Christian Brinkschmidt

Gain of Chromosome Arm 17q and Adverse Outcome in Patients with Neuroblastoma

BACKGROUND Gain of genetic material from chromosome arm 17q (gain of segment 17q21-qter) is the most frequent cytogenetic abnormality of neuroblastoma cells. This gain has been associated with advanced disease, patients who are > or =1 year old, deletion of chromosome arm 1p, and amplification of the N-myc oncogene, all of which predict an adverse outcome. We investigated these associations and evaluated the prognostic importance of the status of chromosome 17. METHODS We compiled molecular cytogenetic analyses of chromosome 17 in primary neuroblastomas in 313 patients at six European centers. Clinical and survival information were collected, along with data on 1p, N-myc, and ploidy. RESULTS Unbalanced gain of segment 17q21-qter was found in 53.7 percent of the tumors, whereas the chromosome was normal in 46.3 percent. The gain of 17q was characteristic of advanced tumors and of tumors in children > or =1 year of age and was strongly associated with the deletion of 1p and amplification of N-myc. No tumor showed amplification of N-myc in the absence of either deletion of 1p or gain of 17q. Gain of 17q was a significant predictive factor for adverse outcome in univariate analysis. Among the patients with this abnormality, overall survival at five years was 30.6 percent (95 percent confidence interval, 21 to 40 percent), as compared with 86.0 percent (95 percent confidence interval, 78 to 91 percent) among those with normal 17q status. in multivariate analysis, gain of 17q was the most powerful prognostic factor, followed by the presence of stage 4 disease and deletion of 1p (hazard ratios, 3.4, 2.3, and 1.9, respectively). CONCLUSIONS Gain of chromosome segment 17q21-qter is an important prognostic factor in children with neuroblastoma.

Comparative genomic hybridization of ductal carcinoma in situ of the breast—evidence of multiple genetic pathways

There is strong evidence that ductal carcinoma in situ (DCIS) represents a precursor lesion of invasive breast cancer. In order to analyse specific chromosomal alterations of DCIS, 38 paraffin‐embedded specimens of DCIS and six associated invasive carcinomas were examined by means of comparative genomic hybridization (CGH). Losses of 16q material were seen almost exclusively in well‐ and intermediately‐differentiated DCIS. These two subgroups differed in the average number of genetic imbalances, 2·5 and 5·5 respectively. Additionally, a higher frequency of gains of 1q and losses of 11q material was seen in intermediately‐differentiated in contrast to well‐differentiated DCIS. Poorly‐differentiated DCIS displayed a higher frequency of amplifications (17q12, 11q13) and a higher average rate of genetic imbalances (7·1). Analysis of adjacent invasive breast carcinoma revealed a genetic pattern almost identical to the one seen in the DCIS counterpart. These data characterize DCIS as a genetically far‐advanced, heterogeneous lesion and as a direct precursor of invasive breast cancer. Copyright

Different genetic pathways in the evolution of invasive breast cancer are associated with distinct morphological subtypes.

Invasive breast cancer shows a wide range of morphological differentiation, associated with differences in prognosis, but as yet, the underlying genetic mechanisms cannot be accounted for. In order to establish a model of the possible progression from the different subtypes of ductal carcinoma in situ (DCIS) to invasive breast cancer, 77 selected cases of invasive breast cancer representing distinct morphological subtypes were investigated by means of comparative genomic hybridization (CGH). There was a high degree of genetic homology between tubular and tubulo‐lobular carcinoma and well‐differentiated DCIS, and between ductal invasive carcinoma G3 and poorly differentiated DCIS. Highly differentiated invasive breast cancers were characterized by a loss of 16q and a low average number of aberrations per case. In high‐grade tumours, losses of this chromosomal region were seen with a much lower frequency in cases with evidence of an aneuploid tumour status. These data demonstrate the close genetic similarity of well‐, intermediately, and poorly differentiated DCIS and distinct morphological types of invasive breast carcinoma, providing further evidence that DCIS is a direct precursor lesion of invasive breast cancer and that various evolutionary genetic pathways exist. Copyright

Chromosomal aberrations associated with invasion in papillary superficial bladder cancer

