Fig. 1

mtDNA copy number in clinical samples from ESCC patients. A Patients were divided into two groups: a group with an mtDNA copy number ≥ the median (n = 45) and a group with an mtDNA copy number < the median (n = 43). B Overall survival between the mtDNA copy number < median and mtDNA copy number ≥ median groups was not significantly different. However, the mtDNA copy number < median group was significantly associated with shortened recurrence-free survival (p = 0.027)