Detection of Epstein‒Barr virus DNA methylation as tumor markers of nasopharyngeal carcinoma patients in saliva, oropharyngeal swab, oral swab, and mouthwash

Abstract

Saliva biopsy of nasopharyngeal carcinoma (NPC) has been developed in our latest study, indicating the application of oral sampling in NPC detection. Further exploration of the potential for self-sampling from the oral cavity is necessary. A total of 907 various samples from oral cavity, including saliva (n = 262), oropharyngeal swabs (n = 250), oral swabs (n = 210), and mouthwash (n = 185), were collected. Epstein‒Barr virus (EBV) DNA methylation at the 12,420 bp CpG site in EBV genome from the repeat-copy W promoter (Wp) region and at the 11,029 bp CpG site in the single-copy C promoter (Cp) region were simultaneously detected in these samples. A significant increase in EBV methylation, no matter at Wp or Cp region, was found in all types of samples from NPC patients. However, EBV DNA methylation in saliva and oropharyngeal swab showed a better diagnostic performance in detecting NPC. The combination of these two sample types and two markers could help to improve the detection of NPC. Our study further explored the optimal self-sampling methods and detection target in the detection of NPC and may facilitate the application of EBV DNA methylation detection in a home-based large-scale screening of NPC.

Keywords: Epstein‒Barr virus DNA methylation; nasopharyngeal carcinoma; oral swab; oropharyngeal swab; saliva.

FIGURE 1

Epstein‒Barr virus (EBV) load and C promoter (Cp) and W promoter (Wp) methylation levels in saliva, oropharyngeal swab, oral swab, and mouthwash samples. The methylation levels of Cp (B) and Wp (C) all had a significant increase in nasopharyngeal carcinoma (NPC) group compared to controls in all these samples.

FIGURE 2

Epstein‒Barr virus (EBV) DNA load and EBV DNA methylation in paired saliva and oropharyngeal swab samples from nasopharyngeal carcinoma (NPC) patients and controls. (A) Comparison of EBV DNA load in paired saliva and oropharyngeal swab samples. The methylation levels of C promoter (Cp) region (B) and W promoter (Wp) region (C) in paired saliva and oropharyngeal swab samples.