Non‐invasive and invasive papillary transitional cell carcinomas of stages pTa and pT1 represent the first steps of tumour progression in bladder cancer. In order to analyse different chromosomal alterations of pTa and pT1 superficial bladder cancer, 46 tumour specimens were examined by comparative genomic hybridization (CGH). Losses of chromosome 9 material (11/20) and gains of chromosome 17 material (6/20) were frequently found in pTa tumours. Stage pT1 tumours were characterized by gains of chromosome 1q (14/26; including amplification at 1q21–q24 in three cases) and chromosome 17 material (15/26), as well as by losses of 11p (15/26) and 11q (13/26). Other loci frequently showing losses in pT1 tumours were 2q (9/26), 4q (10/26), 5q (9/26), 8p (10/26), 9p (9/26), 9q (12/26), 10q (8/26), 17p (7/26), and 18q (8/26). Amplifications were detected at 8q21/22, 5q21, 7q36, 10p14, 10p12, 10q25, 12q12, and 12q14. The most striking differences between grade 2 pTa and pT1 tumours were gains of 1q (P<0·01) and losses at 2q (P<0·025), 10q (P<0·05), 11p (P<0·01), 11q (P<0·01), and 17p (P<0·05), as well as the total number of aberrations (pTa grade 2: 4·1; pT1 grade 2: 8·6 aberrations per tumour). These data show characteristic chromosomal aberrations associated with invasion in superficial bladder cancer.

Alternative lengthening of telomeres is associated with chromosomal instability in osteosarcomas

Telomere maintenance is regarded as a key mechanism in overcoming cellular senescence in tumor cells and in most cases is achieved by the activation of telomerase. However there is at least one alternative mechanism of telomere lengthening (ALT) which is characterized by heterogeneous and elongated telomeres in the absence of telomerase activity (TA). We evaluated the prevalence of TA, gene expression of telomerase subunits and ALT in relation to telomere morphology and function in matrix producing bone tumors and in osteosarcoma cell lines and present evidence of a direct association of ALT with telomere dysfunction and chromosomal instability. Telomere fluorescence in situ hybridization (T-FISH) in ALT cells revealed elongated and shortened telomeres, partly in unusual configurations and loci, dicentric marker chromosomes and signal-free chromosome ends. Free ends give rise to end-to-end associations and may induce breakage-fusion-bridge cycles resulting in an increased number of complex chromosomal rearrangements, as detected by multiplex-FISH (M-FISH). We propose that ALT cannot be seen as an equivalent to telomerase activity in telomere maintenance. Its association with telomere dysfunction and chromosomal instability may have major implications for tumor progression.

Unequivocal Delineation of Clinicogenetic Subgroups and Development of a New Model for Improved Outcome Prediction in Neuroblastoma

PURPOSE Neuroblastoma is a genetically heterogeneous pediatric tumor with a remarkably variable clinical behavior ranging from widely disseminated disease to spontaneous regression. In this study, we aimed for comprehensive genetic subgroup discovery and assessment of independent prognostic markers based on genome-wide aberrations detected by comparative genomic hybridization (CGH). MATERIALS AND METHODS Published CGH data from 231 primary untreated neuroblastomas were converted to a digitized format suitable for global data mining, subgroup discovery, and multivariate survival analyses. RESULTS In contrast to previous reports, which included only a few genetic parameters, we present here for the first time a strategy that allows unbiased evaluation of all genetic imbalances detected by CGH. The presented approach firmly established the existence of three different clinicogenetic subgroups and indicated that chromosome 17 status and tumor stage were the only independent significant predictors for patient outcome. Important new findings were: (1) a normal chromosome 17 status as a delineator of a subgroup of presumed favorable-stage tumors with highly increased risk; (2) the recognition of a survivor signature conferring 100% 5-year survival for stage 1, 2, and 4S tumors presenting with whole chromosome 17 gain; and (3) the identification of 3p deletion as a hallmark of older age at diagnosis. CONCLUSION We propose a new regression model for improved patient outcome prediction, incorporating tumor stage, chromosome 17, and amplification/deletion status. These findings may prove highly valuable with respect to more reliable risk assessment, evaluation of clinical results, and optimization of current treatment protocols.

