We analyzed 190 patients with BC before and after NACT for DTCs in the BM and further characterized CTCs by molecular profiling, including HER2, the hormonal receptors ER and PR, and stem cell–like CTCs (slCTCs) [aldehyde dehydrogenase 1 (ALDH1) and/or EMT-like]. This evidence concerns the gene ALDH1A1 and breast cancer.