoma tumors. ID2 expression appears to be independent of MYCN expression and lacks prognostic value.     

Survivin mRNA levels are associated with biology of disease and patient survival in neuroblastoma: a report from the children's oncology group

Alterations in apoptotic mechanisms favoring cell survival may be vital for modifying tumor behavior. Survivin, an inhibitor of apoptosis, and caspase 8, a proapoptotic enzyme, are key players in cellular apoptotic mechanisms. We investigated whether the levels of survivin and caspase 8 and the ratio between these 2 apoptotic factors correlate with tumor biology and predicts outcome in patients with neuroblastoma. Survivin and caspase 8 levels were quantified in 38 primary tumor specimens and analyzed individually and in relation to each other. High survivin expression and high survivin:caspase 8 ratios were associated with MYCN amplification, unfavorable histology, and high-risk group of disease (P<0.0008). High survivin mRNA levels were associated with worse overall survival (P=0.02) although the median follow up was only 22.6 months with a range of 1 day to 3.3 years. Low caspase 8 expression was associated with stage 4 disease, high-risk group, MYCN amplification, and unfavorable histology. Although the survivin:caspase 8 ratio was associated with these risk factors, the ratio did not improve the predictive value of survivin alone in this small series. Quantifying multiple apoptotic genes in neuroblastoma may supplement current risk stratification. Moreover, categorizing aberrant apoptotic gene expression in neuroblastoma may translate into novel therapeutic targets.     

Intensified chemotherapy increases the survival rates in patients with stage 4 neuroblastoma with MYCN amplification

PURPOSE: Patients with high-risk neuroblastoma who have multiple copies of MYCN fare much worse than do those without MYCN amplification; however, it has not been clarified whether intensified chemotherapy with or without blood stem cell transplantation can alter the extremely poor prognosis of patients with amplified MYCN. METHODS AND RESULTS: Between 1985 and 1999, 301 patients older than age 12 months with stage 4 neuroblastoma were treated. From January 1985 to February 1991, 80 patients with stage 4 neuroblastoma with and without MYCN amplification uniformly received induction chemotherapy with regimen A(1) (cyclophosphamide 1,200 mg/m(2) and vincristine 1.5 mg/m(2) on day 1, tetra-hydropyranyl [THP]-Adriamycin 40 mg/m(2) on day 3, and cisplatin 90 mg/m(2) on day 5). Among 22 patients with MYCN amplification, nine (40.9%) achieved a complete remission and seven (31.8%) underwent stem cell transplantation. Of 58 patients without MYCN amplification, 43 (74.1%) achieved a complete remission and 14 (24.1%) underwent stem cell transplantation. The 5-year relapse-free survival rates were 23.2% for stage 4 patients with MYCN amplification and 33.3% for those without MYCN amplification (P = 0.029); the 5-year overall survival rates were 32.8% for stage 4 patients with MYCN amplification and 42.8% for those without MYCN amplification (P > 0.05). From March 1991 to June 1998, patients with stage 4 neuroblastoma who had 10 or more copies of MYCN were treated with regimen A(3) (cyclophosphamide 1,200 mg/m(2) per day on days 1 and 2, THP-Adriamycin 40 mg/m(2) on day 3, etoposide 100 mg/m(2) per day on days 1 to 5, and cisplatin 25 mg/m(2) per day on days 1 to 5); those with fewer than 10 copies of MYCN received regimen new A (cyclophosphamide 1,200 mg/m on day 1, THP-Adriamycin 40 mg/m on day 3, etoposide 100 mg/m per day on days 1 to 5, and cisplatin 90 mg/m on day 5), which is similar in intensity to regimen A. Among 88 patients with MYCN amplification, 63 (71.6%) achieved a complete remission and 63 (71.68%) underwent stem cell transplantation. Of 133 patients without MYCN amplification, 93 (69.9%) achieved a complete remission and 71 (53.4%) underwent stem cell transplantation. The 5-year relapse-free survival rates were 36.0% for stage 4 patients with MYCN amplification and 32.2% for those without MYCN amplification (P > 0.05), the 5-year overall survival rates were 34.0% for stage 4 patients with MYCN amplification and 38.9% for those without MYCN amplification (P > 0.05). The difference in relapse-free survival rates was significantly different (P = 0.003) between patients with MYCN-amplified tumor treated before (regimen A(1)) versus after 1991 (regimen A(3)). CONCLUSIONS: With the use of the more intensive induction regimen A plus blood stem cell transplantation for MYCN-amplified patients, survival curves for those with or without MYCN amplification now appear similar. Higher doses of chemotherapy may ameliorate the effect of MYCN amplification in patients with high-risk neuroblastoma.     

