Antonie H. M. Taminiau

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.

EXT-mutation analysis and loss of heterozygosity in sporadic and hereditary osteochondromas and secondary chondrosarcomas

Osteochondromas occur as sporadic solitary lesions or as multiple lesions, characterizing the hereditary multiple exostoses syndrome (EXT). Approximately 15% of all chondrosarcomas arise within the cartilaginous cap of an osteochondroma. EXT is genetically heterogeneous, and two genes, EXT1 and EXT2, located on 8q24 and 11p11-p12, respectively, have been cloned. It is still unclear whether osteochondroma is a developmental disorder or a true neoplasm. Furthermore, it is unclear whether inactivation of both alleles of an EXT gene, according to the tumor-suppressor model, is required for osteochondroma development, or whether a single EXT germline mutation acts in a dominant negative way. We therefore studied loss of heterozygosity and DNA ploidy in eight sporadic and six hereditary osteochondromas. EXT1- and EXT2-mutation analysis was performed in a total of 34 sporadic and hereditary osteochondromas and secondary peripheral chondrosarcomas. We demonstrated osteochondroma to be a true neoplasm, since aneuploidy was found in 4 of 10 osteochondromas. Furthermore, LOH was almost exclusively found at the EXT1 locus in 5 of 14 osteochondromas. Four novel constitutional cDNA alterations were detected in exon 1 of EXT1. Two patients with multiple osteochondromas demonstrated a germline mutation combined with loss of the remaining wild-type allele in three osteochondromas, indicating that, in cartilaginous cells of the growth plate, inactivation of both copies of the EXT1 gene is required for osteochondroma formation in hereditary cases. In contrast, no somatic EXT1 cDNA alterations were found in sporadic osteochondromas. No mutations were found in the EXT2 gene.

Diffusion-weighted MRI in the characterization of soft-tissue tumors

To explore the potential of perfusion‐corrected diffusion‐weighted magnetic resonance imaging (MRI) in characterizing soft‐tissue tumors.

Emerging pathways in the development of chondrosarcoma of bone and implications for targeted treatment

Chondrosarcoma is a malignant cartilage-forming tumour of bone, of which distinct clinicopathological subtypes are known. Conventional chondrosarcoma is notorious for its locally aggressive behaviour as well as for its resistance to chemotherapy and radiotherapy; so far surgery is the only effective therapeutic option. During the past 10 years, substantial new insights have been gained about molecular cell biology, molecular cytogenetics, and immunopathology, leading to better understanding of chondrosarcoma development at the molecular level, which will ultimately lead to better clinical understanding and possibly to the development of targeted treatment.

Adamantinoma of the long bones. A clinicopathological study of thirty-two patients with emphasis on histological subtype, precursor lesion, and biological behavior.

The records of thirty-two patients who had had an adamantinoma of the long bones were examined to investigate the relationship between the clinical presentation, the histological subtype, and the method of treatment, and the clinical result. All histological patterns of differentiation that are characteristic of adamantinoma were observed, including the basaloid, spindle-cell, tubular, squamous, and osteofibrous dysplasia-like subtypes. Follow-up data were available for twenty-eight (88 per cent) of the thirty-two patients. These patients were followed for a mean duration of 122 months (range, eleven months to twenty-nine years and two months). Nine patients (32 per cent), all of whom had been managed with an intralesional or marginal procedure, had a local recurrence of the tumor after a mean disease developed in three of the nine patients. In five other patients, metastasis developed without having been preceded by a local recurrence. Thus, the over-all rate of metastasis was 29 per cent (eight patients). The mean duration of survival for the patients who had metastasis was twelve years and eight months. Statistical analysis of various clinicopathological variables revealed intralesional or marginal excision to be the most significant risk factor for a local recurrence or metastasis (p < 0.001). Two patients who had had a presumed osteofibrous dysplasia-like adamantinoma, which contained few isolated keratin-positive epithelial cells within the stroma at the time of presentation, had a full-blown adamantinoma at the time of the local recurrence. Although the clinical course that was observed may be the result of a sampling error, it poses questions as to the regressive nature of osteofibrous dysplasia-like adamantinoma. On the basis of our findings and the data in the literature, we believe that an osteofibrous dysplasia-like adamantinoma may be a precursor lesion of the classic type of adamantinoma.

Loss of Heterozygosity and DNA Ploidy Point to a Diverging Genetic Mechanism in the Origin of Peripheral and Central Chondrosarcoma

Chondrosarcomas are malignant cartilaginous tumors arising centrally in bone (central chondrosarcoma), or secondarily within the cartilaginous cap of a hereditary or sporadic exostosis (peripheral chondrosarcoma). Loss of heterozygosity (LOH) was studied by microsatellite analysis at the loci harboring the EXT genes (implicated in hereditary multiple exostoses), the EXT‐like genes, and at 9p21, 13q14, 17p13, and chromosome 10. Nineteen of 20 peripheral chondrosarcomas showed LOH at all loci tested, while only 3 of 12 central chondrosarcomas exhibited LOH, restricted to 9p21, 10, 13q14, and 17p13. LOH at 9p21 did not appear to involve the CDKN2A gene, as assessed by SSCP analysis. DNA flow cytometry demonstrated a wide variation in the ploidy status in peripheral chondrosarcomas (DNA indexes, 0.56–2.01), whereas central chondrosarcomas were predominantly peridiploid. Near‐haploidy found in peripheral chondrosarcomas could explain part of the high LOH percentages. Ki‐67 immunohistochemistry suggested a higher proliferation rate in peripheral chondrosarcomas. Our results indicate that peripheral chondrosarcomas, arising secondarily to an exostosis, may obtain genetic alterations during malignant transformation, with subsequent genetic instability as demonstrated by a high percentage of LOH and a wide variation in ploidy status. In contrast, peridiploidy and a low percentage of LOH in central tumors suggest that a different oncogenic molecular mechanism may be operative. Genes Chromosomes Cancer 26:237–246, 1999.

