Updates on the cytogenetics and molecular genetics of bone and soft tissue tumors: chondrosarcoma and other cartilaginous neoplasms

Nomograms to predict lung metastasis in malignant primary osseous spinal neoplasms and cancer-specific survival in lung metastasis subgroup

Purpose

To construct and validate nomograms for predicting lung metastasis probability in patients with malignant primary osseous spinal neoplasms (MPOSN) at initial diagnosis and predicting cancer-specific survival (CSS) in the lung metastasis subgroup.

Methods

A total of 1,298 patients with spinal primary osteosarcoma, chondrosarcoma, Ewing sarcoma, and chordoma were retrospectively collected. Least absolute shrinkage and selection operator (LASSO) and multivariate logistic analysis were used to identify the predictors for lung metastasis. LASSO and multivariate Cox analysis were used to identify the prognostic factors for 3- and 5-year CSS in the lung metastasis subgroup. Receiver operating characteristic (ROC) curves, calibration curves, and decision curve analyses (DCA) were used to estimate the accuracy and net benefits of nomograms.

Results

Histologic type, grade, lymph node involvement, tumor size, tumor extension, and other site metastasis were identified as predictors for lung metastasis. The area under the curve (AUC) for the training and validating cohorts were 0.825 and 0.827, respectively. Age, histologic type, surgery at primary site, and grade were identified as the prognostic factors for the CSS. The AUC for the 3- and 5-year CSS were 0.790 and 0.740, respectively. Calibration curves revealed good agreements, and the Hosmer and Lemeshow test identified the models to be well fitted. DCA curves demonstrated that nomograms were clinically useful.

Conclusion

The nomograms constructed and validated by us could provide clinicians with a rapid and user-friendly tool to predict lung metastasis probability in patients with MPOSN at initial diagnosis and make a personalized CSS evaluation for the lung metastasis subgroup.

Dedifferentiated Chondrosarcoma: Diagnostic Controversies and Emerging Therapeutic Targets

PURPOSE OF REVIEW

The pathogenesis of dedifferentiated chondrosarcoma is controversial, and no genetic abnormality has consistently been identified in the disease. Focusing on the diagnostic challenges encountered in dedifferentiated chondrosarcoma, the following review aims at summarizing the tumor's active neoplastic pathways while highlighting therapeutic modalities that could potentially be explored to enhance patient survivorship.

RECENT FINDINGS

Owing to the challenging examination of small needle biopsy sampling as well as the disease's overlapping morphological and immunohistochemical features with other bone and soft-tissue sarcomas, the diagnosis of dedifferentiated chondrosarcoma can be problematic. While combined doxorubicin- and cisplatin-based regimens remain the first-line systemic chemotherapy in the disease, ~50% of tumors carry EXT1/2 or IDH1/2 mutations, advancing EXT or IDH inhibitors as potential alternative therapies, respectively. Despite systemic chemotherapy, dedifferentiated chondrosarcoma remains an aggressive tumor with dismal prognosis and limited survival. A multidisciplinary collaboration across multiple cancer centers is warranted to yield an accurate diagnosis, understand the disease's underlying pathogenesis, develop adequate treatment, and improve patient survivorship.

Mesenchymal Chondrosarcoma from Diagnosis to Clinical Trials

Mesenchymal chondrosarcoma (MCS) is a rare subtype of chondrosarcoma with a poor prognosis. Although these tumors are sensitive to radiotherapy/chemotherapy, the standard treatment for localized MCS is only surgical resection, and there are no established treatment guidelines for patients with advanced and metastatic MCS. Due to the low incidence of MCS, the pathology of these tumors is still unknown, and other therapeutic options are lacking. Some studies show the potential role of the PDGF/PPI3K/AKT, PKC/RAF/MEK/ERK, and pRB pathways, and BCL2 overexpression in the pathogenesis of MCS. These findings provide an opportunity to use protein kinases and BCL2 inhibitors as potential therapy in MCS. In this review, we summarize the current knowledge about MCS diagnosis and treatment options. We show the immunological and molecular biomarkers used in the diagnosis of MCS. In addition, we discuss the known prognostic and predictive factors in MCS. Finally, we present the novel trends, including targeted therapies and ongoing clinical trials using protein kinase inhibitors and the death receptor 5 (DR5) agonist, which may be the focus of future MCS treatment studies.

Prevalence of Petrooccipital Fissure Fusion: Osteological Study with Application to Approaches to the Skull Base and Imaging Interpretation

INTRODUCTION

The petrooccipital fissure (POF) has relevance to skull base approaches, various tumors and craniosynostoses, and some cases of age-related hearing loss. However, the prevalence of fusion and classification of such is rarely found in the extant medical literature.

METHODS

One-hundred and 10 dry human skulls (220 sides) were used for this study. The skulls were evaluated for fusion of the POF. Both the endocranial and exocranial aspects of the POF were analyzed. A classification scheme was developed to better describe the location of POF fusion.

RESULTS

A fused POF was identified on 36 sides (16.4%) and commonly found bilaterally (11%). Of these, 30 sides (83.3%) were completely fused (type I) and 6 sides (2.7%) were partially fused (types II and III). For the partially fused fissures, the fused part was on all but 2 sides with the most anterior portion of the petrous part of the temporal bone and adjacent clivus (type II). For the 2 sides (both right sides), the fusion was more posteriorly located between the petrous part of the temporal bone and lateral clivus (type III). Fusion of the POF was more often found in specimens with a partially or fully ossified petroclival ligament. Completely fused POF was positively correlated to sides with an intrajugular bony septum.

CONCLUSIONS

A POF fusion was relatively common and associated with an ossified petroclival ligament and intrajugular bony septation. Such a prevalence is important for clinicians and skull base surgeons interpreting imaging of the skull base.

Clinical Characteristics, Pathology and Outcome of 237 Patients With Synovial Sarcoma: Single Center Experience

BACKGROUND

Synovial sarcoma (SS) is a rare soft tissue sarcoma. Available data regarding survival outcomes of patients with SS still remains limited. In this study, a single center retrospective analysis was performed to investigate the clinical characteristics, pathology and survival outcomes in patients with SS in China.

METHODS

Patient data were systematically reviewed at the National Cancer Center from January 2015 to December 2020. The general information and treatment condition of patients were collected. Overall survival (OS) was evaluated using the Kaplan-Meier and Cox regression method.

