Soft tissue sarcomas: From a morphological to a molecular biological approach.

Recently developed molecular genetic techniques have led to the elucidation of tumor-specific genomic alterations and thereby the reclassification of tumor entities of soft tissue sarcoma. A solitary fibrous tumor-mimicking tumor with the AHRR-NCOA2 gene has been isolated as angiofibroma of soft tissue. As for small round cell sarcomas, novel fusion genes such as CIC-DUX4 and BCOR-CCNB3 have been identified in these tumor groups. SMARCB1/INI1 deficient tumors with round cell morphology are also expected to be reclassified in three types, based on the combination of their morphology and genotype. The identification of the MDM2 gene amplification in pleomorphic sarcomas has extended the entity of dedifferentiated liposarcoma (DDLS). Our recent molecular investigations elucidated candidates for novel therapeutic strategies. Activation of the Akt-mTOR pathway was correlated with poor prognosis or tumor grade in spindle cell sarcomas including malignant peripheral nerve sheath tumor. In vitro and in vivo studies of transcription factor Forkhead Box M1 (FOXM1) demonstrated the close correlation between aggressive biological behavior or chemosensitivity and FOXM1 expression in synovial sarcoma, so far. Finally, in regard to the investigation of cancer-testis antigens, myxoid/round cell liposarcoma and synovial sarcoma showed frequent and high expression of PRAME and NY-ESO-1.