The effect of local recurrence on survival in resected osteosarcoma

The aim of this study was to assess the effect of local recurrence on survival in primary osteosarcoma. 559 patients entered into two randomised trials of the European Osteosarcoma Intergroup who received surgery for primary operable high-grade osteosarcoma of the extremities were included in this analysis. Proportional hazards modelling techniques were used to assess the relative importance of sex, age, site, surgery performed and local recurrence. The last of these was considered as a time-dependent covariate. 42/559 (8%) patients had a local recurrence. In the multivariate analysis, local recurrence was found to greatly increase the risk of death (hazard ratio (HR)=5.10, 95% confidence interval (CI) 3.51-7.41). Site and surgery performed also had a significant influence within this model. Using the technique of landmark analysis, with the landmark time set at 18 months, local recurrence alone had a significant influence on survival (HR=4.60, 95% CI 2.80-7.57). Local recurrence is an indicator of poorer survival for patients with operable primary osteosarcoma.

Survival from high-grade localised extremity osteosarcoma: combined results and prognostic factors from three European Osteosarcoma Intergroup randomised controlled trials

BACKGROUND Neoadjuvant chemotherapy improves outcome in osteosarcoma. Determination of optimum regimens for survival, toxicity and prognostic factors requires randomised controlled trials to be conducted. PATIENTS AND METHODS Between 1983 and 2002, the European Osteosarcoma Intergroup recruited 1067 patients with localised extremity osteosarcoma to three randomised controlled trials. Standard treatment in each was doxorubicin 75 mg/m(2) and cisplatin 100 mg/m(2). Comparators were addition of methotrexate (BO02/80831), a multidrug regimen (BO03/80861) and a dose-intense schedule (BO06/80931). Standard survival analysis methods were used to identify prognostic factors, temporal and other influences on outcome. RESULTS Five- and 10-year survival were 56% (95% confidence interval 53% to 59%) and 52%, respectively (49% to 55%), with no difference between trials or treatment arms. Median follow-up was 9.4 years. Age range was 3-40 years (median 15). Limb salvage was achieved in 69%. Five hundred and thirty-three patients received the standard arm, 79% completing treatment. Good histological response to preoperative chemotherapy, distal tumour location (all sites other than proximal humerus/femur) and female gender were associated with improved survival. CONCLUSIONS Localised osteosarcoma will be cured in 50% of patients with cisplatin and doxorubicin. Large randomised trials can be conducted in this rare cancer. Failure to improve survival over 20 years argues for concerted collaborative international efforts to identify and rapidly test new treatments.

Kinome Profiling of Chondrosarcoma Reveals Src-Pathway Activity and Dasatinib as Option for Treatment

Chondrosarcomas are notorious for their resistance to conventional chemotherapy and radiotherapy, indicating there are no curative treatment possibilities for patients with inoperable or metastatic disease. We therefore explored the existence of molecular targets for systemic treatment of chondrosarcoma using kinome profiling. Peptide array was performed for four chondrosarcoma cell lines and nine primary chondrosarcoma cultures with GIST882, MSCs, and colorectal cancer cell lines as controls. Activity of kinases was verified using immunoblot, and active Src- and platelet-derived growth factor receptor (PDGFR) signaling were further explored using imatinib and dasatinib on chondrosarcoma in vitro. The AKT1/GSK3B pathway was clearly active in chondrosarcoma. In addition, the PDGFR pathway and the Src kinase family were active. PDGFR and Src kinases can be inhibited by imatinib and dasatinib, respectively. Although imatinib did not show any effect on chondrosarcoma cell cultures, dasatinib showed a decrease in cell viability at nanomolar concentrations in seven of nine chondrosarcoma cultures. However, inhibition of phosphorylated Src (Y419) was found both in responsive and nonresponsive cells. In conclusion, using kinome profiling, we found the Src pathway to be active in chondrosarcoma. Moreover, we showed in vitro that the inhibitor of the Src pathway, dasatinib, may provide a potential therapeutic benefit for chondrosarcoma patients who are not eligible for surgery.

Molecular genetic characterization of both components of a dedifferentiated chondrosarcoma, with implications for its histogenesis.

Dedifferentiated chondrosarcoma is defined as a high‐grade, anaplastic sarcoma adjacent to a low‐grade malignant cartilage‐forming tumour. Controversy remains as to whether the anaplastic and cartilaginous components are derived from a common precursor cell, or whether they represent separate genotypic lineages (collision tumour). Both components of a case of dedifferentiated chondrosarcoma were therefore separately investigated by loss of heterozygosity (LOH) analysis, comparative genomic hybridization (CGH), DNA flow cytometry, and p53 analysis. Both showed p53 overexpression and an identical somatic 6 bp deletion in exon 7 of p53. Combination of the CGH and LOH results revealed that both components had lost the same copy of chromosome 13. These results provide compelling evidence in this case for a common origin, instead of the ‘collision tumour’ theory. Certain genotypic alterations were not shared. The anaplastic component showed severe aneuploidy, LOH at additional loci, and amplification and deletion of several chromosome parts. In contrast, the cartilaginous component had lost chromosomes 5, 22, 17p and part of 16p and revealed an amplification of 17q. The LOH and CGH results further demonstrated that the two components had lost a different copy of chromosome 4. Thus, a substantial number of genetic alterations have occurred after the diversion of the two components, indicating that the separation of the two clones, derived from a single precursor, was a relatively early event in the histogenesis of this case of dedifferentiated chondrosarcoma. Copyright