RESULTS

A total of 237 consecutive patients were included in this study (follow-up cut-off date: December, 2020). The median age of patients involved was 35 years (ranging from 5 to 83 years) and the mean tumor diameter was 5.3 cm (ranging from .2 to 26.0 cm). The main findings of the immunohistochemical staining analyses were EMA (111/156) (71%), keratin (32/64) (50.0%), keratin (12/20) (60%), keratin (42/70) (60%), S-100 (18/160) (11%), BCL-2 (128/134) (96%), CD99 (137/148) (93%) and TLE1 (23/26) (88%). It was found that 109 patients (66%) were presented with monophasic subtype and 55 (34%) with biphasic subtype. A total of 137 patients were tested by FISH method and 119 patients (87%) demonstrated SS18 rearrangement, whereas 18 patients (13%) did not show SS18 rearrangement. Generally, it was found that the 3-year OS rate was 86% and the 3-year DFS was 55%. Results of univariate analysis revealed that age, tumor size, tumor site, radiotherapy and targeted therapy were significantly correlated with the overall survival (P < .05). Further, multivariate Cox regression analysis revealed that age, tumor size and radiotherapy were significantly associated with OS (P < .05).

CONCLUSIONS

In conclusion, this study shows that the outcomes of patients with SS significantly decrease with age and tumor size. It was evident that radiotherapy is an independent and positive prognostic factor for patients with SS. In addition, it was shown that the prognosis of SS varies with tumor location. For instance, primary tumors in lower extremities have a higher prognosis, whereas tumors located in thorax have a lower prognosis.

miR-26a Reverses Multidrug Resistance in Osteosarcoma by Targeting MCL1

The multidrug resistance (MDR) acquired in human osteosarcoma is a huge obstacle for effective chemotherapy. Recently, microRNA-26a (miR-26a) has been associated with the pathogenesis and progression of osteosarcoma. However, whether it regulates MDR in osteosarcoma is unknown. We show here that miR-26a expression declines in chemoresistant osteosarcoma after neoadjuvant chemotherapy, and its expression correlates with clinical outcome. In addition, compared with sensitive parental cells, miR-26a expression also declines in osteosarcoma MDR cells, together suggesting a negative correlation between miR-26a expression and MDR development in osteosarcoma. We also show that the enforced expression of miR-26a reverses MDR in osteosarcoma cells, and conversely, miR-26a knockdown confers MDR in chemosensitive osteosarcoma cells treated with doxorubicin, methotrexate, or cisplatin. Mechanistically, miR-26a directly targets the pro-survival protein myeloid cell leukemia 1 (MCL1), and in turn, the enforced expression of MCL1 markedly antagonizes miR-26a-decreased MDR in osteosarcoma MDR cells, therefore demonstrating that miR-26a reverses MDR in osteosarcoma by targeting MCL1. Lastly, miR-26a reverses resistance to doxorubicin in osteosarcoma MDR cells xenografted in nude mice. Collectively, these results reveal a negative role and the underlying mechanism of miR-26a in the regulation of MDR in human osteosarcoma, implying a potential tactic of manipulating miR-26a for overcoming MDR in osteosarcoma chemotherapy.

Biological Heterogeneity of Chondrosarcoma: From (Epi) Genetics through Stemness and Deregulated Signaling to Immunophenotype

Chondrosarcoma (ChS) is a primary malignant bone tumor. Due to its heterogeneity in clinical outcomes and resistance to chemo- and radiotherapies, there is a need to develop new potential therapies and molecular targets of drugs. Many genes and pathways are involved in in ChS progression. The most frequently mutated genes are isocitrate dehydrogenase ½ (IDH1/2), collagen type II alpha 1 chain (COL2A1), and TP53. Besides the point mutations in ChS, chromosomal aberrations, such as 12q13 (MDM2) amplification, the loss of 9p21 (CDKN21/p16/INK4A and INK4A-p14ARF), and several gene fusions, commonly occurring in sarcomas, have been found. ChS involves the hypermethylation of histone H3 and the decreased methylation of some transcription factors. In ChS progression, changes in the phosphatidylinositol 3-kinase/protein kinase B/mammalian target of rapamycin (PI3K-AKT-mTOR) and hedgehog pathways are known to play a role in tumor growth and chondrocyte proliferation. Due to recent discoveries regarding the potential of immunotherapy in many cancers, in this review we summarize the current state of knowledge concerning cellular markers of ChS and tumor-associated immune cells. This review compares the latest discoveries in ChS biology from gene alterations to specific cellular markers, including advanced molecular pathways and tumor microenvironment, which can help in discovering new potential checkpoints in inhibitory therapy.

Nomograms to predict lung metastasis probability and lung metastasis subgroup survival in malignant bone tumors

The aim of this study was to construct and validate nomograms for predicting lung metastasis and lung metastasis subgroup overall survival in malignant primary osseous neoplasms. Least absolute shrinkage and selection operator, logistic and Cox analyses were used to identify risk factors for lung metastasis in malignant primary osseous neoplasms and prognostic factors for overall survival in the lung metastasis subgroup. Further, nomograms were established and validated. A total of 3184 patients were collected. Variables including age, histology type, American Joint Committee on Cancer T and N stage, other site metastasis, tumor extension and surgery were extracted for the nomograms. The authors found that nomograms could provide an effective approach for clinicians to identify patients with a high risk of lung metastasis in malignant primary osseous neoplasms and perform a personalized overall survival evaluation for the lung metastasis subgroup.

Translational Windows in Chordoma: A Target Appraisal

Chordomas are rare tumors that are notoriously refractory to chemotherapy and radiotherapy when radical surgical resection is not achieved or upon recurrence after maximally aggressive treatment. The study of chordomas has been complicated by small patient cohorts and few available model systems due to the rarity of these tumors. Emerging next-generation sequencing technologies have broadened understanding of this disease by implicating novel pathways for possible targeted therapy. Mutations in cell-cycle regulation and chromatin remodeling genes have been identified in chordomas, but their significance remains unknown. Investigation of the immune microenvironment of these tumors suggests that checkpoint protein expression may influence prognosis, and adjuvant immunotherapy may improve patient outcome. Finally, growing evidence supports aberrant growth factor signaling as potential pathogenic mechanisms in chordoma. In this review, we characterize the impact on treatment opportunities offered by the genomic and immunologic landscape of this tumor.

