We calculated the frequency of eccDNA generation from 24 chromosomes (percentage of EPM per chromosome) and observed the eccDNA-frequency variation in each chromosome of GCT sample was higher than that of NAT (Fig. 1I), especially in chr 8, 9, 20 and 21 (Multiple paired t test, q value < 0.05), reflecting the increased genomic instability of cancer cells in GC. This evidence concerns the gene BRD2 and cancer.