New definition of low-risk neuroblastoma using stage, age, and 1p and MYCN status

Data from patients with localized and stage 4S neuroblastoma were analyzed to define a new, extended low-risk group that does not require postoperative chemotherapy. Nine hundred eight patients with stage 1 to 3 and 4S disease without MYCN amplification were included. The prognostic impacts of age, stage, serum lactate dehydrogenase (LDH) activity, histology, and alterations of chromosomes 1p, 11q, and 3p were analyzed. By univariate analysis, alterations of chromosomes 1p and 11q were correlated with poor event-free survival (EFS) and overall survival (OS). Chromosome 3p alterations were prognostic only for EFS. Age, stage, and histology were found prognostic for EFS and OS. Stage 3 patients older than 2 years showed the worst outcome and were excluded from multivariate analysis. By multivariate analysis, status of 1p (P = 0.005, hazard ratio [HR] 3.6) and 11q (P = 0.024, HR 2.8) proved prognostic for EFS but only 1p status (P = 0.009, HR 3.0) for OS. The new low-risk group was defined as no MYCN amplification and either stage 1, stage 2 without 1p alterations, stage 3 two years of age or younger without 1p alteration, or stage 4S. These patients had a better outcome (3-year EFS 88.0 +/- 1.3%, 3-year OS 97.4 +/- 0.6%) than stage 2 and 3 patients with 1p alterations and stage 3 patients older than 2 years (3-year EFS 51.7 +/- 6.5%, P < 0.001; 3-year OS 83.4 +/- 4.5%; P < 0.001). The authors conclude that postoperative chemotherapy is required only in a small group of patients with localized and stage 4S disease without MYCN amplification.     

伴骨髓转移的神经母细胞瘤患儿初诊时骨髓染色体核型的临床意义

目的总结伴骨髓转移的神经母细胞瘤(NB)患儿初诊时骨髓染色体核型分析结果,探讨其临床意义。方法采用G显带的方法,对2015年1月至2017年12月北京儿童医院血液肿瘤中心收治的伴骨髓转移的NB患儿进行染色体核型分析,总结临床特点、分析预后,随访至2018年12月31日。结果1.共120例患儿,男74例,女46例,≥18个月者98例(81.7%)。染色体正常组60例,其中56例(93.3%)国际神经母细胞瘤分期系统(INSS)-Ⅳ期,余4例为INSS-Ⅳs期;低危(LR)2例,中危(MR)9例,高危(HR)49例(81.7%);7例患儿MYCN基因扩增。染色体异常组60例患儿均为INSS-Ⅳ期,MR 1例,余59例(98.3%)均为HR,14例MYCN基因扩增。2.染色体异常患儿60例中单纯数目异常和结构异常者分别为4例、14例,42例患儿同时合并染色体数目及结构异常。数目异常方面,21号、10号、11号染色体缺失最为常见;结构异常方面涉及11q、1p、3p区段的异常发生率高。3.染色体正常组患儿随访时间为4~44个月,17例出现肿瘤进展或复发;染色体异常组患儿随访时间2~42个月,其中31例出现肿瘤进展或复发。所有患儿3年累积总生存率和累积无事件生存率分别为60.0%、48.4%;染色体正常组患儿3年累积生存率为74.2%,3年累积无事件生存率为65.7%;染色体异常组患儿3年累积生存率为47.5%,3年累积无事件生存率为24.9%;出现进展或复发患儿染色体数目异常以10号染色体缺失常见,结构异常以11q、1p、2p区域较多。结论NB患儿肿瘤细胞染色体异常率高,但重复率低,个体间差异明显。10号染色体缺失、11q、1p、2p区域结构异常可能为提示NB预后不良因素;通过骨髓标本进行肿瘤染色体核型分析可行,可为更精准的危险度分层和治疗提供依据。     

Prognostic impact of molecular genetic alterations in hepatoblastoma

BACKGROUND: During recent years, we identified characteristic genetic alterations in sporadic hepatoblastoma (HB). These include loss of heterozygosity (LOH) at the chromosomal region 11p15.5, LOH on chromosome arms 1p and 1q, activating mutations in exon 3 of the beta-catenin gene, as well as overexpression of the c-met oncogene, which encodes the hepatocyte growth factor receptor. We now wanted to evaluate the prognostic relevance of these abnormalities concerning the outcome in a large group of patients. PROCEDURE: All but 7 of 56 patients with HB were treated either with primary resection for small tumors, or neo-adjuvant chemotherapy with ifosfamide, cisplatin and doxorubicin (IPA) before delayed surgery in case of extended disease and additional adjuvant IPA therapy in all cases. Seven tumors were primarily resected and adjuvantly treated with different cytotoxic drugs. LOH 11p15.5, LOH 1p, and LOH 1q were detected in tumor tissue in comparison to normal liver and/or peripheral blood leukocytes by PCR based microsatellite analysis. Beta-catenin mutations were analysed with SSCP, deletion screening and direct sequencing. RT-PCR was used for identification of c-met mRNA overexpression. The results were correlated with the tumors' stage, histological type and epithelial differentiation, as well as with the patients' outcome. RESULTS: Overall disease-free survival after median follow-up of 5 years was 43/56 patients (77%). LOH 11p15.5 was found in 15/56, LOH1p in 11/53, LOH1q in 7/53 and beta-catenin mutations in 25/55 HB. 13/23 HB had a c-met overexpression. LOH 11p15.5 and LOH 1p were significantly more often found in embryonal HB, while there was no correlation of other genetic alterations with histological type or differentiation. Furthermore, statistical analysis revealed no correlation of any of these disorders with initial tumor stage, nor with the patients' outcome. CONCLUSION: None of the investigated molecular genetic alterations are suited to serve as a prognostic indicator in HB. Further investigations, especially genetic screening of tumor tissue may reveal prognostic markers for this neoplasm.