ENO2 and neoplasm: Tumour markers have been explored extensively to distinguish between malignant and benign PEs, such as carcinoembryonic antigen (CEA), carbohydrate antigen 125 (CA125), carbohydrate antigen 19-9 (CA19-9), neuron-specific enolase (NSE) and cytokeratin 19 fragments (CYFRA21-1) [4].