Changes in plasma EBV-DNA and immune status in patients with nasopharyngeal carcinoma after treatment with intensity-modulated radiotherapy

BACKGROUND: Previous studies reported the early diagnostic values of plasma Epstein-Barr virus (EBV)-DNA. The present study aimed to assess the relationship between the concentration of plasma EBV-DNA and the number of CD8(+)PD-1(+)(programmed cell death-1,PD-1) and regulatory T (Treg) cells in patients with nasopharyngeal carcinoma (NPC) who were treated with intensity-modulated radiotherapy (IMRT). METHODS: This study included 37 patients treated with IMRT. Peripheral blood samples were collected two times for each patient, before radiation therapy and 1 week after the treatment. Further, the numbers of CD4(+), Treg, CD8(+), and CD8(+)PD1(+) cells were determined by flow cytometry. RESULTS: The changes after IMRT were determined by comparing the numbers of neutrophils, lymphocytes, CD4(+), Treg, CD8(+), CD8(+)PD1(+) cells, and the concentration of plasma EBV-DNA between pretreatment and post-treatment groups. IMRT could reduce the expression level of PD-1 and the number of Treg cells. The concentration of plasma EBV-DNA and the expression level of CD8(+)PD-1(+) were closely associated with the occurrence and development of NPC. Thus, EBV-DNA can be used as an important marker for early diagnosis, and IMRT can strongly reduce the copies of EBV-DNA. CONCLUSIONS: This study showed that IMRT could reverse T-cell exhaustion and reduce the copies of EBV-DNA. In clinical practice, plasma EBV-DNA is a sensitive biomarker for diagnosis, prognosis, and evaluation of clinical efficacy.