Background: In contrast to the recognized role of Helicobacter pylori in the etiology of non-cardia gastric cancer (GC), there is still insufficient epidemiological evidence for the involvement of Epstein-Barr virus (EBV) in gastric carcinogenesis. We aimed to evaluate the relation of antibody profile and antibody reactivity intensity against four individual EBV proteins to GC risk. Methods: We used information from 281 GC cases and 2071 age and sex frequency matched controls recruited in the frame of the MCC-Spain multicase-control study, between 2008 and 2013. Sociodemographic, lifestyle and environmental factors were assessed in face-to-face interviews. Antibody responses to four EBV proteins (EBNA-1, ZEBRA, EA-D, and VCA-p18) were analyzed by multiplex serology. Odds ratios (OR) and 95% confidence intervals were calculated by using logistic regression mixed models to evaluate the association of seropositivity and antibody reactivity against EBV proteins with GC, adjusting for GC risk factors. Stratified analyses by tumor location (cardia vs. non-cardia) and morphology (intestinal vs. diffuse) were done. Results: Among controls, seropositivity for EA-D, ZEBRA, EBNA-1 and VCA-p18 was 85%, 91%, 97% and 99%, respectively. Even though seropositivity for none of the studied proteins was associated with a higher GC risk, increasing antibody reactivity against EBNA-1 and VCA-p18 was associated with higher OR of GC. This association was present for cardia and non-cardia cancer cases, and for intestinal and diffuse types. Conclusion: Our results support the hypothesis that EBV may play a role in GC etiology, and highlight the importance of evaluating specific antibodies and the dose-response relations when studying widespread infections.

Background: Serological examination of Epstein-Barr virus (EBV) antibodies has been performed for screening nasopharyngeal carcinoma (NPC) and other EBV-associated diseases. Methods: By using xMAP technology, we examined immunoglobulin (Ig) A antibodies against Epstein-Barr virus ( EBV) VCA-gp125, p18 and IgA/IgG against EA-D, EBNA1 and gp78 in populations with distinct diseases, or with different genetic or geographic background. Sera from Cantonese NPC patients (n = 547) and healthy controls (n = 542), 90 members of high-risk NPC families and 52 non-endemic healthy individuals were tested. Thirty-five of NPC patients were recruited to observe the kinetics of EBV antibody levels during and after treatment. Patients with other EBV-associated diseases were collected, including 16 with infectious mononucleosis, 28 with nasal NK/T cell lymphoma and 14 with Hodgkin's disease. Results: Both the sensitivity and specificity of each marker for NPC diagnosis ranged 61-84%, but if combined, they could reach to 84.5% and 92.4%, respectively. Almost half of NPC patients displayed decreased EBV immunoactivities shortly after therapy and tumor recurrence was accompanied with high EBV antibody reactivates. Neither the unaffected members from high-risk NPC families nor non-endemic healthy population showed statistically different EBV antibody levels compared with endemic controls. Moreover, elevated levels of specific antibodies were observed in other EBV-associated diseases, but all were lower than those in NPC. Conclusion: Combined EBV serological biomarkers could improve the diagnostic values for NPC. Diverse EBV serological spectrums presented in populations with different EBV-associated diseases, but NPC patients have the highest EBV activity.