Epstein-Barr viral serology in nasopharyngeal carcinoma patients in the USSR and Cuba, and its value for differential diagnosis of the disease.

Serological responses to Epstein-Barr virus (EBV)-associated antigens were studied in nasopharyngeal carcinoma (NPC) patients in 2 countries non-endemic for the disease: the USSR (77 cases) and Cuba (55 cases). Two age- and sex-matched control groups were available, one consisting of patients with other head-and-neck tumours (OHNT) (171 from the USSR and 56 from Cuba), and the other of normal individuals (blood donors) (83 from the USSR and 80 from Cuba). Unlike the control groups, NPC patients from both countries had high levels of IgG and IgA antibodies, similar to those seen in patients from endemic areas. The only difference between NPC patients in the USSR and those in Cuba was lower (2-2.5 fold) anti-VCA IgG and IgA antibody titres. Using one-factor and multi-factor statistical methods the diagnostic value of different titres of EBV-specific IgG and IgA antibodies and their combinations for NPC patients (in the USSR) was evaluated. It was found that with simple mathematical analysis of EBV-specific antibody titres a differential diagnosis of NPC could be made to a significance level of 90%. The data obtained demonstrated the importance and reliability of EBV serology in the diagnosis of NPC in areas of low incidence of the disease.