Association of mitochondrial DNA copy number in peripheral blood leukocytes with risk of esophageal adenocarcinoma

Alterations of mitochondrial DNA (mtDNA) have been associated with the risk of a number of human cancers; however, the relationship between mtDNA copy number in peripheral blood leukocytes and the risk of esophageal adenocarcinoma (EAC) has not been reported. In this study, we determined relative mtDNA copy number in peripheral blood leukocytes of 218 EAC cases and 218 frequency-matched controls. We calculated odds ratios and 95% confidence intervals using unconditional logistic regression, adjusting for age, sex and smoking status. MtDNA copy number was significantly lower in cases than in controls (mean SD, 1.16 0.30 versus 1.27 0.43, P 0.002). Dichotomized at the median value of mtDNA copy number in the controls, low mtDNA copy number was significantly associated with an increased risk of EAC (odds ratio: 1.55, 95% confidence interval: 1.052.29). A significant doseresponse relationship was observed between mtDNA copy number and risk of EAC in quartile analysis. Our results suggest that low mtDNA copy number in peripheral blood leukocytes is associated with increased susceptibility to EAC.