CircKDM4C significantly represses breast cancer proliferation, metastasis and doxorubicin resistance in vitro and in vivo.26 In non–small‐cell lung cancer, circ_0076305 is elevated in NSCLC, and more significantly up‐regulated in DDP‐resistant tissues and cells, which regulates STAT3 expression via sponging miR‐296‐5p.27 Here, STAT3 is linked to breast carcinoma.