CTSD and neoplasm: Differential gene analysis showed that the HMGA1 high-tumor stem cell subgroup specifically expresses characteristic genes such as TMSB10 (encoding thymosin β10, closely related to the occurrence and development of various solid tumors [14]), CTSD (encoding cathepsin D, a star marker for poor prognosis in BC [15]), and LGALS1 (encoding soluble galectin-1, promoting the formation of inhibitory tumor immune microenvironment [16]), suggesting it may be a risk factor for poor prognosis in BC.