Expression of EBV antibody EA-IgA, Rta-IgG and VCA-IgA and SA in serum and the implication of combined assay in nasopharyngeal carcinoma diagnosis.

Epstein-Barr virus (EBV) is an important non-invasive index for nasopharyngeal carcinoma. Serum sialic acid (SA) level was known to be related with tumor progression. Rta protein antibody IgG (Rta-IgG), early antigen antibody (EA-IgA) and viral capsid antibody (VCA-IgA) levels in serum can also be used to effectively monitor the progression of cancer. This study investigated serum level of SA, Rta-IgG, EA-IgA and VCA-IgA in nasopharyngeal cancer patients and the diagnostic value of combined assay. A total of 64 nasopharyngeal cancer patients were recruited, in parallel with 60 benign rhinitis and 60 healthy individuals. Serum SA, EA-IgA, Rta-IgG and VCA-IgA levels were measured by enzyme-linked immunosorbent assay (ELISA). The diagnostic value of these indexes was further evaluated by ROC curve analysis. Logistic regression model was used to analyze the diagnostic implication of combined assay. The expression levels of SA, EA-IgA, Rta-IgG, and VCA-IgA were highest in nasopharyngeal cancer patients. Those indexes were also increased with advanced TNM stage of cancer. The overall diagnostic efficacy was ranked as: VCA-IgA, Rta-IgA, EA-IgA and SA. The combined diagnosis increased the sensitivity to 98.44% and the negative predictive value to 99.03%, without compromising specificity. SA, EA-IgA, Rta-IgG and VCA-IgA expression levels were elevated in nasopharyngeal patients. The combined diagnosis of those serum indexes may improve the diagnostic efficacy of nasopharyngeal carcinoma.