Targeting regulation of cyclin dependent kinase 9 as a novel therapeutic strategy in synovial sarcoma

Synovial sarcomas hold a low genomic complexity, making it distinct from other types of soft-tissue sarcomas. Many studies focused on targeting the SS18-SSX fusion protein, which presents in over 90% of human synovial sarcomas. This protein acts as an oncogenic promoter in the tumorigenesis of synovial sarcomas, making it an ideal therapeutic target. However, to date there have been no effective strategies targeting SS18-SSX for the treatment of synovial sarcomas. Therefore, it is an urgent need to identify alternative therapeutic targets. More recently, CDK9, a protein involved in RNA transcription regulation, has been investigated for its role in the pathogenesis of cancer. However, the expression and function of CDK9 in synovial sarcomas remains to be elucidated. In the present study, we found that CDK9 was to be largely localized to the cell nucleus, and highly expressed in all tested human synovial sarcoma cell lines and over 90% of human sarcoma tissue microarray samples. High-CDK9 expression was associated with a poorer patient prognosis of human sarcomas. Inhibition of CDK9, with either siRNA or a CDK9 inhibitor, prevented synovial sarcoma cell growth and proliferation in a dose-dependent manner. This was also accompanied with a reduction in the phosphorylation of RNA polymerase II and an increase in the expression of anti-apoptotic proteins. Moreover, CDK9 inhibition decreased sarcoma cell spheroid formation and cell motility. Collectively, these findings highlight the importance of CDK9 in human synovial sarcoma cell growth and proliferation. Therefore, CDK9 may represent a promising target for the treatment of synovial sarcomas. © 2018 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 37:510-521, 2019.

Prognostic factors for patients with chondrosarcoma: A survival analysis based on the Surveillance, Epidemiology, and End Results (SEER) database (1973-2012)

•

First, it is a population-based study which can provide big sample size.

•

Second, similar articles about chondrosarcoma using big data are lacking.

•

Third, the relationship between treatment type and survival outcomes was analyzed in detail.

Current reports on prognostic factors for chondrosarcoma mainly involve patients in treatment centers. Few are based on multicenter or multi-eras. We analyzed existing data from the Surveillance, Epidemiology, and End Results (SEER) database to investigate the risk factors for survival outcomes. All patients with chondrosarcoma from 1973 to 2012 were identified. 3737 patients were eligible and included. In survival analysis, patient had good survival outcome if the patient was female, young, with localized stage, well grade, small tumor size, treated with surgery, while patient was male, old, with distant stage, undifferentiated grade, tumor size <50 mm, located in vertebral or pelvic bones, underwent radiation had bad survival outcome. Surgery types from having best survival outcomes to worst were local excision, radical excision, amputation, no surgery. ‘Well’ and ‘moderately’ grade seems to be suitable for local excision, but ‘poorly’ and ‘undifferentiated’ grade suitable for wide local excision. Multivariate COX regression analysis showed year of diagnosis, sex, age of diagnosis, stage, grade, tumor site, surgery, radiation were independent risk factors. Year of diagnosis, sex, age of diagnosis, stage, grade, tumor site, surgery, radiation were independent risk factors. Excision is a better treatment than amputation. Doctors can use wide local excision to treat chondrosarcoma, especially when encountering high grade chondrosarcoma or pelvic chondrosarcoma.

5'-methylschweinfurthin G reduces chondrosarcoma tumor growth

New treatment options are urgently required in the field of chondrosarcoma, particularly of chondrosarcomas with a well-differentiated hyaline cartilage-like extracellular matrix (e.g., collagen II and proteoglycan-rich) phenotype, notoriously resistant to drug penetration, and having potential of progression towards higher grade. We investigated the feasibility of using 5'-methylschweinfurthin G (MeSG) as a tumor suppressor agent in the Swarm rat chondrosarcoma, an intermediate- to high-grade chondrosarcoma model, having a hyaline cartilage-like phenotype. Tumor cell culture studies were performed to identify their proliferative and cytotoxicity sensitivity to MeSG. Tumor burden mice were treated with MeSG and analyzed for tumor growth, morphology and regression. The chondrosarcoma tumor cells had a half maximum cytotoxicity concentration (IC₅₀ ) of 35 nM MeSG; approximately 300-fold less than freshly isolated rat chondrocytes (IC₅₀ of 11 µM). Multiple injections of MeSG (20 mg/kg, body weight) resulted in reduced/eliminated tumor growth over a 17-day period in mice, and an 83% reduction (p = 0.023) in tumor mass. Three out of ten MeSG treated mice had complete elimination of tumor. Tumors of treated mice had a decrease in chondrosarcoma cell proliferation (p = 0.012) and an increase in cell death (p = 0.030) compared with tumors of control mice. These findings in an animal model demonstrate the effectiveness of MeSG for treatment of rat chondrosarcomas, and may have the potential use as a therapeutic option for the difficult-to-treat intermediate-to high-grade hyaline cartilage-like chondrosarcoma. © 2017 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 36:1283-1293, 2018.

Advances in chromosomal translocations and fusion genes in sarcomas and potential therapeutic applications

Chromosomal translocations and fusion genes are very common in human cancer especially in subtypes of sarcomas, such as rhabdomyosarcoma, Ewing's sarcoma, synovial sarcoma and liposarcoma. The discovery of novel chromosomal translocations and fusion genes in different tumors are due to the advancement of next-generation sequencing (NGS) technologies such as whole genome sequencing. Recently, many novel chromosomal translocations and gene fusions have been identified in different types of sarcoma through NGS approaches. In addition to previously known sarcoma fusion genes, these novel specific fusion genes and associated molecular events represent important targets for novel therapeutic approaches in the treatment of sarcomas. This review focuses on recent advances in chromosomal translocations and fusion genes in sarcomas and their potential therapeutic applications in the treatment of sarcomas.

