[Assessment of detection assays of Epstein-Barr viral Rta-IgG, VCA-IgA, EA-IgA and Epstein-Barr viral DNA at different clinical stages in the diagnosis of nasopharyngeal carcinoma].

OBJECTIVE: To evaluate the values of combined detection method of EB viral Rta-IgG, VCA-IgA, EA-IgA and EB viral DNA in the diagnosis of nasopharyngeal carcinoma (NPC). METHODS: Serum and plasma samples from 131 untreated NPC patients, 52 non-NPC patients with NPC-like symptoms and 148 healthy donors from January to December 2012 were collected. Immunoenzymatic staining was used to detect VCA-IgA and EA-IgA in sera. ELISA was performed to detect Rta-IgG antibody in sera and real-time fluorescent quantitative PCR for measuring EBV DNA in plasma. The clinical characteristics of 3 groups were compared. ROC curve and correlation analyses were performed to assess the detection assays for the diagnosis of NPC. RESULTS: The positive rates of EBV Rta-IgG, VCA-IgA, EA-IgA and EBV DNA in untreated NPC patient group were higher than those in other two groups. The differences were statistically significant (all P < 0.01). The differences of Rta-IgG antibody positive rates, EBV-DNA levels and EBV-DNA positive rates at different clinical stages were statistically significant (all P < 0.05). The positive rates of VCA-IgA and EA-IgA were not related with clinical stages (P > 0.05). Areas under ROC curve for Rta-IgG and EBV-DNA were 0.901 and 0.827 respectively. All four diagnostic assays demonstrated excellent efficiency. The sensitivity and specificity of individual assays were as follows: Rta-IgG: 77.9%, 92.5%; VCA-IgA 93.1%, 91.5%; EA-IgA: 74.8%, 99.5%; EBV-DNA 64.9%, 97.0%. The sensitivity and specificity of combined assays were 97.7% and 83.5% respectively. CONCLUSION: Combined detection method of EB viral Rta-IgG, VCA-IgA, EA-IgA and EB viral DNA are efficient for the diagnosis of NPC.