Detection of EWS/FLI-1 fusion in non-Ewing soft tissue tumors

OBJECTIVES EWS/FLI-1 fusion mainly appears in Ewing's sarcoma or the primitive neuroectodermal tumors and represents a genomic marker for these tumors. However, it can appear with lower frequency in other soft tissue tumors. The paper investigates the presence of EWS/FLI-1 fusion in clinically diagnosed sarcoma belonging to different non-Ewing connective tissue tumors in order to search for a possible new biomarker valuable for investigators. METHODOLOGY 20 patients with soft tissue tumors, who underwent surgery, were tested. Intra-operative samples of normal and tumor tissue were collected for histopathological diagnosis and genetics determinations. The patients' RNA from tumor and normal peritumoral tissue was extracted and EWS/FLI-1 fusion screened by quantitative real-time PCR. The relative expression of the fusion in the tumor sample was compared to the similar expression in normal tissue. RESULTS The amplification in the threshold zone was shown by 5 samples (25%): 2 clear cell sarcoma, 1 fibrosarcoma, 1 malignant tumor of nerve sheath, 1 metastatic adenocarcinoma. We differentiated between the unspecific amplification and concluded that these are weak positive results. CONCLUSIONS Genomic investigation may establish the tumor malignancy and its possible affiliation earlier than histopathology. It can support the screening of EWS/FLI-1 fusion in a larger variety of clinically diagnosed soft tissue tumors.