Epstein-Barr virus (EBV) infection and family history are significant risk factors associated with undifferentiated nasopharyngeal carcinoma. The presence of aberrant immunoglobulin A (IgA) antibodies against specific EBV antigens in healthy individuals can be predictive of the disease. Very limited reports explored the EBV IgA antibody presence within families of sporadic cases of nasopharyngeal carcinoma. This study aimed to determine whether EBV IgA was observed more frequently among family members of sporadic cases of nasopharyngeal carcinoma compared to community controls and evaluated the non-viral factors as determinants of antibody level. First-degree relatives of nasopharyngeal carcinoma patients (n = 520) and case-matched community controls (n = 86) were recruited. Sera from all individuals were tested in standardized peptide-based EBV IgA ELISA. Data on demographic variables and other exogenous factors were collected using a questionnaire through face-to-face interviews. A similar frequency of EBV IgA (cut-off value/CoV 0.354) was observed in the first-degree relatives of cases and in community controls (41.2% vs. 39.5%, P = 0.770). However, with a higher antibody level (OD(450) = 1.000; about three times standard CoV), the relatives showed significantly higher frequency (36.9% vs. 14.7%, P = 0.011). When adjusted for all exogenous factors, the strongest factors associated with seropositivity are being a father (odds ratio/OR = 4.36; 95% confidence interval/CI = 1.56-12.21) or a sibling (OR = 1.89; 95% CI = 1.06-3.38) of a case of nasopharyngeal carcinoma. The higher level of EBV IgA seroreactivity in first-degree relatives of sporadic cases of nasopharyngeal carcinoma compared to the general population supports the use of EBV IgA ELISA for screening among family members.
Copyright © 2012 Wiley Periodicals, Inc.