Epstein-Barr virus DNA quantification and follow-up in Tunisian nasopharyngeal carcinoma patients.

The prognostic value of the Epstein-Barr virus (EBV) DNA load in sera of nasopharyngeal carcinoma (NPC) patients measured before any treatment, after treatment and before relapse was assessed. The real-time polymerase chain reaction was used to detect the viral load levels among 74 NPC subjects. Patients were followed up for a period going from 1 to 6 years (median 4 years). Before treatment, the EBV DNA load was correlated with lymph node involvement and advanced stages. After treatment, the viral load level declined significantly and patients presenting a viral load level lower than 1000 copies/ml showed a better overall survival (OS). Moreover, a significant result was found when the 6-year OS rates of patients having fewer or more than 15,000 copies/ml of viral load before relapse were compared. These results suggest that the EBV DNA load quantification after treatment may be a useful predictor of disease progression and survival.

Lack of association between human leukocyte antigen-E alleles and nasopharyngeal carcinoma in Tunisians.

Nasopharyngeal carcinoma (NPC), a cancer with a remarkable geographical and worldwide ethnic distribution, has been strongly associated with human leukocyte antigen (HLA) class I genes. The presence of additional HLA risk factors has been suggested by several reports. In the present study, we analyzed the implication of HLA-E gene polymorphisms in NPC susceptibility in Tunisians, a population characterized by an intermediate incidence of NPC with specific clinical features. Peripheral blood DNA was obtained from 185 patients with NPC and 177 matched controls. Genotyping for three single-nucleotide polymorphisms, codon 83Gly/Arg, codon 157Arg/Gly, and codon 107Arg/Gly, was performed using the polymerase chain reaction method. The HLA-E*01:01 and HLA-E*01:03 were the only alleles found among Tunisians. The HLA-E*01:03 allele had a slight increase in patients with NPC (43%) compared with controls (37%), but the difference did not reach a statistical significance. Our results show the lack of association between HLA-E alleles and NPC in the Tunisian population. This is not in agreement with the previous studies, suggesting a potential implication of HLA-E gene polymorphisms in the susceptibility to NPC among populations with high-risk incidence. Our study further supports the dissimilarity of NPC between populations with different NPC incidence.

Association of HLA-G polymorphisms with nasopharyngeal carcinoma risk and clinical outcome.

The expression of human leukocyte antigen-G (HLA-G) in tumor cells may facilitate the escape of the tumor from immunosurveillance; thus the aim of this study was to evaluate the influence of HLA-G polymorphisms occurrence on nasopharyngeal carcinoma (NPC) susceptibility, severity, and survival. Using the restriction fragment length polymorphism-polymerase chain reaction and the amplification refractory mutation system-polymerase chain reaction method, 186 Tunisian patients and 189 healthy controls were genotyped for nonsynonymous polymorphisms in HLA-G codon 31Thr/Ser, codon 110Leu/Ile and codon 130Leu/framshift. When allele, genotype and haplotype frequencies between patients and controls were compared for each single nucleotide polymorphisms (SNP), no statistical significant differences were observed. According to the lymph node status and the tumor stages, the Ile110 allele was shown to be significantly less frequent among patients with a positive lymph node status and more severe tumor stages (stage I-II vs III-IV), respectively. Moreover, the codon 130C deletion occurrence was significantly associated with a decreased NPC free disease and overall survival. Altogether our results suggest a possible role for HLA-G locus in NPC progression and aggressiveness.