去分化软骨肉瘤的诊断及治疗进展*

去分化软骨肉瘤（DDCS）约占所有软骨肉瘤的10% ，预后极差，5 年生存率不到10% 。好发于股骨、肱骨和骨盆。DDCS是软骨肉瘤中的一个独特类型。典型的特点是分化良好的软骨样成分和高度恶性的间充质细胞来源的肉瘤成分并存、毗邻。DDCS的诊断非常复杂，需要详细的影像学和病理学检查及准确的活检。DDCS去分化成分可以是骨肉瘤、恶性纤维组织细胞瘤，甚至是任何级别的未分化肉瘤成分。约1/3 的X 光片，1/3 的MR，一多半的CT扫描，DDCS表现为典型的“双态”征。最近利用微阵列- 比较基因组杂交技术，发现反复发生的5q14.2~q21.3，6q16~q25.3，9p24.2~q12和9p21.3。染色体缺失更多见于高度恶性的软骨肉瘤（3 级和DDCS），该差异具有统计学意义。9 号染色体的缺失是DDCS最常见的染色体缺失。早期研究发现DDCS的去分化成分有p53和p53杂合性的丢失现象，进一步研究发现同时伴随Rb基因杂合性的丢失。DDCS的两种成分可出现p16INK 4，FHIT和E-cadherin（上皮型钙黏附蛋白）甲基化的异常。手术切除包括合适足够的外科切缘或根治性的切除，是目前DDCS最主要的治疗手段。化疗效果目前仍然不确定。最近针对软骨肉瘤（包括DDCS）发现了一些新的药物靶标，有些已经进入临床Ⅱ期试验阶段，其中包括Apomab、Perifosine （哌立福新）、Dasatinib（达沙替尼）和多烯紫杉醇联合吉西他滨的联合化疗。同时几个Ⅰ期药物临床试验报告针对DDCS新的有效药物，如组蛋白去乙酰酶抑制剂和血管内皮生长因子反义寡合甘酸。DDCS患者预后极差，预后主要由DDCS中的去分化成分决定。因此，早期诊断、早手术对改善患者的预后非常关键。 

Progress in the Diagnosis and Treatment of Dedifferentiated Chondrosarcoma

Dedifferentiated chondrosarcoma(DDCS)comprises approximately 10%of all chondrosarcomas and has the worst outcome with a 5-year survival of 10%.The preferred localizations are the femur,humerus and pelvis.DDCS represents a special form of chondrosarcoma characterized by the presence of well-differentiated cartilaginous component in juxtaposition with malignant mesenchymal tumor of high-malignancy grade.The diagnosis of DDCS is highly complicated,requiring detailed radiological and histopathological evaluation as well as precise bioptic technique.The dedifferentiated component is typically a high-grade sarcoma(usually grade 3 or 4),which can be either an osteosarcoma,a malignant fibrous histiocytoma or an anaplastic spindle cell sarcoma.In approximately one-third of the radiographs,one-third of the MR images,and one-half of the CT scans, the tumors demonskates bimorphic features.Recently,array-based comparative genomic hybridization(array-CGH)studies have been performed on frozen chondrosarcoma(including DDCS)specimens.There is a statistically significant association between high-grade tumor(grade Ⅲ and dedifferent ated)and the recurrent genetic deletions at 5q14.2～q21.3,6q16～q25.3,9p24.2～q12,and 9p21.3.One of the most commonly deleted regions of DDCS involved chromosome 9.Earlier investigations of DDCS showed p53 mutation and p53-LOH in the anaplastic component.It is also accompanied by Rt-LOH.P161NK4 and E-cadherin promotor methylation were observed in the low grade chondroid compartment of DDCS.While p161NK4,FHIT,and E-cadherin were methylated in highly malignant osteosarcomatous compartment of the tumor.Surgical resection of the tumor within wide or radical margins is the most important treatment.The value of neoadjuvant or adjuvant therapy remain uncertain.Several new drug targets have been identified and phase Ⅱ studies are currently ongoing.Current phase Ⅱ trials open for DDCS patients used the following medicine:apomab(proapoptotic selective agonist of Ap02L/TRAIL death receptor),perifosine(serine/threonine kinase Akt inhibitor),dasatinib(multitargeted small-molecule tyrosine kinase inhibitor),and the combination of gemcitabine and docetaxel.More recently,several phase Ⅰ studies have reported incidental responses of DDCS to newer targeted agents,such as histone deacetylase and vascular endothelial growth factor antisense oligodeoxynucleotide.The prognosis for patients with DDCS remains poor. The poor prognosis of the DDCS is determined by nonchondroid high grade component caused by invasive growth and formation of metastases.Therefore,early diagnosis and prompt surgical treatment may improve the outcome.