EREG and breast cancer: To explore whether lnc021545, miR-330-3p, and EREG work together to regulate the malignancy of BC, a cooperative ratio introduced by us as the sum of the relative expressions of lnc021545 and EREG divided by the relative expression of miR-330-3p was applied to address the cooperative prediction utilization of the three molecules with certain clinicopathologic features of BC.