Evaluation of circulating EBV microRNA BART2-5p in facilitating early detection and screening of nasopharyngeal carcinoma

Nasopharyngeal carcinoma is an Epstein-Barr Virus (EBV) associated malignancy which is highly prevalent in Southeast Asia. EBV-related antibodies have been widely used as screening markers for early nasopharyngeal carcinoma (NPC) detection. However, due to its low positive predictive rate, it is essential to develop new biomarkers to facilitate NPC early diagnosis or triage EBV serological high-risk individuals to improve the chance of NPC early detection. BART microRNAs, which are encoded by BamHI region of EBV, were reported to be abundant in NPC and have potential value in early diagnosis of NPC. Here, we quantified circulating level of 17 BART microRNAs in discovery stage based on previous microarray and sequencing data and, in particular, BART 2-5p, the sole candidate whose area under curve (AUC) was higher than 0.8, has been chosen for further study. In validation stage, the sensitivity, specificity and AUC of BART 2-5p was 93.9%, 89.8%, 0.972 (95%CI: 0.954-0.989), respectively, in Cohort 1 constituted by NPC patients and controls from Hong Kong. For validation Cohort 2 consisting of patients and controls from Guangzhou, the sensitivity, specificity and AUC was 94.2%, 83.5%, 0.959 (95%CI: 0.939-0.980), respectively. To evaluate its ability to distinguish preclinical NPC patients, we established a nested case-control study with serum samples prospectively collected from 22 NPC patients prior to their clinical diagnosis and 88 matched healthy high-risk controls in a screening trial. The sensitivity and specificity were 90.9% and 54.5%. Collectively, EBV microRNA BART2-5p may be a valuable biomarker for early detection of NPC.