Focal copy-number increases (genomic amplification) pinpoint oncogenic driver genes and therapeutic targets in cancer genomes. With the advent of genomic technologies, recurrent genomic amplification has been mapped throughout the genome. Recurrent amplification could be solely due to positive selection for the tumor-promoting effects of amplified gene products. Alternatively, recurrence could result from the susceptibility of the loci to amplification. Distinguishing between these possibilities requires a full understanding of the amplification mechanisms. Two mechanisms, the formation of double minute (DM) chromosomes and breakage–fusion–bridge (BFB) cycles, have been repeatedly linked to genomic amplification, and the impact of both mechanisms has been confirmed in cancer genomics data. We review the details of these mechanisms and discuss the mechanisms underlying recurrence.

焦点拷贝数增加（基因组扩增）可查明癌症基因组中的致癌驱动基因和治疗靶标。随着基因组技术的出现，循环基因组扩增已被定位在整个基因组中。重复扩增可能完全是由于对扩增的基因产物的促肿瘤作用的阳性选择。或者，可以由基因座对扩增的敏感性导致复发。区分这些可能性需要对扩增机制有充分的了解。双重机制（DM）染色体的形成和断裂-融合-桥（BFB）循环这两种机制已与基因组扩增反复关联，并且这两种机制的影响已在癌症基因组学数据中得到证实。