It is ubiquitously distributed in various tumors, including BC, nonsmall-cell lung cancer, laryngeal cancer, ovarian cancer, and gastric cancer.[4–8] Many studies showed that ALDH1 is a marker of BCSCs,[3,5,9,10] while Kunju et al[11] reported that ALDH1-positive benign breast epithelial cells may predict an increased risk for the development of BC. Here, ALDH1A1 is linked to lung cancer.