Infiltration of CD8 T Cells and Expression of PD-1 and PD-L1 in Synovial Sarcoma

Tumors expressing programmed death ligand 1 (PD-L1) interact with the corresponding negative-signal generating immune receptor on the surface of CD8 T cells, PD-1, thereby suppressing antitumor activity. Therapeutics blocking this interaction have shown promise in various cancers by restoring functional antitumor T-cell activity. We explored the degree of PD-L1, PD-1, and CD8 expression in a retrospective analysis of 29 clinical synovial sarcoma samples. Quantitative immunohistochemistry and multiplex immunofluorescence were used to determine relative quantification of CD8⁺ and PD-1⁺ T cells and PD-L1 expression within the intratumor area and the interface between the tumor and the surrounding nontumor tissue (i.e., invasive margin), and colocalization of these factors, respectively. PD-L1, PD-1, and CD8 cell densities in the tumor-invasive margins were significantly higher in the metastatic tumors than the primary tumors (P < 0.01), and PD-L1, PD-1, and CD8 cell densities were all significantly positively correlated with one other (P < 0.0001). PD-1 cell density in the tumor-invasive margin was significantly associated with worse progression-free survival. Multiplex immunofluorescence demonstrated coexpression of PD-1 and CD8 on lymphocytes within the invasive margin, as well as relative proximity between PD-1⁺ CD8 cells and PD-L1⁺ tumor cells. Our results provide a preclinical rationale for screening of patients with synovial sarcoma for the colocalization of CD8, PD-1, and PD-L1, which may be a marker for response to PD-1 blockade therapy. Cancer Immunol Res; 5(2); 118-26. ©2016 AACR.

Articular Chondromatosis and Chrondroid Metaplasia in Transgenic TAg Mice

The C3(1)/SV40 T antigen transgenic mouse model for which rapid mammary and prostate tumor development has been documented uses the FVB/N mouse as a background strain. In this study, where the background strain used was the C57BL/6J mouse, neither mammary nor prostate tumors developed over periods of up to 40 weeks. However, a disturbance of hyaline cartilage in joints was observed similar to that found in synovial chondromatosis in humans. In addition, cartilage thickening in the external ears and cartilaginous metaplasia of the ascending aorta also occurred. This suggests that rearrangement of the transgene occurred in breeding on the C57BL background, thus modifying its expression. It raises the possibility that the genetic changes induced by the SV40 T antigen transforming sequence are important in cartilage homeostasis.

Primary intra-articular sarcoma: a clinicopathological study of 15 cases

AIMS

To assess the clinical and histopathological spectrum of primary intra-articular sarcomas.

METHODS AND RESULTS

Fifteen patients were identified as having primary intra-articular sarcomas and the clinical and pathological features were evaluated. There were nine males and six females who ranged in age from 16 to 84 (mean 44) years. All tumours originated in the knee joint. The pathological diagnoses included: five synovial sarcoma, three extraskeletal myxoid chondrosarcomas, two high-grade myxofibrosarcoma (one conventional, one epithelioid), two undifferentiated pleomorphic sarcoma (one with giant cells) and one each myxoinflammatory fibroblastic sarcoma, conventional hyaline chondrosarcoma, and high-grade myofibroblastic sarcoma. All tumours were treated by segmental resection or amputation. Adjuvant therapy was given in selected cases. Follow-up ranged from 11 to 150 months. Of patients with follow-up, two died of disease; one developed pulmonary metastases after 6 years and was then lost to follow-up. Nine patients were alive and free of disease 12-150 months after diagnosis.

CONCLUSIONS

Primary sarcomas of the joints are very rare and most frequently affect the knee. Our experience indicates that synovial sarcoma and extraskeletal myxoid chondrosarcoma are the most common intra-articular sarcomas.

Intralesional curettage and cementation for low-grade chondrosarcoma of long bones: retrospective study and literature review

Background

Various treatment strategies for low-grade chondrosarcomas with variable outcomes have been reported in the literature. The aim of this study was to assess the oncological and functional outcomes associated with intralesional curettage followed by adjuvant therapy comprising high-speed burring, thermal cauterization, and bone cementation with polymethylmethacrylate.

Methods

We performed a retrospective review of 21 consecutive patients with intramedullary low-grade chondrosarcoma of long bones treated by intralesional curettage and adjuvant therapy comprising high-speed burring, thermal cauterization, and cementation at our institution from 2007 to 2012.

Results

The average age of the patients was 48.7 (range, 18–71) years. There were 7 male and 14 female patients. The mean follow-up period was 58.4 (range, 26–85) months after surgery. The treated lesions were located in the proximal humerus (n =10), proximal tibia (n =6), and distal femur (n =5). At the average follow-up time point of 58.4 (range, 26–85) months, no patient had developed local recurrence and no distant metastases were observed. The average Musculoskeletal Tumor Society score among all 21 patients was 95% (84–100).

Conclusions

The combination of intralesional curettage, application of high-speed burring, thermal cauterization, and cementation is an effective treatment strategy for low-grade intramedullary chondrosarcoma of long bones. Excellent oncological and functional results can be obtained.

Synovial sarcoma: defining features and diagnostic evolution

Synovial sarcoma (SS) is a malignant mesenchymal neoplasm with variable epithelial differentiation, with a propensity to occur in young adults and which can arise at almost any site. It is generally viewed and treated as a high-grade sarcoma. As one of the first sarcomas to be defined by the presence of a specific chromosomal translocation leading to the production of the SS18-SSX fusion oncogene, it is perhaps the archetypal "translocation-associated sarcoma," and its translocation remains unique to this tumor type. Synovial sarcoma has a variety of morphologic patterns, but its chief forms are the classic biphasic pattern, of glandular or solid epithelial structures with monomorphic spindle cells and the monophasic pattern, of fascicles of spindle cells with only immunohistochemical or ultrastructural evidence of epithelial differentiation. However, there is significant morphologic heterogeneity and overlap with a variety of other neoplasms, which can cause diagnostic challenge, particularly as the immunoprofile is varied, SS18-SSX is not detected in 100% of SSs, and they may occur at unusual sites. Correct diagnosis is clinically important, due to the relative chemosensitivity of SS in relation to other sarcomas, for prognostication and because of the potential for treatment with specific targeted therapies in the near future. We review SS, with emphasis on the diagnostic spectrum, recent immunohistochemical and genetic findings, and the differential diagnosis.

Chondrosarcoma of bone

Chondrosarcoma is a cartilage forming neoplasm, which is the second most common primary malignancy of bone. Clinicians who treat chondrosarcoma patients must determine the grade of the tumor, and must ascertain the likelihood of metastasis. Acral lesions are unlikely to metastasize, regardless of grade, whereas axial, or more proximal lesions are much more likely to metastasize than tumors found in the distal extremities with equivalent histology. Chondrosarcoma is resistant to both chemotherapy and radiation, making wide local excision the only treatment. Local recurrence is frequently seen after intralesional excision, thus wide local excision is sometimes employed despite significant morbidity, even in low-grade lesions. Chondrosarcoma is difficult to treat. The surgeon must balance the risk of significant morbidity with the ability to minimize the chance of local recurrence and maximize the likelihood of long-term survival.

