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The recent progress of the biology of the locally aggressive sarcomas of soft tissues and related connective tissue tumors enabled to reclassify molecular and histological entities of the disease. Six subgroups of sarcomas are identified with specific molecular alterations, the targeted treatments of which are the object of this article: 1) sarcomas with specific translocations with fusion oncogenes (DFSP, PVNS); 2) sarcomas with tyrosine kinase mutations (KIT in GIST); 3) tumors with deletion of tumor suppressor genes (TSC in the PEComes, NF1 involved in type 1 neurofibromatosis; 4) sarcomas with MDM2/CDK4 amplification in the 12q13-15 amplicon, i.e. well differentiated or dedifferentiated liposarcomas; 5) sarcomas with complex genetics present more unrefined genetic changes (leiomyosarcomas, osteosarcomas). On top these 5 groups, desmoids tumors characterized by alterations of the Wnt, beta catenin, APC, and giant cell tumors of the bone, in which RANK/RANKL operates a complex interaction between the cellular stroma and giant tumor cells. The identification of these abnormal ways of road marking to licence the development of effective targeted therapeutic agents against certain rare histological connective subcategories of sarcomas and tumors with local aggressiveness, in particular DFSP, PVNS, GCST, PEComes, endometrial stromal sarcomas, Ewing sarcomas, etc. Imatinib is used in the treatment of DFSP, characterized by a translocation of the gene PDGF, or in pigmented villonodular synovitis (PVNS), a tumor of soft part also locally aggressive, caused by an abnormality of the gene coding for the M-CSF. Several clinical trials of phase I and II trials demonstrated the antitumor activity of anti-IGF1R antibodies in Ewing, whose fusion gene downregulates IGFBP3. Inhibitors of MDM2 are in the course of clinical evaluation in liposarcomas. Inhibitors of mTOR (sirolimus, temsirolimus) demonstrated an antitumoral activity in the PEComas. The molecular characterization of sarcomas allowed to develop therapeutic targeted to correct the responsible abnormalities. Translational research is and will be an essential tool for the development of new treatments and the identification of the mechanisms of answer and resistance set up by these tumors.

Sarcomas comprise a heterogeneous group of mesenchymal neoplasms. They can be grouped into 3 general categories, soft tissue sarcoma, visceral and primary bone sarcoma, which have different staging and treatment approaches. Soft tissue sarcomas are typically classified on the basis of genetic alterations and light-microscopic examination of hematoxylin-eosin-stained tissue, in which recognizable morphological characteristics of normal tissues are identified. Sarcomas are further characterized by histologic grade. The 3 most important prognostic variables are grade, size, and location of the primary tumor. This review includes a discussion of both soft tissue sarcomas (unclassified sarcoma, liposarcoma, leiomyosarcoma, synovial sarcoma, dermatofibrosarcoma protuberans, angiosarcoma, Kaposi sarcoma, gastrointestinal stromal tumor, rhabdomyosarcoma, ...) and primary bone sarcomas (osteosarcoma, Ewing sarcoma and chondrosarcoma). The approach to a patient with a sarcoma begins with a biopsy that obtains adequate tissue for diagnosis without interfering with subsequent optimal definitive surgery. Subsequent treatment depends on the specific type of sarcoma. Due to the absence of clear knowledge for incidence rate, we conducted in 2005 and 2006 an exhaustive analysis of all diagnosed cases in the Rhône-Alpes region. Because sarcomas are relatively uncommon yet comprise a wide variety of different entities, second opinion was systematically performed for all included cases.

Recent progress made in the field of sarcoma biology has shed new light on the pathophysiology of these numerous but rare diseases. Soft tissue sarcomas can be divided into 6 sub-types based on the underlying molecular biology of the disease: 1) translocation leading to fusion proteins involving transcription factors or growth factors (Ewing sarcoma, myxoid liposarcoma, dermatofibrosarcoma protuberans); 2) tyrosine kinase receptor mutations (gastrointestinal stromal tumors); 3) tumor-suppressor gene deletion (type 1 neurofibromatosis, rhabdoid tumors); 4) genetic alteration such as amplification of chromosomal regions (well differentiated/dedifferentiated liposarcoma); 5) sarcomas with more complex genetic alterations (leiomyosarcoma) and 6) abnormalities involving the cell-adhesion pathways (aggressive fibromatosis). Together with the current development of numerous targeted therapies, these recent progress are the basis of tomorrow's personalised medicine for patients with soft tissue sarcoma.

Imatinib mesylate (Gleevec, Glivec, Novartis, Basel, Switzerland) is a small molecule inhibitor of the tyrosine kinase c-abl, c-kit and the platelet derived growth factor receptor (PDGFR). Imatinib was developed for the treatment of chronic myeloid leukaemia (CML) but was approved both in Europe and the US fro the treatment of CML and gastrointestinal stromal tumors (GIST). Given its activity against both c-kit and PDGFR kinases and its remarkable safety profile, imatinib has been 'tried' in several solid tumors; results however have often been deceiving. We review the current data regarding the activity of imatinib in solid tumors, including GIST.