Single nucleotide polymorphisms in the mitochondrial displacement loop and outcome of esophageal squamous cell carcinoma

The D-loop region of mtDNA was sequenced for 60 ESCC patients recorded in the Fourth Hospital of Hebei Medical University between 2003 and 2004. The 5 year survival curve were calculated with the Kaplan-Meier method and compared by the log-rank test at each SNP site, a multivariate survival analysis was also performed with the Cox proportional hazards method.The SNP sites of nucleotides 16274G/A, 16278C/T and 16399A/G were identified for prediction of post-operational survival by the log-rank test. In an overall multivariate analysis, the 16278 and 16399 alleles were identified as independent predictors of ESCC outcome. The length of survival of patients with the minor allele 16278T genotype was significantly shorter than that of patients with 16278C at the 16278 site (relative risk, 3.001; 95% CI, 1.029 - 8.756; p = 0.044). The length of survival of patients with the minor allele 16399G genotype was significantly shorter than that of patients with the more frequent allele 16399A at the 16399 site in ESCC patients (relative risk, 3.483; 95% CI, 1.068 - 11.359; p = 0.039).Genetic polymorphisms in the D-loop are independent prognostic markers for patients with ESCC. Accordingly, the analysis of genetic polymorphisms in the mitochondrial D-loop can help identify patient subgroups at high risk of a poor disease outcome.Esophageal cancer is one of the commonest cancers in the population of northern central China with an age-standardized annual incidence rate > 125/100,000 [1]. Cumulative mortality attributed to esophageal cancer is approximately 20% for women and 25% for men [2]. The prognosis of esophageal cancer remains poor, despite improved diagnosis and therapeutic strategies, mostly because of its aggressive nature. The performance status, the TNM stage, and lymph node metastases seem to be the predictive factors of esophageal cancer; some molecular factors, such as p53 mutaion and NF-kappaB expression level, also show predictive power for esophageal cancer outcome