Swarm chondrosarcoma: a continued resource for chondroblastic-like extracellular matrix and chondrosarcoma biology research

Since its first description over four decades ago, the Swarm chondrosarcoma (Swarm rat chondrosarcoma, SRC) remains a valuable tool for studies of chondroblastic-like extracellular matrix (ECM) biology and as an animal model of human chondrosarcoma of histological grades I-III. Moreover, articular joints and skeletal anomalies such as arthritis as well as cartilage regeneration, skeletal development, tissue engineering, hard tissue tumorigenesis and space flight physiology are advanced through studies in hyaline cartilage-like models. With more than 500 articles published since the first report on the characteristics of mucopolysaccharides (glycosaminoglycans) of the tumor in 1971, several transplantable tumor and cell lines have been developed by multiple laboratories worldwide. This review describes the characterization of SRC tumors and cell lines, including the use of SRC lines as a resource for isolation and characterization of several ECM elements that have become vital for the advancement of our understanding of cartilage biology. Also presented is the importance of pertubation of ECM components and the influence of the tumor microenvironment on disease progression. Therapeutic failure and currently pursued avenues of intervention utilizing the SRC lines in treatment of chondrosarcoma are also discussed.

Recurrent and novel SS18-SSX fusion transcripts in synovial sarcoma: description of three new cases

Synovial sarcoma (SS) is an aggressive type of tumor, comprising approximately 10 % of soft tissue sarcomas. Over 90 % of SS cases are characterized by the t(X;18)(p11.2;q11.2) translocation, which results mainly in the formation of oncogenic SS18-SSX1 or SS18-SSX2 fusions. In a typical SS18-SSX fusion transcript, exon 10 of SS18 is fused to exon 6 of SSX1/2. However, several variant fusion transcripts have been already described. In the present study, we examined the fusion transcript type in a series of 40 primary untreated SS tumor specimens using reverse transcription polymerase chain reaction and fluorescence in situ hybridization assay. We detected SS18-SSX1 transcript in 22 (55 %) patients and SS18-SSX2 transcript in 17 (42.5 %) patients, while in one patient, none of SS18-SSX1/2 fusion transcripts were identified. Among the cases under study, two tumors carried novel SS18-SSX1 and SS18-SSX2 variant translocations that were allegedly created by an alternative splicing, and in additional case, an unusual translocation variant previously described by other group was found. Our data suggest that alternative splicing may play an important role in novel fusion transcript formation, and additionally we show that it may be a recurrent event in SS. Furthermore, we describe the first case of a complex rearrangement possibly linking SS to REPS2 gene.

12q amplification defines a subtype of extraskeletal osteosarcoma with good prognosis that is the soft tissue homologue of parosteal osteosarcoma

Extraskeletal osteosarcomas are rare tumors with neoplastic cells synthesizing bone, usually associated with poor prognosis. We present the case of a 40-year-old man with an extraskeletal osteosarcoma that was treated by surgery and adjuvant radiotherapy. Thirteen years after the diagnosis, he remains disease-free, without any recurrences or metastases. Histopathological analysis favored the diagnosis of chondroblastic extraskeletal osteosarcoma grade II. G-banding, comparative genomic hybridization (CGH), and real-time PCR for the MDM2 and CDK4 genes were performed to describe the genetic profile of this tumor and revealed aberrations that are common findings of parosteal osteosarcomas. Ring chromosomes, giant marker chromosomes, and a telomeric association were found with G-banding. CGH revealed that 12q was amplified in the ring and giant markers identified by G-banding. Real-time PCR for MDM2 and CDK4 confirmed the amplification of these genes located in 12q. Our findings suggest that a variant of extraskeletal osteosarcoma, which is genotypically similar to parosteal osteosarcoma, exists and is associated with good prognosis.

Molecular pathology and its diagnostic use in bone tumors

Bone tumors are considered by most pathologists difficult to diagnose as they are rare, have overlapping morphology, need radiological correlation, and the usefulness of immunohistochemistry is limited, making conventional morphology the cornerstone of the diagnosis. Over the past decade, more and more has become known of the molecular background of bone tumors. Three groups of bone tumors are recognized, namely, tumors with specific translocations combined with a relatively simple karyotype involving chromosomal translocations (Ewing sarcoma, aneurysmal bone cyst), tumors with specific gene mutations or amplifications (chondrosarcoma, fibrous dysplasia, chordoma), and sarcomas with genetic instability and as a consequence complex karyotypes (osteosarcoma). Technical advancements will rapidly reveal new alterations in the more rare sarcoma subtypes for which the molecular background has remained enigmatic. Opening the archives and using new technologies, as well as refinement of existing technologies for decalcified paraffin-embedded tissue, may bring to light more specific genetic aberrations in bone tumors that can be applied in molecular diagnostics in the near future.

Extraskeletal cartilaginous, osseous, and chordoid tumors in children and adolescents

Extraskeletal cartilaginous, osseous, and chordoid tumors are extraordinarily rare in children and adolescents. These lesions are diagnostically challenging due to their rarity and their overlap with metastatic osteosarcoma, reactive or metabolic calcifying and bone-forming masses, various pseudosarcomatous proliferations such as myositis ossificans, and other rare genetic or metabolic disorders. This article reviews the clinicopathologic features and differential diagnosis of extraskeletal cartilaginous, osseous, and chordoid neoplasms in the first two decades of life and highlights the use of diagnostic adjuncts.

Similar cytogenetic findings in two synchronous secondary peripheral chondrosarcomas in a patient with multiple osteochondromas

Secondary peripheral chondrosarcoma is a malignant chondroid tumor arising in a benign precursor, either an osteochondroma or an enchondroma. Multiple osteochondromas syndrome (MO) is an autosomal dominant skeletal disorder associated with bony growths in the form of osteochondromas that occasionally undergo malignant transformation to secondary peripheral chondrosarcomas. We describe the genetic examination of three secondary peripheral chondrosarcomas that had arisen synchronously from osteochondromas in a patient with MO by chromosome banding, high resolution chromosomal comparative genomic hybridization, and mutation analysis of the EXT1 and EXT2 genes. In two of the tumors (the third was not genetically informative), very similar chromosome abnormalities were found, indicating that they must somehow be part of the same neoplastic process in spite of being anatomically distinct.

