Prognostic value of serum EBV antibodies in patients with nasopharyngeal carcinoma and undetectable pretreatment EBV DNA

Summary

Epstein-Barr virus (EBV) is closely associated with nasopharyngeal carcinoma (NPC). Serum immunoglobulin A (IgA) antibodies against early antigen (EA-IgA) and viral capsid antigen (VCA-IgA) are the most commonly used to screen for NPC in endemic areas. However, the prognostic value of serum EA-IgA and VCA-IgA in patients with NPC were less clear. We hypothesize that serum EA-IgA and VCA-IgA levels have prognostic impact for survival outcomes in NPC patients with undetectable pretreatment EBV (pEBV) DNA. In this series, 334 patients with non-metastatic NPC and undetectable pEBV DNA were included. Serum EA-IgA and VCA-IgA were determined by enzyme-linked immunosorbent assays (ELISA). After analysis, serum EA-IgA and VCA-IgA loads correlated positively with T, N and overall stage (all P < 0.05). Serum EA-IgA was not associated with survival outcomes in univariable analyses. But patients with serum VCA-IgA >1:120 had significantly inferior 5-year progression-free survival (80.4% vs. 89.6%, P=0.025), distant metastasis-free survival (88.4% vs. 94.8%, P=0.050), and locoregional relapse-free survival (88.4% vs. 95.6%, P=0.023; log-rank test). Multivariable analyses revealed that N stage was the only independent prognostic factor (all P < 0.05), but the VCA-IgA became insignificant. Further analyses revealed that serum VCA-IgA was not an independent prognostic factor in early N (N0-1) or advanced N (N2-3) stage NPC. In summary, though both EA-IgA and VCA-IgA correlate strongly with TNM stage, our analyses do not suggest that these antibodies are prognostic biomarkers in patients with NPC and undetectable pEBV DNA.

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