| Background and Objective With the development of molecular,many indexes for detecting Epstein-Barr virus(EBV) have been developed. To investigate kinetics of Epstein-Barr virus(EBV) DNA in plasma of Nasopharyngeal Carcinoma(NPC) patients during treatment, and to evaluate its baseline value in the monitoring of NPC. With the development of molecular biology in recent years, Nasopharyngeal carcinoma(NPC)is closely related to Epstein-Barr viru(sEBV)infection. Recently, it was reported that EBV-DNA could be detected in the plasma or serum of NPC patients,peripheral blood EBV-DNA in patients with NPC can be detected with real-time PCR. But the clinical significance of EBV-DNA concentration for monitoring of tumor recurrence and metastasis in NPC patients before and after chemotherapy has not been reported. This study was designed to quantitatively analyze the plasma EBV-DNA concentration in patients with recurrent and metastatic Nasopharyngeal Carcinoma before and after chemotherapy, and to evaluate its application for monitoring of efficacy and prognosis.Methods 66 plasma samples were obtained from 33 patients who were histologically confirmed as NPC and referred to the Department 2 of chemotherapy in Guangxi Medical University affiliated tumor hospital between May 2008 and February 2010. Among them, 33 patients offered double samples of before chemotherapy and after chemotherapy plasma. As controls, 11 plasma samples of no-npc tumor patients were collected. EBV-DNA levels in plasma were detected in different patients including 33 patients with evidence of tumor recurrence or distant metastasis and 11 non-npc tumor patients,the quantity of plasma EBV-DNA was detected by using fluorescent quantitative PCR method in the DA7600 sequence Detector.Results 1.Plasma blood EBV-DNA in patients with NPC can be detected with real-time PCR. A high plasma EBV-DNA level could be detected in patients chemotherapy with recurrence or distant metastasis Nasopharyngeal Carcinoma before and after chemotherapy.A high plasma EBV-DNA level could be detected in 81.8%(27/33) patients before chemotherapy with recurrence or distant metastasis Nasopharyngeal Carcinoma, the median concentration was 4900 copies/m(linterquartile range:3075～54900), A high plasma EBV-DNA level could be detected in 51.5%(17/33) patients after chemotherapy with recurrence or distant metastasis Nasopharyngeal Carcinoma, the median concentration was 520copies/ml,(interquartile range:0～33695)whereas only 9.1% (1/11) patients with non-npc tumor could be detected a high lever, the median concentration was 0copies/ml.There was significant difference between EBV-DNA levels of NPC before Chemotherapy and after Chemotherapy and no-npc tumor patients (P<0.05). There was significant difference positive rate between NPC before Chemotherapy and after Chemotherapy and no-npc tumor patients (P < 0.01). EBV-DNA levels and positive rate of NPC before Chemotherapy were higher than EBV-DNA levels and positive rate of NPC after Chemotherapy and no-npc tumor patients. There was significant difference between plasma EBV-DNA positive rate in NPC after Chemotherapy and no-npc tumor patients(P=0.034).2. A high plasma EBV DNA level could be detected in 72.7%(16/22) patients with benefit before chemotherapy, them median concentration was 3110copies/ml, whereas only 31.8% (7/22) patients with benefit after chemotherapy could be detected a high level the median concentration was 0copies/ml. There was significant difference between plasma EBV-DNA positive rate and EBV-DNA levels in NPC patients with benefit before chemotherapy and after Chemotherapy(P=0.007, 0.009).Subgroup of clinical benefit group analysis showed that a high plasma EBV-DNA level could be detected in 70.6% (12/17) patients with availability group before chemotherapy, them median concentration was 3090copies/ml, whereas only 23.5%(4/17) patients with benefit after chemotherapy could be detected a high lever, the median concentration was 0copies/ml. There was significant difference between plasma EBV-DNA positive rate and EBV-DNA levels in NPC patients with benefit before chemotherapy and after Chemotherapy (P=0.015, 0.005).Subgroup of Stable condition group analysis showed that a high plasma EBV-DNA level could be detected in 80.0%(4/5) patients with availability group before chemotherapy, them median concentration was 5260copies/ml, whereas only 60.0%(3/5) patients with benefit after chemotherapy could be detected a high lever, the median concentration was 2530copies/ml. There was no significant difference between plasma EBV-DNA positive rate and EBV-DNA levels in NPC patients with Stable condition before chemotherapy and after Chemotherapy (P=1.000, 0.345).A high plasma EBV-DNA level could be detected in 100.0% (11/11)patients with progress disease before chemotherapy, them median concentration was 37800copies/ml, A high plasma EBV-DNA level could be detected in 90.9%(10/11) patients with Progress disease after chemotherapy, them median concentration was 60200copies/ml, There was no significant difference between plasma EBV-DNA positive rate and EBV-DNA levels in NPC patients with progress disease before chemotherapy and after Chemotherapy(P>0. 05).3. Kaplan-Meier survival analysis showed that there are total 33 cases with recurrence or distant metastasis NPC patients, the average progression-free survival for positive and negative plasma EBV-DNA expression group before chemotherapy and after Chemotherapy are 7.6 months,6.0 months,14.2 months and 11.9 months respectively.The survival difference was significant between the positive and negative plasma EBV-DNA expression groups in recurrence or distant metastasis NPC patients before chemotherapy and after Chemotherapy(P =0.044, 0.002).Negative plasma EBV-DNA expression group have long survival than positive plasma EBV-DNA expression group in recurrence or distant metastasis NPC patients before chemotherapy and after Chemotherapy.Conclusion Plasma EBV-DNA level change may be a valuable index for application for monitoring of efficacy and prognosis in Recurrent and Metastatic nasopharyngeal carcinoma patients before and after chemotherapy, Our results suggest that further investigation is warranted.. 1. Plasma EBV-DNA level change may use for detecting effects of treatment in Recurrent and Metastatic NPC. Plasma EBV-DNA concentrations decline rapidly to the undetectable value in most effective cases after the beginning of chemotherapy.2. Plasma EBV-DNA level may be an influence factor for application for monitoring of prognosis in Recurrent and Metastatic nasopharyngeal carcinoma patients before and after chemotherapy.
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