Downstream and intermediate interactions of synovial sarcoma-associated fusion oncoproteins and their implication for targeted therapy

Synovial sarcoma (SS), an aggressive type of soft tissue tumor, occurs mostly in adolescents and young adults. The origin and molecular mechanism of the development of SS remain only partially known. Over 90% of SS cases are characterized by the t(X;18)(p11.2;q11.2) translocation, which results mainly in the formation of SS18-SSX1 or SS18-SSX2 fusion genes. In recent years, several reports describing direct and indirect interactions of SS18-SSX1/SSX2 oncoproteins have been published. These reports suggest that the fusion proteins particularly affect the cell growth, cell proliferation, TP53 pathway, and chromatin remodeling mechanisms, contributing to SS oncogenesis. Additional research efforts are required to fully explore the protein-protein interactions of SS18-SSX oncoproteins and the pathways that are regulated by these partnerships for the development of effective targeted therapy.

Bone Lesions of the Head and Neck

This article describes the clinical, radiographic, and pathologic features of tumors and tumorlike lesions affecting the bones of the head and neck region. Emphasis is placed on common bone lesions affecting the craniofacial skeleton, particularly those that occur with more frequency or those that are unique to this part of the skeleton. Several of these lesions pose a diagnostic challenge to the pathologist. To ensure that a correct diagnosis is rendered, it is of utmost importance that accurate and detailed clinical and radiographic information is available.

Primary malignant bone tumors--recent developments

Primary malignant bone tumors are rare sarcomas with an estimated frequency of about 2900 new cases per year; they constitute less than 0.2% of all cancers diagnosed in the United States. The diagnosis and management of these neoplasms require a team approach, which includes orthopaedic surgeons, radiologists, pathologists, and oncologists. With this approach and current treatment modalities, the 5-year survival for the most common malignant bone tumors, osteosarcoma and Ewing sarcoma, are 70% and 60%, respectively. This review will summarize recent developments and advances in molecular pathogenesis of the more common primary malignant bone neoplasms.

Cytogenetic findings in 14 benign cartilaginous neoplasms

Benign cartilaginous tumors represent a spectrum of neoplastic processes with variable clinical and pathologic presentations. These tumors are histologically characterized by the presence of chondrocytes surrounded by a cartilaginous matrix. Few studies describe karyotypic abnormalities in these benign lesions. We report a series of 14 chondromas from a single institution. Conventional cytogenetics was performed on short term cultures from all cases. Clonal chromosome aberrations were found in nine tumors. One soft tissue chondroma contained three clones with t(6;12)(q12;p11.2), t(3;7)(q13;p12), and der(2)t(2;18)(p11.2;q11.2). Three periosteal chondromas displayed random structural aberrations of chromosomes 2, 3, 6, 7, and 11 and loss of chromosome 13. Among the enchondromas, three tumors displayed chromosome losses, one contained a complex translocation involving chromosomes 12, 15, and 21 as well as an inv(2)(p21q31),t(12;15;21)(q13;q14;q22) and a separate enchondroma showed a translocation involving chromosomes 12 and 22. Our data suggest that considerable cytogenetic heterogeneity exists among benign chondromatous tumors.

(124)I-iodopyridopyrimidinone for PET of Abl kinase-expressing tumors in vivo

Because of the recent development of an iodopyridopyrimidinone Abl protein kinase inhibitor (PKI), (124)I-SKI-212230 ((124)I-SKI230), we investigated the feasibility of a PET-based molecular imaging method for the direct visualization of Abl kinase expression and PKI treatment.

METHODS

In vitro pharmacokinetic properties, including specific and nonspecific binding of (124)I-SKI230 to its Abl kinase target and interaction with other PKIs, were assessed in cell-free medium and chronic myelogenous leukemia (CML) cells overexpressing BCR-Abl (K562), in comparison with BT-474 cells that are low in Abl expression. In a xenograft tumor model, we assessed the in vivo pharmacokinetics of (124)I-SKI230 using PET and postmortem tissue sampling. We also tested a paradigm of (124)I-SKI230 PET after treatment of the animal with a dose of Abl-specific PKI for the monitoring of the tumor response.

RESULTS

In vitro studies confirmed that SKI230 binds to Abl kinase with nanomolar affinity, that selective uptake occurs in cell lines known to express Abl kinase, that RNAi knock-down supports specificity of cellular uptake due to Abl kinase, and that imatinib, an archetype Abl PKI, completely displaces SKI230. With SKI230, we obtained successful in vivo PET of Abl-expressing human tumors in a nude rat. We were also able to demonstrate evidence of substrate inhibition of in vivo radiotracer uptake in the xenograft tumor after treatment of the animal as a model of PKI treatment monitoring.

CONCLUSION

These results support the hypothesis that molecular imaging using PET will be useful for the study of in vivo pharmacodynamics of Abl PKI molecular therapy in humans.

Chondrosarcomas of the base of the skull in Ollier's disease or Maffucci's syndrome--three case reports and review of the literature

Ollier's disease is a rare disease characterized by constitutional bone dysplasia with multiple enchondromas. The combination of haemangioma and chondromatoses is known as Maffucci's syndrome. Malignant degeneration of bone dysplasia into chondrosarcoma is a well-known complication, but a lesion of the base of the skull is exceptional. It is a slowly growing low-grade malignant tumour. Three new cases of chondrosarcoma of the base of the skull occurring in one patient with Marfucci's syndrome and two patients with Ollier's disease are reported and these cases are discussed in the light of the literature. A multidisciplinary approach, comprising surgery and radiotherapy, achieved good results.

Gene translocations in musculoskeletal neoplasms

Establishing the best diagnosis for musculoskeletal neoplasms requires a multidisciplinary approach using clinical, radiographic, and histologic analyses. Despite this rigorous approach, establishing accurate diagnoses and prognoses remains challenging. Improved diagnostic methods are expected as unique molecular signals for specific bone and soft tissue cancers are identified. We performed a systematic review of the best available evidence to explore three major applications of molecular genetics that will best benefit clinical management of musculoskeletal neoplasms: diagnostic, prognostic, and therapeutic applications. The specific questions addressed in this systematic review are: (1) What sets of histopathologic sarcoma subtypes will benefit from molecular evaluation and diagnosis? (2) What molecular methods are best applied to histopathologic sarcomas to distinguish between major subtypes? (3) How do the molecular patterns discovered on genetic diagnosis affect prognosis of certain sarcomas? (4) Which sarcoma translocations can benefit from an improved response and outcome using existing and forthcoming pharmacogenetic approaches targeting molecular events? This review summarizes recent advances in molecular genetics that are available and will soon be available to clinicians to better predict outcomes and subsequently help make future treatment decisions.

