The protease cathepsin B (CTSB) has been identified to highly express in cancer (Mijanovic et al., 2019), and associate with poor prognosis of a variety of cancers, including breast cancer, pancreatic cancer, and lung squamous cell carcinoma, which could be used as an independent predictor of these tumors (Gong et al., 2013; Zhang et al., 2014). This evidence concerns the gene CTSB and breast cancer.