Comparative genomic hybridization (CGH) analysis of stage 4 neuroblastoma reveals high frequency of 11q deletion in tumors lacking MYCN amplification

We have studied the occurrence and association of 11q deletions with other chromosomal imbalances in Stage 4 neuroblastomas. To this purpose we have performed comparative genomic hybridization (CGH) analysis on 50 Stage 4 neuroblastomas and these data were analyzed together with those from 33 previously published cases. We observed a high incidence of 11q deletion in Stage 4 neuroblastoma without MYCN amplification (59%) whereas 11q loss was only observed in 15% of neuroblastomas with MYCN‐amplification (p = 0.0002) or 11% of cases with 1p deletion detected by CGH (p = 0.0001). In addition, 11q loss showed significant positive correlation with 3p loss (p = 0.0002). Event‐free survival was poor and not significantly different for patients with or without 11q deletion. Our study provides further evidence that Stage 4 neuroblastomas with 11q deletions represent a distinct genetic subgroup that typically shows no MYCN‐amplification nor 1p deletion. Moreover, it shows that neuroblastomas with 11q deletion also often present 3p deletion. This genetic subgroup shows a similar poor prognosis as MYCN amplified 4 neuroblastomas.

Comparative genomic hybridization (CGH) analysis of neuroblastomas--an important methodological approach in paediatric tumour pathology.

Comparative genomic hybridization (CGH) was applied to 35 neuroblastomas to obtain a global view of genetic imbalances. Results were validated by means of Southern blot hybridization (detection of N‐myc amplification), loss of heterozygosity (LOH) studies (detection of deletion 1p), and interphase cytogenetics [dual labelling fluorescence in situ hybridization (FISH) of centromeric 17 and erbB‐2]. CGH allowed sensitive detection of N‐myc amplification and chromosome 1p deletion, representing the most established prognostic markers of neuroblastoma. In addition, a high rate of chromosome 17 aberrations (63 per cent) with possible prognostic relevance was observed. Previously unreported high level copy number increases indicating oncogene amplification were mapped to chromosome subbands 2p13–14 and 3q24–26. Other recurrent regional chromosomal aberrations were localized on 11q, 12q, 13q, 14q, and 15q. CGH results were fully consistent with data of Southern blot analysis and LOH study, as well as interphase cytogenetics. These results show that CGH is a sensitive method for the detection of all prognostically relevant genetic alterations in neuroblastomas; that CGH considerably simplifies the detection of these alterations, resulting in a single methodological approach; and that CGH is a powerful tool to elucidate previously unknown genetic changes in neuroblastomas.

Osteochondroma: MR imaging of tumor-related complications

Abstract. Osteochondromas can be complicated by mechanical irritation, compression or injury of adjacent structures, fracture, malignant transformation, and postoperative recurrence. Magnetic resonance imaging represents the most valuable imaging modality in symptomatic cases, because it can demonstrate typical features of associated soft tissue pathology, which can be differentiated from malignant transformation. Reactive bursae formation presents as an overlying fluid collection with peripheral contrast enhancement. Dislocation, deformation, and signal alterations of adjacent soft tissue structures can be observed in different impingement syndromes caused by osteochondromas. Magnetic resonance imaging provides excellent demonstration of arterial and venous compromise and represents the method of choice in cases with compression of spinal cord, nerve roots, or peripheral nerves, depicting changes in size, position, and signal intensity of the affected neural structures. Malignant transformation as the most worrisome complication occurs in approximately 1 % of solitary and 5–25 % of multiple osteochondromas. Magnetic resonance imaging is the most accurate method in measuring cartilage cap thickness, which represents an important criterion for differentiation of osteochondromas and exostotic (low-grade) chondrosarcomas. Cartilage cap thickness exceeding 2 cm in adults and 3 cm in children should raise the suspicion for malignant transformation. Finally, MR imaging can detect postoperative recurrence by depiction of a recurrent mass presenting typical morphological features of a cartilage-forming lesion.

Multicentre analysis of patterns of DNA gains and losses in 204 neuroblastoma tumors: how many genetic subgroups are there?

PROCEDURE Analysis of comparative genomic hybridization (CGH) data of 120 tumors from four different studies, and data of 84 previously unpublishied tumors, allowed delineation of at least six different genetic subsets of neuroblastomas. RESULTS AND CONCLUSIONS A small number of tumors show no detectable imballances. A second group of tumors presents with gains and losses of whole chromosomes and is found predominantly in prognostically favorable stage 1 and 2 tumors. The remaining groups are characterized by the presence of partial chromosome imbalances, and are found mostly in stage 3, 4, and 4S tumors. The third group shows 17q gain without 11q loss, 1p loss, or MYCN amplification (MNA). The fourth group has 1p deletion or MNA, and finally, a fifth group shows 11q loss without 1p deletion or MNA, and is found mainly in stage 4 tumors. The latter group is significantly associated with losses of 3p, 4p, and 14q.