LEVEL OF EVIDENCE

Level IV, diagnostic study. See the Guidelines for Authors for a complete description of levels of evidence.

The clinical approach towards chondrosarcoma

This review provides an overview of the histopathology, classification, diagnostic procedures, and therapy of skeletal chondrosarcoma. Chondrosarcomas that arise de novo are primary chondrosarcomas, whereas chondrosarcomas developing superimposed on pre-existing benign cartilage neoplasms such as enchondromas or osteochondromas are referred to as secondary chondrosarcomas. Conventional chondrosarcomas can be categorized according to their location in bone into central, peripheral, and juxtacortical chondrosarcomas. Histological grading is related to prognosis; however, it is also subject to interobserver variability. Rare subtypes of chondrosarcoma, including dedifferentiated, mesenchymal, and clear cell chondrosarcoma, are discussed as well. Magnetic resonance imaging is necessary to delineate the extent of the intraosseous and soft tissue involvement preoperatively. Computed tomography is especially recommended in the pelvis and other flat bones where it may be difficult to discern the pattern of bone destruction and the presence of matrix mineralization. Wide, en-bloc excision is the preferred surgical treatment in intermediate- and high-grade chondrosarcoma. In low-grade chondrosarcoma confined to the bone, extensive intralesional curettage followed by local adjuvant treatment and filling the cavity with bone graft has promising long-term clinical results and satisfactory local control. Chondrosarcomas are relatively radiotherapy resistant; therefore, doses >60 Gy are needed in attempts to achieve local control after incomplete resection. Irradiation with protons or other charged particles seems beneficial in this curative situation. Chemotherapy is only possibly effective in mesenchymal chondrosarcoma, and is of uncertain value in dedifferentiated chondrosarcoma. Potential new systemic treatment targets are being discussed.

Chordoma: the nonsarcoma primary bone tumor

Chordomas are rare, slowly growing, locally aggressive neoplasms of bone that arise from embryonic remnants of the notochord. These tumors typically occur in the axial skeleton and have a proclivity for the spheno-occipital region of the skull base and sacral regions. In adults, 50% of chordomas involve the sacrococcygeal region, 35% occur at the base of the skull near the spheno-occipital area, and 15% are found in the vertebral column. Craniocervical chordomas most often involve the dorsum sella, clivus, and nasopharynx. Chordomas are divided into conventional, chondroid, and dedifferentiated types. Conventional chordomas are the most common. They are characterized by the absence of cartilaginous or additional mesenchymal components. Chondroid chordomas contain both chordomatous and chondromatous features, and have a predilection for the spheno-occipital region of the skull base. This variant accounts for 5%-15% of all chordomas and up to 33% of cranial chordomas. Dedifferentiation or sarcomatous transformation occurs in 2%-8% of chordomas. This can develop at the onset of the disease or later. Aggressive initial therapy improves overall outcome. Patients who relapse locally have a poor prognosis but both radiation and surgery can be used as salvage therapy. Subtotal resection can result in a stable or improved status in as many as 50% of patients who relapse after primary therapy. Radiation therapy may also salvage some patients with local recurrence. One series reported a 2-year actuarial local control rate of 33% for patients treated with proton beam irradiation.

Tumor-biology and current treatment of skull-base chordomas

Chordomas are rare, slow growing tumors of the axial skeleton, which derive from the remnants of the fetal notochord. They can be encountered anywhere along the axial skeleton, most commonly in the sacral area, skull base and less commonly in the spine. Chordomas have a benign histopathology but exhibit malignant clinical behavior with invasive, destructive and metastatic potential. Genetic and molecular pathology studies on oncogenesis of chordomas are very limited and there is little known on mechanisms governing the disease. Chordomas most commonly present with headaches and diplopia and can be readily diagnosed by current neuroradiological methods. There are 3 pathological subtypes of chordomas: classic, chondroid and dedifferentiated chordomas. Differential diagnosis from chondrosarcomas by radiology or pathology may at times be difficult. Skull base chordomas are very challenging to treat. Clinically there are at least two subsets of chordoma patients with distinct behaviors: some with a benign course and another group with an aggressive and rapidly progressive disease. There is no standard treatment for chordomas. Surgical resection and high dose radiation treatment are the mainstays of current treatment. Nevertheless, a significant percentage of skull base chordomas recur despite treatment. The outcome is dictated primarily by the intrinsic biology of the tumor and treatment seems only to have a secondary impact. To date we only have a limited understanding this biology; however better understanding is likely to improve treatment outcome. Hereby we present a review of the current knowledge and experience on the tumor biology, diagnosis and treatment of chordomas.

Establishment of novel human dedifferentiated chondrosarcoma cell line with osteoblastic differentiation

Dedifferentiated chondrosarcoma is a rare, highly malignant variant of chondrosarcoma in which a high-grade sarcoma coexists with a low-grade chondroid tumor. We herein review a case of dedifferentiated chondrosarcoma with an osteosarcoma omit component that occurred in the distal femur of a 38-year-old man. We established the cell line (NDCS-1) from a pleural effusion of the metastatic lung tumor. The cell line was characterized by a the G-banded karyotype, polymerase chain reaction (PCR) single-strand conformation polymorphism analysis, spectral karyotyping, and reverse transcriptase PCR (RT-PCR). The tumor exhibited complex karyotypes and a high frequency of chromosomal amplication with p53 mutation. This tumor revealed an osteoblastic and chondroblastic character in vitro and in severe combined immunodeficiency mice. The expression and phosphorylation of platelet-derived growth factor receptor-beta, which seemed to play a major role in the malignant phenotype of chondrosarcoma, was confirmed by RT-PCR and Western blotting. To our knowledge, this is the first report of the establishment of a human dedifferentiated chondrosarcoma.

