Methylation in Nasopharyngeal Swabs: A Potential Minimally Invasive Biomarker for the Early Detection of Nasopharyngeal Carcinoma.

Nasopharyngeal carcinoma (NPC) is highly prevalent in Southeast Asia, and an unfavorable outcome is usually attributed to advanced stage NPC. Current methods for the early diagnosis of NPC have limitations in clinical practice. The aim of this study was to investigate the diagnostic ability of methylation for NPC. A quantitative methylation-sensitive PCR (qMS-PCR) assay was developed to measure the methylation status and levels of in nasopharyngeal tissues and paired swabs from patients with NPC, chronic nasopharyngitis, and healthy donors. Methylated was detected in 92% (23/25) of NPC tissues and 25% (4/16) of nasopharyngitis controls ( < 0.05). High-frequency hypermethylation with decreased mRNA expression of in NPC was also identified. Further, methylation was identified in 90.5% (19/21) of NPC biopsies and 71.4% (15/21) of paired swabs, indicating a good concordance between the two sample types. In addition, methylated was found in 16 (72.7%) nasal swabs from 22 NPC patients, 2 of 19 (10.5%) nasopharyngitis, but not in any of the healthy controls ( < 0.01). The methylation score in nasal swabs of the NPC group was also significantly higher than that of non-NPC controls ( < 0.001). Moreover, receiver operating characteristic (ROC) curve analysis showed an area under the curve (AUC) of 0.882 of methylation tests to discriminate NPC from non-NPC subjects. Our study demonstrated that frequent methylation of was present in NPC. Its detection in nasopharyngeal swabs may provide a minimally invasive and informative method for identifying early NPC cases.