Prognostic Significance of Chaperonin-Containing Tailless Complex Polypeptide 6A (CCT6A) in Ewing Sarcoma.

BACKGROUND: Chaperonin-Containing Tailless complex polypeptide 6A (CCT6A) is considered one of the biomarkers that play a role in cancer initiation, progression and resistance to body defenses and to anti-cancer drugs. Its exact prognostic role in Ewing sarcoma (ES) remains uncertain. The aim of this study is to assess immunohistochemical (IHC) expression of CCT6A in ES, and to assess the relation of its expression to different clinicopathological parameters and evaluate its prognostic significance in ES cases. METHODS: This retrospective cohort study included 35 cases diagnosed as ES at the Oncology Center of Mansoura University (OCMU), Faculty of Medicine, Egypt. Clinicopathological and survival data were collected. IHC for CCT6A was performed and correlated with clinicopathological parameters and patients' prognosis. RESULTS: High IHC expression of CCT6A was found in 28 cases out of the studied 35 ES cases (80%), while 7 cases only (20%) showed low CCT6A expression. High CCT6A expression showed significant association with tumor size ≥8 cm (P= 0.01), treatment with adjuvant radiotherapy either for local control, infiltrated surgical margins or poor histopathological response to chemotherapy (P= 0.01), poor histopathological response to chemotherapy (P= 0.02), and HUVOS grades I and II (P= 0.01). High CCT6A expression was found to be a predictor of shorter overall survival and was an independent poor predictive factor by multivariate analysis (P= 0.03). CONCLUSION: High CCT6A expression in ES associates with large tumor size, treatment with adjuvant radiotherapy for aforementioned indications, poor histopathological response to chemotherapy, and HUVOS grades I and II. Its high expression also independently predicts poor overall survival in ES patients. It may be used as a useful biomarker to predict prognosis of ES.