The Epstein-Barr virus (EBV) plays a key role in the development of undifferentiated nasopharyngeal carcinoma (uNPC). In uNPC endemic regions EBV-specific antibodies and plasma EBV DNA load are used as markers for the early detection of uNPC and monitoring of the disease. In non-endemic regions, such studies were practically not conducted. The aim of this study was to compare the clinical significance of EBV serological markers and plasma EBV DNA levels for uNPC patients in a non-endemic region, Russia. The results obtained indicate that both viral capsid antigen/immunoglobulin A (VCA/IgA) antibodies and plasma EBV DNA copies can effectively be used for nasopharyngeal carcinoma (NPC) diagnosis. Besides, plasma EBV DNA load was found to be a more sensitive marker of uNPC than VCA/IgA antibody titres, as it reflected the effect of the therapy in stages of remission and relapse of the disease more precisely. Our study, for the first time, demonstrates that the simultaneous use of plasma EBV DNA loads and VCA/IgA antibody levels are indispensable markers for uNPC in non-endemic regions: a serological marker can be more effectively used for NPC screening, but EBV DNA copies are better for monitoring the disease. However, both markers turned out to be practically unsuitable for assessing the clinical status of patients. Serological markers did not correlate with any signs of the tumour process estimated by tumour, node and metastasis (TNM) classification and the plasma EBV DNA loads correlated only with the size of the pathologically altered lymph nodes (N). Additional study is required to confirm these findings.

The goal of this work was to describe a method for diagnosis of the non-keratinizing nasopharyngeal carcinoma (nNPC) in cases of the undetectable primary tumor location. The method is based on evaluation of IgG and IgA antibody levels to the capsid (VCA) and early antigens (EA) of the Epstein-Barr virus (EBV). The diagnosis of nNPC is established by a so-called decision rule. The latter was created by mathematical processing of the method of multifactor analysis of the results of anti-EBV antibody testing of 72 patients with clinically and morphologically confirmed nNPC and 72 patients with other head and neck benign tumors (OHNT) not associated with EBV, which were tested as a control group. The diagnostic value of the decision rule which was tested in the group of 77 patients with confirmed nNPC and 231 patients of a control group was high. The numbers of false negative and false positive cases were equal to 5.2% (4/77) and 6.5% (17/231), respectively. Among 32 patients with undetectable primary tumors the decision rule was able to identify 11 cases of nNPC. This diagnosis later was confirmed by morphological and instrumental methods of study. Only in two cases, false negative result was obtained (2/32; 6.3%) indicating that the serological diagnostics of nNPC with the decision rule is highly specific but not exact. Thus, the data obtained allowed us to conclude that the serological testing of EBV specific antibody evaluated by the decision rule can be recommended as an important test supplementing the standard methods of pdNPC diagnostics including cases with undetected primary tumor location.

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The article presents a draft of clinical recommendations for the diagnosis and treatment of differentiated thyroid cancer in adult patients, which provides a modern examination algorithm, discusses the basic principles of laboratory, instrumental diagnostics and treatment approaches.