Diagnostic and prognostic performance of circulating levels of the Epstein-Barr virus microRNAs BART 7-3p and BART 13-3p in nasopharyngeal carcinoma

Background Nasopharyngeal carcinoma (NPC) is closely associated with Epstein-Barr virus (EBV) infection. EBV BamHI A rightward transcripts (BART) encode microRNAs (EBV-miR-BARTs) abnormally highly expressed and play an essential role in NPC. Our previous study indicated that circulating EBV-miR-BARTs was potentially severed as a biomarker of NPC. This study aims to investigate the diagnostic and prognostic performance of miR-BART7-3p and miR-BART13-3p. Methods Plasma levels of EBV DNA, miR-BART7-3p, and miR-BART13-3p were examined by quantitative PCR in 483 treatment-naïve NPC patients and 243 controls without NPC. The prognostic performance was examined by comparing plasma levels with rates of distant metastasis during follow-up. Results Plasma EBV DNA was detected in 93.7% of NPC subjects vs. 8.6% of controls. The microRNAs BART7-3p and miR-BART13-3p were detected in 96.1% and 97.9% of NPC subjects vs. 3.39% and 3.3% of controls. The area under the receiver operating characteristic curve for diagnosing NPC was 0.926 for EBV DNA, 0.964 for miR-BART7-3p, 0.973 for miR-BART13-3p, and 0.997 for all three indices. Among 465 NPC patients without distant metastasis, the above-median miR-BART7-3p and EBV-DNA were independent risk for shorter distant metastasis-free survival (DMFS) (HR=2.94, 95%CI: 1.44-5.97, p=0.003; HR=2.27, 95%CI:1.26-4.10, p=0.006) in multivariate Cox regression. In the 245 patients who received radiotherapy, EBV DNA, miR-BART7-3p, and miR-BART13-3p were detectable immediately afterward in, respectively, 28.6%, 17.6%, and 54.7% of patients. Four-year DMFS rate was lower in patients with detectable miR-BART7-3p (73.0% vs. 89.7%, p<0.001), miR-BART13-3p (61.4% vs. 90.0%, p<0.001), and EBV-DNA (82.7% vs. 89.5%, p=0.035) after radiotherapy. In multivariate Cox regression, detectable miR-BART7-3p and EBV-DNA were independent risks for shorter DMFS (HR=4.13, 95%CI: 1.89-9.01, p<0.001; HR = 2.14, 95%CI: 1.04-4.42, p=0.039). Four-years DMFS rate was 92.0% in subjects (n=156) with neither detectable miR-BART7-3p nor EBV-DNA after radiotherapy, 80.0% in subjects (n=65) with either detectable miR-BART7-3p or EBV-DNA after radiotherapy, and 52.9% in subjects (n=24) with both detectable miR-BART7-3p and EBV-DNA after radiotherapy (p<0.001). Conclusions Circulating levels of miR-BART7-3p and miR-BART13-3p show excellent diagnostic performance for NPC. The combination of plasma levels of miR-BART7-3p and EBV DNA at diagnosis and after radiotherapy may help stratify patients by risk of poor DMFS.