Expression of DNA Repair Genes in Ewing Sarcoma.

Background/Aim: Ewing sarcoma is an aggressive mesenchymal malignancy commonly affecting children and young adolescents. The molecular basis of this neoplasia is well reported with the formation of the EWSR1/FLI1 fusion gene being the most common genetic finding. However, this fusion gene has not been targeted therapeutically nor is being used as a prognostic marker. Its relevance regarding the molecular steps leading to Ewing sarcoma genesis are yet to be defined. The generation of the oncogenic EWSR1/FLI1 fusion gene, can be attributed to the simultaneous introduction of two DNA double-strand breaks (DSBs). The scope of this study is to detect any association between DNA repair deficiency and the clinicopathological aspects of Ewing's sarcoma disease. Patients and Methods: We have conducted an expression analysis of 35 patients diagnosed with Ewing sarcoma concerning the genes involved in non-homologous end joining (NHEJ) and homologous recombination (HR) repair pathways. We have analyzed the expression levels of 6 genes involved in NHEJ (XRCC4, XRCC5, XRCC6, POLλ, POLµ) and 9 genes involved in HR (RAD51, RAD52, RAD54, BRCA1, BRCA2, FANCC, FANCD, DNTM1, BRIT1) using real time PCR. Age, sex, location of primary tumor, tumor size, KI67, mitotic count, invasion of adjacent tissues and treatment were the clinicopathological parameters included in the statistical analysis. Results: Our results show that both these DNA repair pathways are deregulated in Ewing sarcoma. In addition, low expression of the xrcc4 gene has been associated with better overall survival probability (p=0.032). Conclusion: Our results, even though retrospective and in a small number of patients, highlight the importance of DSBs repair and propose a potential therapeutic target for this type of sarcoma.

A Case Series of BCOR Sarcomas With a New Splice Variant of BCOR/CCNB3 Fusion Gene.

BACKGROUND/AIM: Undifferentiated round cell sarcomas are a heterogeneous group of sarcomas. Identification of BCOR alterations, such as BCOR/CCNB3 and BCOR/MAML3 fusion genes and BCOR ITD has recently contributed in the precise diagnosis of these neoplasms, defining a new entity of the current classification of soft tissue and bone sarcomas. BCOR sarcomas share both morphological and genetic characteristics distinct from Ewing sarcomas. The scope of our study was to retrospectively identify BCOR sarcomas and find the correlations with the clinical outcome of these patients. PATIENTS AND METHODS: Histopathology and immunohistochemistry of pediatric tumor samples were combined with molecular testing (PCR) and fluorescent in situ hybridization to find BCOR sarcomas. RESULTS: We, herein, present our experience with BCOR sarcomas in a referral center of Greece. Moreover, we report in one case the detection of a variant BCOR/CCNB3 fusion not previously described. CONCLUSION: We are the first to report a splice variant of BCOR/CCNB3 which reveals the central position of BCOR in the oncogenesis of these tumors, furthermore we highlight the importance of molecular diagnostics in Ewing-like sarcomas and discuss the current treatment options for this rare entity.

Ewing's sarcoma of the cervix: A case report of an unusual diagnosis in pregnancy treated with surgery, adjuvant VIDE and radiotherapy.

Ewing's sarcoma of the cervix is a rare entity and presents with considerable challenges in diagnosis and therapy. Herein, we report a case of a cervical Ewing's sarcoma presenting with FIGO stage Ib, diagnosed during the first trimester of the patient's pregnancy. Imaging with CT scans, MRI of her abdomen and PET-CT verified the locoregional extension of the tumor. The diagnosis was confirmed by immunohistochemistry and molecular analysis. Fluorescence in situ hybridization and RT-PCR detected the pathognomonic EWS/FLI fusion gene. Favorable prognostic factors regarding the stage, clinocopathological and molecular characteristics of the tumor are also described. Due to the rarity of the disease, at present, there is no universal consensus on the optimal therapeutic approach. The literature has been reviewed and the therapeutic schemes and available clinical data have been discussed. The patient presented in this case report was treated aggressively with tri-modality therapy and underwent radical hysterectomy followed by adjuvant chemotherapy with Vincristine-Ifosfamide-Doxorubicin-Etoposide and radiotherapy. The patient remains free of this disease 42 months following the diagnosis of her tumor.