Targeted therapy for breast cancer remains big challenges due to high costs and risk of overtreatment.16 Recent studies have highlighted promising potential of circRNAs as important modulators in human cancers.17, 18 Our study conducted hsa_circRNA_002178 loss‐of‐function experiments and finally identified that hsa_circRNA_002178 functioned as a miR‐328‐3p sponge and impaired miR‐328‐3p‐targeted repression of COL1A1. Here, COL1A1 is linked to cancer.