[A MOLECULAR APPROACH TO DIAGNOSIS AND TREATMENT OF PEDIATRIC SOFT TISSUE SARCOMA FROM "E PLURIBUS UNUM" TO "EX UNO PLURES" AND BACK].

Soft tissue sarcoma is a heterogeneous group of mesenchymal (fat, muscle, cartilage and blood vessel) tumors. It collectively comprises 1% of adult malignancies, and 7% of pediatric malignancies and according to the last WHO classification, contains over 50 histologic diagnoses. Due to its relatively infrequent occurrence, diversity of sub-types and high rates of inter-observer disagreement regarding the histological sub-type, the approach to both basic and clinical research, and, accordingly, treatment has traditionally been "one size fits all". All soft tissue sarcoma sub-types were merged in clinical studies, and assigned standard treatment. Although this approach made large scale clinical studies possible, it hindered our understanding of the treatment effect in specific sub-types of soft tissue sarcoma (since small sub-groups were diluted in the general study population), and did not promote our understanding of sub-type specific oncogenesis. In recent decades, as molecular understanding of oncogenesis advances, it is used increasingly as an adjunct to histology and immunohistochemistry for diagnostic as well as therapeutic purposes. As the diagnosis of the soft tissue sarcoma sub-type becomes more accurate and unambiguous, we can efficiently focus research (both basic and clinical) on sub-type specific oncogenesis, and (consequently) allow sub-type specific treatment.