tsRNAs(tRNA-derived small RNAs)—also known as TRFs (tRNA-derived fragments), tiRNAs (tRNA-derived stress-induced RNAs), tRNA halves, etc.—are a recently identified class of small noncoding RNAs that are generated from mature tRNA or tRNA precursors through cleavage by enzymes such as angiogenin, Dicer, RNase Z, and RNase P. Several studies have confirmed that dysregulation of tsRNAs is closely related to the tumorigenesis of breast cancer, nasopharyngeal cancer, lung cancer, and so on. Here, DICER1 is linked to breast cancer.