Desmoplastic small round cell tumor: Using FISH as an ancillary technique to support cytologic diagnosis in an unusual case

Desmoplastic small round cell tumor is a rare and aggressive neoplasm that predominantly affects young males. In almost all cases, a reciprocal translocation is present resulting in the fusion of the Ewing sarcoma gene with the Wilms' tumor gene. Here we describe an unusual case occurring in a 59-year-old male, in which fluorescence in situ hybridization (FISH) was used in conjunction with immunohistochemical studies to confirm the diagnosis. To our knowledge, this is the first reported case of using FISH as an ancillary technique to confirm the cytologic diagnosis of this tumor.

Clonality studies in sacral chordoma

Chordomas are rare, slow-growing, primary malignant skeletal neoplasms. Chromosome analysis, telomere reduction and telomere activity, DNA microsatellite, and loss of heterozygosity studies have been performed on chordomas; however, the clonality status (monoclonal versus polyclonal proliferation) is unknown. The primary purpose of this study was to determine whether sacral chordoma is monoclonal or polyclonal in origin with the use of a polymorphic X-linked gene (AR; alias HUMARA) and X-chromosome inactivation studies. DNA was harvested from tumor and corresponding normal tissue from eight women (37-71 years) with chordoma. Clonality was determined using an X chromosome inactivation protocol and a polymorphic human androgen receptor gene (AR) located on the X chromosome. The procedure required a methylation-specific polymerase chain reaction (PCR) and determination of the ratio of active to inactive X chromosomes. Results were informative for seven of the eight women, with two separate X-linked alleles seen for the AR gene in the normal tissue. Expression of AR gene alleles from each of the two X chromosomes was present in the chordoma tumor, indicating a polyclonal proliferation in all seven women. Most solid tumors and skeletal neoplasms are polyclonal in nature. Our study indicates that chordoma is polyclonal in its pattern of proliferation.

Gene expression dynamics in deer antler: mesenchymal differentiation toward chondrogenesis

Annual re-growth of deer antler represents a unique example of complete organ regeneration. Because antler mesenchymal cells retain their embryonic capacity to develop into cartilage or bone, studying antler development provides a natural system to follow gene expression changes during mesenchymal differentiation toward chondrogenic/osteogenic lineage. To identify novel genes involved either in early events of mesenchymal cell specialization or in robust bone development, we have introduced a 3 K heterologous microarray set-up (deer cDNA versus mouse template). Fifteen genes were differentially expressed; genes for housekeeping, regulatory functions (components of different signaling pathways, including FGF, TGFbeta, Wnt), and genes encoding members of the Polycomb group were represented. Expression dynamics for genes are visualized by an expression logo. The expression profile of the gene C21orf70 of unknown function is described along with the effects when over-expressed; furthermore the nuclear localization of the cognate protein is shown. In this report, we demonstrate the particular advantage of the velvet antler model in bone research for: (1) identification of mesenchymal and precartilaginous genes and (2) targeting genes upregulated in robust cartilage development.

Ollier disease

Enchondromas are common intraosseous, usually benign cartilaginous tumors, that develop in close proximity to growth plate cartilage. When multiple enchondromas are present, the condition is called enchondromatosis also known as Ollier disease (WHO terminology). The estimated prevalence of Ollier disease is 1/100,000. Clinical manifestations often appear in the first decade of life. Ollier disease is characterized by an asymmetric distribution of cartilage lesions and these can be extremely variable (in terms of size, number, location, evolution of enchondromas, age of onset and of diagnosis, requirement for surgery). Clinical problems caused by enchondromas include skeletal deformities, limb-length discrepancy, and the potential risk for malignant change to chondrosarcoma. The condition in which multiple enchondromatosis is associated with soft tissue hemangiomas is known as Maffucci syndrome. Until now both Ollier disease and Maffucci syndrome have only occurred in isolated patients and not familial. It remains uncertain whether the disorder is caused by a single gene defect or by combinations of (germ-line and/or somatic) mutations. The diagnosis is based on clinical and conventional radiological evaluations. Histological analysis has a limited role and is mainly used if malignancy is suspected. There is no medical treatment for enchondromatosis. Surgery is indicated in case of complications (pathological fractures, growth defect, malignant transformation). The prognosis for Ollier disease is difficult to assess. As is generally the case, forms with an early onset appear more severe. Enchondromas in Ollier disease present a risk of malignant transformation of enchondromas into chondrosarcomas.

Comparison of allelic losses in chondroblastoma and primary chondrosarcoma of bone and correlation with fluorescence in situ hybridization analysis

Chondroblastoma (CBL) is a benign neoplasm of bone for which the genomic characteristics remain unclear. We compared the status of allelic losses of CBL with that seen in a set of chondrosarcomas (CS) to determine whether differences in their natural history and behavior are also reflected genetically. Eleven cases of CBL and 10 cases of CS of different grades were included. Tumors were subjected to microdissection and polymerase chain reaction using 17 markers located near genes on chromosomes 5, 9, 11, 13, 17, and 19. The selected chromosomes are known to be involved in several mesenchymal neoplasms. Fluorescence in situ hybridization was also performed on tumors displaying allelic losses, with dual-color probes for 9p, 17p, and 13q. Fractional allelic losses per gene ranged from 18.2% to 63.7% in CBLs and from 28.6% to 66.7% in CSs. Loss of heterozygosity (LOH) of 5q, 9p, 11p, 13q, and 19q occurred in both CBLs and CSs. Loss of heterozygosity of 17p (p53 locus) occurred in 7 of 11 CBLs and in only 1 case of recurrent CS. The pattern of allelic loss was similar in low-grade CSs and CBLs. Loci with LOH in both tumor types suggest possible involvement of the genes p53, RB1, CDKN2/p16, ERC, and XRCC in tumorigenesis. Overall correlation between LOH and fluorescence in situ hybridization results was 90% with 17p13, 80% with 9p, and 60% with 13q. The role of p53 in CBL is uncertain; however, given the benign behavior of this tumor, it is probably unrelated to tumor progression.

Double minutes, cytogenetic equivalents of gene amplification, in human neoplasia - a review

Double minutes are tiny spherical chromatin bodies of a few mega-base pairs of size which are found occasionally in hematopoietic neoplasia and more or less often in human solid tumors. They have been associated with worse prognosis and poor outcome of the malignancies where present. With the beginning era of molecular cytogenetics they could be defined as cytogenetic equivalents of amplified DNA sequences. The identification of involved chromosomal segments and their molecular nature led to the development of molecular genetic techniques for a rapid and reliable detection of prognostically important oncogene amplifications in human tumors and,as a consequence, to gene-targeted therapy.