Studies have indicated that the development of lung metastasis in breast cancer may be associated with epithelial‐mesenchymal transition (EMT), breast cancer stem cells, the tumor microenvironment, and aberrant activation of signaling pathways in tumor cells.[5] The transforming growth factor‐β(TGF‐β)signaling pathway has been closely linked to the progression of breast cancer.[6] During the early stages, TGF‐β impedes cell cycle progression and stimulates cancer cell apoptosis, thereby exerting tumor‐suppressive effects. This evidence concerns the gene TGFB1 and breast cancer.