Increased copy number of mitochondrial DNA predicts poor prognosis of esophageal squamous cell carcinoma.

Change in mitochondrial DNA (mtDNA) copy number has been reported in esophageal squamous cell carcinoma (ESCC). However, its prognostic implication in ESCC remains largely unknown. Using reverse transcription-quantitative PCR assay, the mtDNA copy number was assessed in a cohort of patients with ESCC (n=141) and normal esophageal tissues (n=45), and the association between variable mtDNA levels and clinical outcomes of patients with ESCC were studied. Data revealed that ESCC patients exhibited an increased mtDNA content compared to control subjects. Furthermore, increased mtDNA content was associated with a significantly increased risk of cancer-associated mortality. This molecular event was associated with poorer survival in patients with ESCC, and was an independent predictor of patient survival. Data demonstrated that increased mtDNA content is a common genetic event in ESCC and may be a predictive factor of poor prognosis for ESCC patients.