A promising predictive biomarker combined EBV NDA with PNI for nasopharyngeal carcinoma in nonendemic area of China.

In endemic areas, EBV DNA is used to guide diagnosis, detect recurrence and distant metastasis of NPC. Until now, the importance of EBV DNA in the prediction of NPC has received little attention in non-endemic regions. To explore the prognostic value of EBV DNA alone or in combination with PNI in NPC patients from a non-endemic area of China. In this retrospective study, 493 NPC patients were enrolled. Clinical pathologic data, pre-treatment plasma EBV DNA, and laboratory tests were all performed. A standard anticancer treatment was prescribed, and follow up data were collected. EBV DNA was found to be positively related to clinical stage (r = 0.357, P < 0.001), T stage (r = 0.193, P < 0.001), N stage (r = 0.281, P < 0.001), and M stage (r = 0.215, P < 0.001). The difference in EBV DNA loads between clinical stage, T, N and M stage was statistically significant (P < 0.001). In this study, the best cutoff value for EBV-DNA to distinguish the prognosis of NPC was 262.7 copies/ml. The 5-year OS of patients in the EBV-DNA ≤ 262.7 copies/ml group and EBV-DNA > 262.7 copies/ml group was 88% and 65.3%, respectively (P < 0.001). EBV-DNA and PNI were found to be independent prognostic factors for OS in multivariate analysis (P < 0.05). EBV-DNA was independent prognostic factors for PFS. In predicting NPC patients OS, the novel combination marker of EBV DNA and PNI outperformed TNM staging (AUC: 0.709 vs. 0.675). In addition, the difference between EBV + PNI and EBV + TNM was not statistically significant for OS or PFS (P > 0.05). This novel combination biomarker was a promising biomarker for predicting NPC survival and may one day guide treatment option.

Clinical relevance of plasma EBV DNA as a biomarker for nasopharyngeal carcinoma in non-endemic areas: A multicenter study in southwestern China.

BACKGROUND: Numerous clinical studies have validated plasma EBV DNA as a reliable biomarker for nasopharyngeal carcinoma (NPC) screening, tumor load monitoring, and prognosis prediction in endemic regions. However, the clinical relevance of plasma EBV DNA as a biomarker for NPC in non-endemic areas is still unclear. METHOD: The pretreatment plasma EBV DNA of 1405 newly diagnosed NPC patients from three major regional hospitals in non-endemic areas were analyzed retrospectively. The medical records of 244 age- and gender-matched healthy individuals were reviewed. EBV DNA was detected using Polymerase Chain Reaction (PCR). Based on the baseline of 400 and 0 copies/mL, the distribution characteristics of the pretreatment EBV DNA load in different clinical stages and geographic regions were analyzed. The diagnostic value of pretreatment plasma EBV DNA for NPC with two baselines was evaluated using the ROC curve. RESULTS: NPC patients had a significantly higher pretreatment EBV DNA level than healthy controls (P＜0.001). Pretreatment EBV DNA was closely associated with clinical and TNM stages in non-endemic areas, as it was in endemic areas. However, when 400 copies/mL set as the detection baseline, the sensitivity and specificity for NPC diagnosis were 40.8 % and 100 %, respectively (AUC = 0.704, cut off = 200.5 copies/mL). This sensitivity was lower than that reported in endemic regions (41.5 % - 97.1 %). Lower sensitivity may result in false negatives, missing diagnoses during NPC screening. Further investigation revealed that 39.7 % (558/1405) of NPC patients had detectable EBV DNA and S amplification curves. Optimizing the detection limit to 0 copies/mL, the sensitivity could be improved to 80.5 % (AUC = 0.901). CONCLUSIONS: In non-endemic areas, the clinical significance of plasma EBV DNA as a biomarker for NPC was restricted due to the low detection limit of 400 copies/mL. More efficient nucleic acid extraction and detection methods are needed to optimize the detection limit and increase the clinical application of plasma EBV DNA for NPC.

Experimental Research on Enhanced Oil Recovery Methods for Gas Injection of Fractured Reservoirs Based on Microfluidic Chips.

Gas injection is an effective method to enhance oil recovery of low-permeability and tight reservoirs, while the complicated fractures distributed in the formation have a noticeable effect on the performance of gas injection. In this study, three methods of gas injection were employed to conduct microfluidic experiments using micromodels simulating fractured reservoirs. The sweep efficiency and oil displacement efficiency of pores and throats, fractures, and the whole region were measured respectively to evaluate the oil displacement effects of the different gas injection methods. Moreover, the microscopic displacement process and the morphology of residual oil in porous media were analyzed to investigate the behavior of gas activated oil. The experimental results show that there are three stages of gas displacing oil: the oil in fractures was displaced first, then the oil in the pores and throats around the fracture was displaced, and finally the gas channeling occurred in fractures. Moreover, the sweep efficiency and oil displacement efficiency showed a tendency of increasing fast first and then reaching a steady state. Simultaneous injection of gas and water showed an optimal enhanced oil recovery effect among these three injection methods. Gas can invade deep throats, and those are difficult for water to sweep. However, the higher viscosity of water endowed it a smaller mobility than gas. And, the channeling in the two-phase mixing region was inhibited more obviously. The overall sweep efficiency and oil displacement efficiency increased about 18.4% and 13.4%, respectively.