Abstract
BackgroundEpstein-Barr virus (EBV) is considered to be closely associated with nasopharyngeal carcinoma (NPC), in which EBV-encoded latent membrane protein 1 (LMP1) was found to have an oncogenic role. However, the results published on the LMP1 polymorphism are inconsistent. In the present study, we performed a meta-analysis to determine the frequency of the associations and a more precise association between NPC and EBV LMP1 gene variants (30-bp deletion (del)/XhoI-loss).MethodsEligible articles met the inclusion/exclusion criteria and were identified in the following electronic databases: PubMed, ScienceDirect, and SciELO. Consequently, the data of interest were extracted and plotted in a table to calculate the frequency and odds ratio (OR) of the outcomes of interest (30-bp del-LMP1/XhoI-loss) in patients with NPC. Study quality (Newcastle-Ottawa Scale (NOS)), publication bias, and heterogeneity were assessed.ResultsThirty-one observational studies were included with a total of 2,846 individuals (NPC, n = 1,855; control, n = 991). The risk of bias in relation to study quality evaluated by NOS was considered low. The pooled estimate of the frequency of 30-bp del-LMP1 and XhoI-loss in patients with NPC was 77% (95% confidence interval (CI): 72 to 82) and 82% (95% CI: 71 to 92), respectively. There was an association between 30-bp del-LMP1 and NPC susceptibility (OR = 2.86, 95% CI: 1.35 to 6.07, P = 0.00). Similarly, there was an association between XhoI-loss and NPC (OR = 8.5, 95% CI: 1.7 to 41, P = 0.00). However, when we analyze the co-existence of the 30-bp del-LMP1 and XhoI-loss in patients with NPC, there was no association (OR = 1.09, 95% CI: 0.06 to 18.79, P = 0.002).ConclusionsOur results suggest an association between the 30-bp del-LMP1 and XhoI-loss with NPC susceptibility. However, our data should be interpreted with caution because the sample size was small, and there was heterogeneity between the studies. Thus, future studies are needed with adjusted estimates to simultaneously evaluate multiple factors involved in the development of NPC.Systematic review registrationPROSPERO CRD42014013496.Electronic supplementary materialThe online version of this article (doi:10.1186/s13643-015-0037-z) contains supplementary material, which is available to authorized users.
Highlights
Epstein-Barr virus (EBV) is considered to be closely associated with nasopharyngeal carcinoma (NPC), in which EBV-encoded latent membrane protein 1 (LMP1) was found to have an oncogenic role
Nasopharyngeal carcinoma (NPC) is an aggressive tumor associated with Epstein-Barr virus (EBV) that initially affects the layer of epithelial cells in the nasopharynx and preferably arises in the Rosenmüller’s fossa [1,2]
The worldwide incidence of NPC is considered rare, and affected individuals for many years had a poor prognosis that reflected in a reduced survival rate, but the survival of NPC patients is relatively high under the current treatment protocol and the introduction of intensity-modulated radiotherapy (IMRT) [6]
Summary
Epstein-Barr virus (EBV) is considered to be closely associated with nasopharyngeal carcinoma (NPC), in which EBV-encoded latent membrane protein 1 (LMP1) was found to have an oncogenic role. NPC is defined as a peculiar type of head and neck cancer due to its clinical status, etiology, pathology, epidemiology, and manner of response to treatment [3,4]. In view of these factors, EBV and NPC have very distinct epidemiological and clinical patterns, given that EBV is ubiquitous and causes a latent infection in 95% of the world population, with the majority of these infections being benign [5].
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