Evaluation of Epstein–Barr virus DNA methylation and load in saliva in the management of individuals at high risk of nasopharyngeal carcinoma

BACKGROUND: The current Epstein–Barr virus (EBV) antibody-based screening strategy for nasopharyngeal carcinoma (NPC) has been used for years. However, its low positive predictive value (PPV) often leads to unnecessary diagnostic procedures. Thus, further triage strategies are needed. METHODS: Saliva EBV DNA methylation and viral load were explored as noninvasive triage tools for NPC detection in this study. Saliva samples were collected from 621 NPC patients and 642 healthy controls recruited in Guangdong Province, China, between 2011 and 2014. The EBV DNA methylation and viral load were measured by real-time PCR, and the diagnostic performance was assessed for each biomarker individually and in combination using a logistic regression model. A simulation model was developed to evaluate the efficiency of a stepwise screening strategy integrating serum EBV antibody testing and saliva EBV DNA testing. RESULTS: Compared with the controls, EBV load was decreased while DNA methylation was increased in the saliva of NPC patients (both P < 0.0001). The area under the curve (AUC) values for saliva EBV DNA methylation and viral load in distinguishing patients from controls were 0.865 (95% CI: 0.835–0.894) and 0.594 (95% CI: 0.552–0.637), respectively. Combining both markers increased the AUC to 0.908 (95% CI: 0.868–0.947). In the high-risk group based on serum EBV antibody testing, the combination of assessments of saliva EBV DNA methylation and viral load yielded an AUC of 0.969 (95% CI: 0.945–0.993). In a modeled screening program, a stepwise approach using serum EBV antibodies followed by saliva testing for EBV DNA methylation and viral load reduced the number of endoscopic examinations needed to identify one patient with NPC by approximately 60%, increasing the PPVs to 2.40–2.63 times across populations with NPC incidence rates ranging from 10 to 200 per 100,000, compared with EBV serology-only screening. CONCLUSIONS: Saliva testing for EBV DNA methylation and viral load shows potential as a triage tool following serum EBV antibody-based screening. The feasibility of home-based self-sampling further increases its utility in the management of individuals at high risk of NPC. CLINICAL TRIAL NUMBER: Not applicable.