The probable mechanism involved effective suppression of glucose‐starvation‐ and chemotherapeutic‐induced cytoprotective autophagy in breast cancer cell lines estrogen‐receptor‐positive MCF7 and triple‐negative MDA‐MB‐231 cells likely through downregulation of mTOR/ULK1 signaling after phloretin treatment. This evidence concerns the gene ESR1 and breast cancer.