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The cytochrome P450 2E1 (CYP2E1) polymorphisms have been implicated in susceptibility to nasopharyngeal carcinoma (NPC). However, the results are inconsistent. The aim of this meta-analysis is to evaluate the association between the CYP2E1 polymorphisms and NPC risk. All eligible case-control studies published up to April 4, 2016 were identified by searching PubMed, Web of Science, CNKI, Wanfang and Weipu databases. The NPC risk associated with the CYP2E1 polymorphism was estimated for each study by odds ratios (OR) together with its 95 % confidence interval (CI), respectively. Seven case-control studies were included. Of those, there were seven studies (1302 cases and 1319 controls) for RsaI/PstI polymorphism and three studies (732 cases and 642 controls) for DraI polymorphism. Overall, a significant association was found for RsaI/PstI polymorphism under recessive and homozygote comparison models (OR = 2.72, 95 % CI 1.73-4.25; OR = 2.64, 95 % CI 1.68-4.16, respectively), while there was no significant association for RsaI/PstI polymorphism under other two genetic models. When stratified by ethnicity, similar results were observed between them. As for DraI polymorphism, we also observed a significant association under recessive and homozygote comparison models, but not for the other two models. This meta-analysis suggests that the CYP2E1 polymorphisms contributed to the susceptibility of NPC, especially in Asian populations.

The human leukocyte antigens (HLA) DRB1 polymorphism has been implicated in susceptibility to nasopharyngeal carcinoma (NPC). However, the results are inconsistent. The aim of this meta-analysis is to evaluate the association between the HLA-DRB1 polymorphisms and NPC risk. All eligible case-control studies published up to June 17, 2015 were identified by searching PubMed, Web of Science, CNKI, Wanfang, and Weipu databases. The NPC risk associated with the HLA-DRB1 polymorphism was estimated for each study by odds ratios (OR) together with its 95 % confidence interval (CI), respectively. Twelve studies with 1152 cases and 1600 controls were included. Overall, a significant positively association between the HLA-DRB1*03, *08, *09, and *10 alleles polymorphism and NPC risk were found (OR = 1.55, 95 % CI 1.30-1.86; OR = 1.44, 95 % CI 1.08-1.92; OR = 1.33, 95 % CI 1.06-1.67; OR = 1.82, 95 % CI 1.02-3.26, respectively), and the HLA-DRB1*01, *11, and *12 alleles were negatively associated with NPC risk (OR = 0.55, 95 % CI 0.39-0.78; OR = 0.62, 95 % CI 0.42-0.91; OR = 0.62, 95 % CI 0.47-0.81, respectively), but we failed to detect any association between other alleles and NPC risk. When stratified by ethnicity, similar results were observed among Asians for HLA-DRB1*03, *08, *09, *11, and *12 alleles and Tunisians for HLA-DRB1*01, *03, and *11 alleles; However, no significant association among Caucasians was observed. This meta-analysis suggests that the HLA-DRB1*03, *08, *09, and *10 alleles polymorphism contributed to the susceptibility of NPC, whereas HLA-DRB1*11 and *12 alleles polymorphism may be an important protective factor for NPC, especially of Asian populations.